Dissertations / Theses: 'Polyethylene nanocomposites'

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Green, Christopher Duncan. "Polyethylene-montmorillonite nanocomposites." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/65001/.

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Nanocomposite materials are currently attracting much interest due to their possibility of global property improvement – mechanical strength, toughness, electrical breakdown strength, electrical erosion resistance and flame retardancy. In order to disperse montmorillonite clay (MMT) into polyethylene (PE), the clay sheets need to be rendered organophilic. Masterbatches with a high level (~40 %wt) of organomodified clay can then be dispersed into a host by a simple mechanical process. Two chemically different masterbatches were purchased: Nanoblend 2101 from PolyOne Corp. and C30PE from Nanocor Inc. These were let down using a RandcastleTM single screw extruder with a patented mixing device to provide elongational flow. Wide angle X-ray diffraction was used together with transmission electron microscopy to evaluate the particle dispersion, which consisted of intercalated clay organised in clusters up to one micron in diameter. The performance of these materials was assessed in terms of AC ramp breakdown statistics, dielectric spectroscopy, dynamic and tensile mechanical properties. Nanoblend masterbatch consistently improved the breakdown statistics, more than overcoming the inherent demerit of extrusion, which mildly aged the unfilled material (as confirmed by Raman spectroscopy.) On the other hand, even low loading levels of Nanocor could result in reduced breakdown strength and increased scatter. Furthermore, both sets of materials demonstrated large dielectric losses at power frequencies and poorer performance under mechanical tension. These materials would therefore require considerable development before they could confidently be used commercially. The nature of the PE-MMT interactions was examined by investigating the crystallisation kinetics and resulting morphologies with differential scanning calorimetry and scanning electron microscopy. By varying the masterbatch type, loading level and crystallisation temperature, it was possible to study a wide range of supercrystalline morphologies using a permanganic etching technique. This is a useful contribution to the field of nanocomposites research. It is known that the morphologies of polymers can affect their mechanical properties and electrical treeing behaviour, and so it is possible that controlled crystallisation could provide a route toward designer materials with optimised behaviour.

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Isik, Fatma. "Nanocomposites Based On Blends Of Polyethylene." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12606338/index.pdf.

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In this study the effects of compatibilizer type, organoclay type, and the addition order of components on the morphological, thermal, mechanical and flow properties of ternary nanocomposites based on low density polyethylene, LDPE were investigated. As compatibilizer, ethylene/methyl acrylate/glycidyl methacrylate, ethylene/glycidyl methacrylate, and ethylene/butyl acrylate/maleic anhydride
as organoclay Cloisite&
#61666
15A, Cloisite&
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25A and Cloisite&
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30B were used. All samples were prepared by a co-rotating twin screw extruder, followed by injection molding. Before producing the ternary nanocomposites, in order to determine the optimum amount of the organoclay and compatibilizer, binary mixtures of LDPE/organoclay and LDPE/compatibilizer blends with different compositions were prepared. Based on the results of the mechanical tests, compatibilizer and organoclay contents were determined as 5 wt. % and 2 wt % respectively. After that, ternary nanocomposites were prepared with each compatibilizer/organoclay system and characterization of these nanocomposites was performed. Among the investigated addition orders, mechanical test results showed that the best sequence of component addition was (PCoC), in which LDPE, compatibilizer and organoclay were simultaneously compounded in the first run of the extrusion. Considering the ternary nanocomposites, compositions of LDPE/E-MA-GMA/15A, LDPE/E-GMA/15A and LDPE/E-nBA-MAH/30B showed the highest improvement in mechanical properties. According to the DSC analysis, addition of organoclay and compatibilizer does not influence the melting behavior of the compositions and both compatibilizers and organoclay types have no nucleation activity in LDPE. In the X-Ray analysis, the highest increase of the basal spacing for ternary nanocomposites obtained for LDPE/E-BA-MAH/organoclay nanocomposites. This increase was 83 %, 198 %, and 206 % for samples containing 15A, 25A and 30B respectively.

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Shaito, Ali Al-Abed. "Long Term Property Prediction of Polyethylene Nanocomposites." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9738/.

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The amorphous fraction of semicrystalline polymers has long been thought to be a significant contributor to creep deformation. In polyethylene (PE) nanocomposites, the semicrystalline nature of the maleated PE compatibilizer leads to a limited ability to separate the role of the PE in the nanocomposite properties. This dissertation investigates blown films of linear low-density polyethylene (LLDPE) and its nanocomposites with montmorillonite-layered silicate (MLS). Addition of an amorphous ethylene propylene copolymer grafted maleic anhydride (amEP) was utilized to enhance the interaction between the PE and the MLS. The amorphous nature of the compatibilizer was used to differentiate the effect of the different components of the nanocomposites; namely the matrix, the filler, and the compatibilizer on the overall properties. Tensile test results of the nanocomposites indicate that the addition of amEP and MLS separately and together produces a synergistic effect on the mechanical properties of the neat PE Thermal transitions were analyzed using differential scanning calorimetry (DSC) to determine if the observed improvement in mechanical properties is related to changes in crystallinity. The effect of dispersion of the MLS in the matrix was investigated by using a combination of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Mechanical measurements were correlated to the dispersion of the layered silicate particles in the matrix. The nonlinear time dependent creep of the material was analyzed by examining creep and recovery of the films with a Burger model and the Kohlrausch-Williams-Watts (KWW) relation. The effect of stress on the nonlinear behavior of the nanocomposites was investigated by analyzing creep-recovery at different stress levels. Stress-related creep constants and shift factors were determined for the material by using the Schapery nonlinear viscoelastic equation at room temperature. The effect of temperature on the tensile and creep properties of the nanocomposites was analyzed by examining tensile and creep-recovery behavior of the films at temperatures in the range of 25 to -100 oC. Within the measured temperature range, the materials showed a nonlinear temperature dependent response. The time-temperature superposition principle was successfully used to predict the long term behavior of LLDPE nanocomposites.

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Alghamdi, Abdulaziz. "Mechanical characterisation of novel polyethylene-based nanocomposites." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14120/.

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Polymer-based nanocomposites are of significant current research interest owing to their outstanding mechanical properties, light weight, processability and low cost. They are also increasingly being considered for a range of industrial applications, including packaging, fuel tanks, gas barriers and high performance films. Ultra-high molecular weight polyethylene (UHMWPE) is already used in various applications, such as lightweight body armour because of its high impact resistance with light weight and total joint replacement due to its high wear resistance. However, a broader use of UHMWPE is limited by the complexity and cost of the manufacturing process, which can be attributed to its high viscosity at processing temperatures. The processability of UHMWPE can be improved by blending with a compatible, lower molecular weight polymer, however, this inevitably results in a reduction in some of the useful properties, such as impact resistance. In this work the potential of adding nano-fillers to such blends to create a range of nanocomposite polymers with the advantages of easy processability and enhanced properties is investigated. The overall aim of this research was to investigate the effect of processing method, strain rate, nanoparticle type and content on the morphological, thermal and mechanical properties of a family of novel polyethylene-based nanocomposites. Polymer nanocomposites of blended UHMWPE and high density polyethylene (HDPE) reinforced with carbon black (CB), carbon nanotubes (CNTs) or inorganic clay were prepared using conventional processing techniques. After initial experiments into the effects of processing parameters, two sets of processing parameters were selected that gave different blend morphology in order to investigate the effect of this on the blend properties and nanofiller dispersion. Characterization of the pure, blended and nanocomposite materials was achieved by the application of combination of experimental techniques. Tensile testing was carried out to characterise the effect of processing method, strain rate, ambient temperature, nanoparticle type and content on the stress-strain behaviour and also to study heat generation during plastic deformation at high strain rates. Depth sensing indentation (DSI) tests were carried out to characterise the effect of processing method, ambient temperature, nanoparticle type and content on the near-surface properties of the materials at a micro-scale under a more complex state of stress that more closely approximates that seen in impact applications. The creep behaviour of the materials was investigated at macro and micro scales at various ambient temperatures. This is important as a weakness of UHMWPE is poor creep resistance and it would be extremely useful if blending or the addition of nanofillers could improve this. A phenomenological model was used to analyse the creep data as this can be usefully used to predict creep performance in service and to aid understanding of the creep phenomena in these materials. The results included in this work are summarised below. Firstly, it was seen that processing parameters had a significant effect on the morphology of the blends, which in turn affected the blend properties and the dispersion of nanoparticles in the blend. Secondly, it was seen that heat generation during plastic deformation of the polyethylene blends and nanocomposites was significantly dependent on morphology, strain rate, nanoparticle type and content. Furthermore, this temperature increase strongly affected the material properties at high strain rates, which is an important consideration if these materials are to be used in high strain rate applications, e.g. as replacement for UHMWPE in helmets and body armour. Thirdly, the macro and micro viscoelastic behaviour of the materials was strongly dependent on the morphology, nanoparticle type and content. A significant increase in creep resistance compared with UHMWPE could be engineered by a careful selection of blend and nanoparticle type and weight fraction. It can be seen, therefore, that a new class of cheap and easy processable polymer nanocomposites have been characterised that can give a range of property sets dependent on the blend processing and nanofiller type and weight fraction. Although certain compromises in property sets are unavoidable, e.g. it is difficult to engineer maximum creep and impact resistance in the same material, this ability to tailor properties could potentially increase the range of applications for these materials and enable better product design.

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BAFNA, AYUSH ASHOK. "POLYETHYLENE-CLAY NANOCOMPOSITES: PROCESSING-STRUCTURE-PROPERTY RELATIONSHIP." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1083810121.

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Shaito, Ali Al-Abed D'Souza Nandika Anne. "Long term property prediction of polyethylene nanocomposites." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-9738.

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Bafna, Ayush A. "Polyethylene-clay nanocomposites processing-structure-property relationship /." Cincinnati, Ohio : University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1083810121.

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Chan, Hong Yu. "Crystallization of polypropylene/vermiculite and polyethylene/vermiculite nanocomposites." access abstract and table of contents access full-text, 2004. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21173990a.pdf.

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Thesis (M.Sc.)--City University of Hong Kong, 2004.
At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Aug. 31, 2006) Includes bibliographical references.

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Al-Fouzan, Abdulrahman M. "Polyethylene Terephthalate / clay nanocomposites. Compounding, fabrication and characterisation of the thermal, rheological, barrier and mechanical properties of Polyethylene Terephthalate / clay nanocomposites." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5283.

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Polyethylene Terephthalate (PET) is one of the most important polymers in use today for packaging due to its outstanding properties. The usage of PET has grown at the highest rate compared with other plastic packaging over the last 20 years, and it is anticipated that the increase in global demand will be around 6% in the 2010-2015 period. The rheological behaviour, thermal properties, tensile modulus, permeability properties and degradation phenomena of PET/clay nanocomposites have been investigated in this project. An overall, important finding is that incorporation of nanoclays in PET gives rise to improvements in several key process and product parameters together - processability/ reduced process energy, thermal properties, barrier properties and stiffness. The PET pellets have been compounded with carefully selected nanoclays (Somasif MAE, Somasif MTE and Cloisite 25A) via twin screw extrusion to produce PET/clay nanocomposites at various weight fractions of nanoclay (1, 3, 5, 20 wt.%). The nanoclays vary in the aspect ratio of the platelets, surfactant and/or gallery spacing so different effect are to be expected. The materials were carefully prepared prior to processing in terms of sufficient drying and re-crystallisation of the amorphous pellets as well as the use of dual motor feeders for feeding the materials to the extruder. The rheological properties of PET melts have been found to be enhanced by decreasing the viscosity of the PET i.e. increasing the 'flowability' of the PET melt during the injection or/and extrusion processes. The apparent shear viscosity of PETNCs is show to be significantly lower than un-filled PET at high shear rates. The viscosity exhibits shear thinning behaviour which can be explained by two mechanisms which can occur simultaneously. The first mechanism proposed is that some polymer has entangled and few oriented molecular chain at rest and when applying high shear rates, the level of entanglements is reduced and the molecular chains tend to orient with the flow direction. The other mechanism is that the nanoparticles align with the flow direction at high shear rates. At low shear rate, the magnitudes of the shear viscosity are dependent on the nanoclay concentrations and processing shear rate. Increasing nanoclay concentration leads to increases in shear viscosity. The viscosity was observed to deviate from Newtonian behaviour and exhibited shear thinning at a 3 wt.% concentration. It is possible that the formation of aggregates of clay is responsible for an increase in shear viscosity. Reducing the shear viscosity has positive benefits for downstream manufacturers by reducing power consumption. It was observed that all ii three nanoclays used in this project act as nucleation agents for crystallisation by increasing the crystallisation temperature from the melt and decreasing the crystallisation temperature from the solid and increasing the crystallisation rate, while retaining the melt temperature and glass transition temperatures without significant change. This enhancement in the thermal properties leads to a decrease in the required cycle time for manufacturing processes thus potentially reducing operational costs and increasing production output. It was observed that the nanoclay significantly enhanced the barrier properties of the PET film by up to 50% this potentially allows new PET packaging applications for longer shelf lives or high gas pressures. PET final products require high stiffness whether for carbonated soft drinks or rough handling during distribution. The PET/Somasif nanocomposites exhibit an increase in the tensile modulus of PET nanocomposite films by up to 125% which can be attributed to many reasons including the good dispersion of these clays within the PET matrix as shown by TEM images as well as the good compatibility between the PET chains and the Somasif clays. The tensile test results for the PET/clay nanocomposites micro-moulded samples shows that the injection speed is crucial factor affecting the mechanical properties of polymer injection moulded products.

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Karlsson, Mattias. "Investigation of the dielectric breakdown strength of polymer nanocomposites." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227815.

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The aim of this thesis is to investigate the possibility of enhancing the dielectric breakdown strength (DBS) of low density polyethylene (LDPE) with addition of voltage stabilizing additives. In the first part of the thesis, the influence of various process parameters on the alternating current DBS of pure LDPE and LDPE containing either 3 or 30 wt% magnesium oxide nanoparticles was investigated. It was found that the influence of moisture, crystalline structure and process stabilizing additives did not affect the DBS. In the second part of the thesis the effect of five different voltage stabilizing additives was investigated to enhance the DBS. No significant improvement in DBS could be seen for additives mixed with neat LDPE or LDPE nanocomposites by extrusion (typical DBS values ranged between 109-116 kV/mm for neat LDPE). However, the compounding by extrusion resulted in better stability of the breakdown data. A method to swell voltage stabilizing additives into the polymer matrix with solvents have been developed and evaluated. No significant improvements in breakdown strength could be seen for neat LDPE, but the DBS was increased by 15-20 % at low probability of failure for the LDPE nanocomposites. Further work is required to investigate if this increase is significant. It is believed that it is critical to dissolve a higher amount of the voltage stabilizing additives into the polymer matrix. The actual concentrations of the additives need to be quantified with chromatographic methods or infrared spectroscopy.

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Capaldi, Franco Mario 1977. "Atomistic simulations of octacyclopentyl polyhedral oligomeric silsesquioxane polyethylene nanocomposites." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32388.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.
"June 2005."
Includes bibliographical references.
As the scientific community develops the ability to create composites which incorporate nanoscopic filler particles, the detailed atomic arrangement and atomic interactions become significant in determining the composite properties. Nanoscopic fillers such as carbon nanotubes, polyhedral oligomeric silsesquioxane (POSS), and layered silicates have already been successfully used to improve the thermal and mechanical properties of polymers. On this length scale, details describing particle organization, interaction between particles, and interactions between particle and matrix are needed to understand the behavior of the composite. In this thesis, we use atomistic simulations to investigate the detailed behavior of a blended octacyclopentyl polyhedral oligomeric silsesquioxane (CpPOSS) / polyethylene (PE) nanocomposite. The model potential employed to describe the atomic interactions in these systems is capable of reproducing the experimental vibrational and crystal structures for the POSS well. The mechanical properties of an infinite crystal were calculated. The), are anisotropic with a Reuss average isotropic elastic modulus of 11.78 GPa. Simulations of CpPOSS/PE composites revealed that the POSS had a stiffening effect on the polymer. Simulations revealed that both PE and POSS dynamics as measured by translational and rotational diffusivities decreased, the glass transition temperature increased, and both the density and modulus increased with increasing POSS content. Micromechanical models were fit to the composite modulus which allowed effective mechanical particle sizes to be determined.
(cont.) The POSS was found to aggregate into small necklace structures which have internal ordering similar to the crystal phase. The formation of crystallites was found to be energetically favorable in this system. A coarse grained potential which accounts for both the attraction and orientation between particles was developed to aid the further study of aggregation and crystallization in these composites. The interface between the POSS and the polymer is found to consist of polymer chains aligned tangentially to the POSS cage. This layer has increased mobility tangential to the surface of the particle and decreased mobility in the radial direction. Though it is very thin, consisting of only 1 or 2 monolayers of polymer, due to the small size of the POSS particle, the weight fraction of polymer in the interfacial region is as high as 43 % in the 25 weight percent CpPOSS/PE composite. These simulations reveal the formation of structure on both the angstrom length scale in the polymer near the interface and the mesoscopic length scale between the POSS particles.
by Franko M. Capaldi.
Ph.D.

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Lau, K. Y. "Structure and electrical properties of silica-based polyethylene nanocomposites." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/358889/.

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The topic of polymer nanocomposites remains an active area of research in the dielectrics community, due to the unique electrical properties that these materials could exhibit. To explain the behaviour of these materials, the importance of clarifying the interfaces between nanoparticles and polymer matrices has been emphasised. However,understanding of the interface in nanocomposites is unsatisfactory and, consequently,many experimental results remain unexplained. This thesis reports on an investigation into a polyethylene nanocomposite system that contains varying amounts of nanosilica that differ with respect to their surface chemistry. The addition of nanosilica, even with different surface chemistries, was found to enhance the nucleation density of polyethylene and perturb the spherulitic development. While less organised lamellar structures would be expected to lead to a lower breakdown strength, this does not appearto be the case for the material systems considered here under alternating current (AC) fields. In addition, nanosilica filled polyethylene was found to absorb significantly more water than unfilled polyethylene, with the consequence that both the permittivity and the loss tangent increase with increasing duration of water immersion. However, appropriate surface treatment of nanosilica reduces the water absorption effect and modifies the dielectric response of the nanocomposites compared with those containing an equivalent amount of untreated nanosilica. Although water absorption may not be a technologically desirable characteristic, the results indicate that water molecules can act as effective dielectric probes of interfacial factors. Meanwhile, the direct current (DC) breakdown strength reduces with the inclusion of increasing amount of nanosilica in the polyethylene, but surface treatment of nanosilica improves the DC breakdown strength with respect to equivalent nanocomposites containing untreated nanosilica. Results from space charge studies reveal increased space charge accumulation in the presence of the untreated nanosilica and, upon surface treatment of the nanosilica, the charge development was suppressed in comparison with nanocomposites containing an equivalent amount of untreated nanosilica. This observation suggests that space charge accumulation and DC failure are related in these systems and it would seem that control of surface chemistry is particularly critical in connection with the use of nanocomposites in DC applications. Finally, the mechanisms underpinning the concept of filler functionalisation in nanocomposites were investigated via the use of different aliphatic chain length silane coupling agents, and the results show that long silane chains enhance the DC breakdown strength of the resulting nanocomposites. The possible further enhancement in DC breakdown strength is also highlighted. Overall, this thesis demonstrates how a nanoparticle’s interface chemistry can affect both the structure and the electrical properties of the resulting nanocomposites, and serves as an important foundation towards the engineering of nanocomposites as the reliable electricalinsulation materials of the future, through the understanding of the interface.

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Oluz, Zehra. "Additives For Photodegradable Polyethylene." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614537/index.pdf.

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Polyethylene (PE) is one of the most popular polymers used in daily life. However, saturated hydrocarbons cannot absorb the energy of light reaching to earth, so degradation process is rather slow which in return cause disposal problems. On the other hand, it was observed that in presence of oxygen and impurities in the polymer matrix, degradation can be rendered to shorter time intervals. This study covers investigation of effect of three different additives in UV induced oxidative degradation of polyethylene. In this work vanadium (III) acetylacetonate, serpentine and Cloisite 30B were used as additives both together and alone to follow photodegradation of polyethylene. Amount of vanadium (III) acetylacetonate was kept constant at 0.2 wt%, while serpentine and Cloisite 30B were used between 1 and 4 wt%. All compositions were prepared by using Brabender Torque Rheometer, and shaped as thin films by compression molding. Samples were irradiated by UV light up to 500 hours. Mechanical and spectroscopic measurements were carried out in certain time intervals to monitor the degradation. It can be concluded that all combinations of three additives showed the fastest degradation behavior compared to pure PE. In the absence of vanadium (III) acetylacetonate the degradation was slowed and fluctuations were observed in the residual percentage strain at break values. There was not a significant change in tensile strength of all samples. Carbonyl index values followed by FTIR were always in increasing manner. Thermal properties were also investigated by DSC Thermograms and they did not change significantly.

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Tang, Youhong. "Microrheological study on polyethylene/thermotropic liquid crystalline polymer/layered silicates nanocomposites /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CENG%202007%20TANG.

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Reading, Martin. "An investigation into the structure and properties of polyethylene oxide nanocomposites." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/171659/.

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Polymer nanocomposites have attracted great interest over many years, because of the enhanced properties exhibited by such systems. However, it is only recently that the electrical characteristics of this class of material have begun to be studied in detail. Whenever fillers are added to a host polymer matrix, dispersion is of critical importance since, while a well dispersed nanophase may be beneficial, poor dispersion can have negative consequences. Hence, for the nanocomposites to be used appropriately and provide the best properties, a method for observing the dispersion within the matrix is useful. Despite this, evaluating the dispersion of nano-additives in the bulk is far from straight forward using conventional solid-state materials characterization techniques. This study set out to consider the influence of nano-additives on the physical, thermal and electrical properties of poly(ethylene oxide) systems. The initial objective is to investigate the extent to which dispersion of nanofillers and effect of host molecular weight can be inferred from rheological analysis. This investigation covers many systems based upon polyethylene oxide (PEO); PEO blends, thermally aged PEO and PEO composites with montmorillonite (MMT), micro/nano silicon dioxide (SD/nSD) and boehmite fillers (BO). The study continued from dispersion and solution characterisation onto thermal and electrical properties. The effects of additives and treatment on the crystallisation kinetics and thermal transitions are considered. Polymers are most well known for their electrically insulating properties, therefore electrical analysis into AC breakdown and dielectric spectroscopy were also performed. The research has shown that rheology is capable of producing well dispersed PEO nanocomposites. Addition of fillers during the rheology phase produced the expected monotonic increase in viscosity apart from boehmite, which formed a very viscous gel after reaching a threshold loading. Large drops in thermal transitions were observed for the composite samples. All fillers caused a large increase in breakdown strength at higher loadings, except boehmite which caused the breakdown strength to decrease,an effect discussed in detail.

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Gill, Yasir Q. "Preparation and characterization of polyethylene based nanocomposites for potential applications in packaging." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/18052.

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The objective of my work was to develop HDPE clay nanocomposites for packaging with superior barrier (gas and water) properties by economical processing technique. This work also represents a comparative study of thermoplastic nanocomposites for packaging based on linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and Nylon12. In this study properties and processing of a series of linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and Nylon 12 nanocomposites based on Na-MMT clay and two different aspect ratio grades of kaolinite clay are discussed.

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Traina, Matteo. "Preparation and properties of micro- and nanocomposites based on high density polyethylene." Doctoral thesis, Università degli studi di Trento, 2008. https://hdl.handle.net/11572/368262.

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The primary objectives of this thesis were to investigate and compare the fracture and creep behaviour of micro- and nanocomposites based on polyethylene (PE) produced by melt mixing. To achieve these objectives, different fillers were considered: micrometric copper particles, nanometric carbon blacks (CBs) and multiwalled carbon nanotubes (MWCNTs). In the first part of this dissertation, the fracture behaviour of PE-CB composites was investigated via the Essential Work of Fracture (EWF) approach by producing composites with different CBs in order to investigate the effect of the filler particle size. Moreover, several processing (i.e., extrusion) parameters were varied to obtain different degrees of filler dispersion. Experimental results reveal that fracture toughness increases significantly when CB particle size is smaller and as the extent of dispersion of the filler in the polymer matrix is better. Fracture toughness depends on the thermo-mechanical degradation of the polymer matrix that occurs during extrusion. In the second part of this project, creep behaviour of PE-based composites was investigated at several temperatures with assistance from the principle of time-temperature superposition. In particular, the effect of filler dimensions was analyzed by comparing viscoelastic results for composites that contain micrometric copper particles (with an average diameter of 15 and 45 Î¼m) and nanometric carbon blacks (with an average diameter of 15 and 30 nm). In general, these fillers substantially increase the creep resistance of PE, and this phenomenon was more prominent at smaller particle size. This effect was detectable in the linear viscoelastic region (i.e. at low stresses or temperatures), and it became more evident in the non-linear viscoelastic region (i.e. at high stresses or temperatures). In particular, creep compliance and creep rate decrease at smaller particle size. It is postulated that filler particles function as physical crosslink junctions which hinder polymer chain motion and reduce creep deformation. When particle size is reduced at constant filler volume fraction, the physical crosslink density increases such that chain mobility decreases significantly under stress. Finally, the creep behaviour of PE-MWCNT composites were investigated via direct dispersion of MWCNT in the polymer matrix and by using a commercial masterbatch of MWCNT. In all cases, the increase in creep resistance is statistically significant in the linear viscoelastic region (i.e. at low stresses or temperatures) when sufficient dispersion of the nanotubes is achieved. Interestingly enough, creep resistance increases in the non-linear viscoelastic region (i.e. at high stresses or temperatures) regardless of the degree of nanotube dispersion in the matrix. This phenomenon is attributed to nanotube orientation induced by high levels of stress.

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Traina, Matteo. "Preparation and properties of micro- and nanocomposites based on high density polyethylene." Doctoral thesis, University of Trento, 2008. http://eprints-phd.biblio.unitn.it/105/1/TRAINA-Matteo_PhD-thesis-2008_200DPI.pdf.

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The primary objectives of this thesis were to investigate and compare the fracture and creep behaviour of micro- and nanocomposites based on polyethylene (PE) produced by melt mixing. To achieve these objectives, different fillers were considered: micrometric copper particles, nanometric carbon blacks (CBs) and multiwalled carbon nanotubes (MWCNTs). In the first part of this dissertation, the fracture behaviour of PE-CB composites was investigated via the Essential Work of Fracture (EWF) approach by producing composites with different CBs in order to investigate the effect of the filler particle size. Moreover, several processing (i.e., extrusion) parameters were varied to obtain different degrees of filler dispersion. Experimental results reveal that fracture toughness increases significantly when CB particle size is smaller and as the extent of dispersion of the filler in the polymer matrix is better. Fracture toughness depends on the thermo-mechanical degradation of the polymer matrix that occurs during extrusion. In the second part of this project, creep behaviour of PE-based composites was investigated at several temperatures with assistance from the principle of time-temperature superposition. In particular, the effect of filler dimensions was analyzed by comparing viscoelastic results for composites that contain micrometric copper particles (with an average diameter of 15 and 45 μm) and nanometric carbon blacks (with an average diameter of 15 and 30 nm). In general, these fillers substantially increase the creep resistance of PE, and this phenomenon was more prominent at smaller particle size. This effect was detectable in the linear viscoelastic region (i.e. at low stresses or temperatures), and it became more evident in the non-linear viscoelastic region (i.e. at high stresses or temperatures). In particular, creep compliance and creep rate decrease at smaller particle size. It is postulated that filler particles function as physical crosslink junctions which hinder polymer chain motion and reduce creep deformation. When particle size is reduced at constant filler volume fraction, the physical crosslink density increases such that chain mobility decreases significantly under stress. Finally, the creep behaviour of PE-MWCNT composites were investigated via direct dispersion of MWCNT in the polymer matrix and by using a commercial masterbatch of MWCNT. In all cases, the increase in creep resistance is statistically significant in the linear viscoelastic region (i.e. at low stresses or temperatures) when sufficient dispersion of the nanotubes is achieved. Interestingly enough, creep resistance increases in the non-linear viscoelastic region (i.e. at high stresses or temperatures) regardless of the degree of nanotube dispersion in the matrix. This phenomenon is attributed to nanotube orientation induced by high levels of stress.

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Chen, Jia. "Modified Yttrium Hydroxide/MC Nylon Nanocomposites and Scaling Effects in Multilayer Polyethylene Films." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6073.

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In this thesis, monomer casting (MC) nylon was synthesized. MC nylon could replace nonferrous metals in certain applications, including gears, wheels, and other moving parts. However, compared with metals, MC nylon products have poor strength and stiffness, and crack easily, especially at low temperatures. In addition, the dimensional stability of MC nylon is poor, especially in the large casting nylon products, causing significant internal stresses due to shrinkage. Thus, MC nylon cracks easily when cast and molded. The yttrium hydroxide particles were modified by stearic acid and dispersed in the caprolactam. The polymerization time was short due to fast anionic polymerization. Copolymerization with different ratios of yttrium hydroxide particles can be used to prepare the copolymer. The effects of different amounts of yttrium hydroxide on the performance of the monomer casting nylon were studied. The products were characterized using X-ray diffraction, impact, and tensile testing. When the percentage of modified yttrium hydroxide is 0.3 wt %, the composite exhibits the maximum impact strength, thus the 0.3 wt % of modified yttrium hydroxide is the suitable percentage to enhance the impact strength of MC nylon. Transparency and color of polyethylene film layered packages change with the number of layers. When polyethylene layer thickness is between 50 µm and 200 µm, each additional subsequent layer in the package leads to an abrupt change of color and transparency. Polarized light optical effects can be used to manufacture packaging films and labels with forgery protection. A significant influence of the scaling factor on the latent effect and optical properties of the film package is demonstrated for 1 to 6 layers with the total thickness of 200±50 µm. Prior thermal treatment of individual layers before they are assembled into a package or assembled package heat treatment change the laminate color. This allows hidden marking and recording text or graphics on the multi-layer films, not visible under normal lighting conditions, but appearing when viewed in polarized light, or through the polarizer.

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20

Kosuri, Divya. "Polyethylene-layered double hydroxide and montmorillonite nanocomposites: Thermal, mechanical and flame retardance properties." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc6087/.

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The effect of incorporation two clays; layered double hydroxides (LDH) and montmorillonite layered silicates (MLS) in linear low density polyethylene (PE) matrix was investigated. MLS and LDH were added of 5, 15, 30 and 60 weight percent in the PE and compounded using a Brabender. Ground pellets were subsequently compression molded. Dispersion of the clays was analyzed using optical microscopy, SEM and XRD. Both the layered clays were immiscible with the PE matrix and agglomerates formed with increased clay concentration. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Both clays served as nucleation enhancers increasing recrystallization temperatures in the composites. Flame retarding properties were determined by using the flammability HVUL-94 system. LDH indicated better flame retarding properties than MLS for PE. The char structure was analyzed by environmental scanning electron microscopy. Mechanical properties were studied by tensile testing and Vickers microhardness testing apparatus.

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21

Labde, Rohan Khushal. "Preparation and Characterization of Polyethylene Terephthalate/Montmorillonite Nanocomposites by In-situ Polymerization Method." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1271126238.

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22

Kosuri, Divya D'Souza Nandika Anne. "Polyethylene-layered double hydroxides and montmorillonite nanocomposites thermal, mechanical and flame retardance properties /." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-6087.

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23

Kanbur, Yasin. "Conductive Polymer Nanocomposites Of Polypropylene And Organic Field Effect Transistors With Polyethylene Gate Dielectric." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613312/index.pdf.

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One of the aim of this study is to prepare conductive polymer nanocomposites of polypropylene to obtain better mechanical and electrical properties. Composite materials based on conductive fillers dispersed within insulating thermoplastic matrices have wide range of application. For this purpose, conductive polymer nanocomposites of polypropylene with nano dimentional conductive fillers like carbon black, carbon nanotube and fullerene were prepared. Their mechanical, electrical and thermal properties were investigated. Polypropylene (PP)/carbon black (CB) composites at different compositions were prepared via melt blending of PP with CB. The effect of CB content on mechanical and electrical properties was studied. Test samples were prepared by injection molding and compression molding techniques. Also, the effect of processing type on mechanical and electrical properties was investigated. Composites become semiconductive with the addition of 2 wt% CB. Polypropylene (PP) / Carbon Nanotube (CNT) and Polypropylene / Fullerene composites were prepared by melt mixing. CNT&rsquo
s and fullerenes were surface functionalized with HNO3 : H2SO4 before composite preparation. The CNT and fullerene content in the composites were varied as 0.5, 1.0, 2.0 and 3.0 % by weight. For the composites which contain surface modified CNT and fullerene four different compatibilizers were used. These were selected as TritonX-100, Poly(ethylene-block-polyethylene glycol), Maleic anhydride grafted Polypropylene and Cetramium Bromide. The effect of surface functionalization and different compatibilizer on mechanical, thermal and electrical properties were investigated. Best value of these properties were observed for the composites which were prepared with maleic anhydride grafted polypropylene and cetramium bromide. Another aim of this study is to built and characterize transistors which have polyethylene as dielectric layers. While doing this, polyethylene layer was deposited on gate electrode using vacuum evaporation system. Fullerene , Pentacene ve Indigo were used as semiconductor layer. Transistors work with low voltage and high on/off ratio were built with Aluminum oxide - PE and PE dielectrics.

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24

Nawaz, Sohail. "Preparation and long-term performance of poly(ethylene-co-butyl acrylate) nanocomposites and polyethylene." Doctoral thesis, KTH, Polymera material, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104685.

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The current study discusses the preparation and long-term performance of polymer composites used for various purposes under different ageing conditions. The first part deals with the preparation and characterization of polymer nanocomposites based on poly(ethylene-co-butyl acrylate) (EBA–13 and EBA–28 with 13 and 28 wt % butyl acrylate, respectively) and 2–12 wt % (0.5–3 vol %) of aluminum oxide nanoparticles (two types with different specific surface areas and different hydroxyl-group concentrations; uncoated and coated with, respectively, octyltriethoxysilane and aminopropyltriethoxysilane). The nanocomposite with EBA–13 showed better overall nanoparticle dispersion while EBA–28 resulted in poor dispersion, probably due to insufficiently high shear forces acting during extrusion mixing which were unable to break down nanoparticle agglomerates. The activity of hindered phenolic antioxidant (0.2 wt%) in all EBA nanocomposites was assessed by determining the oxidation induction time using DSC. The composites containing uncoated aluminium oxide nanoparticles showed a much shorter initial OIT than the pristine polymer with the same initial concentration of antioxidant, indicating adsorption of antioxidant onto the nanoparticle surfaces. Composites containing coated nanoparticles showed a significantly smaller decrease in the initial OIT, suggesting the replacement of hydroxyl groups with organic silane tails, decreasing the concentration of available adsorption sites on the nanoparticle surfaces. The decrease in OIT with increasing ageing time in dry air at 90 °C of the nanocomposites was slower than that of the unfilled pristine polymer, suggesting a slow release of antioxidant from adsorption sites. The EBA nanocomposites exposed to liquid water at 90°C showed faster decrease of OIT than samples exposed to dry or humid air. The migration rate of antioxidant was controlled by the boundary conditions in the case of ageing in humid air and liquid water. The antioxidant diffusivity was lower for the composites containing uncoated ND than for the composites containing ND coated with octyltriethoxysilane or aminopropyltriethoxysilane. The migration and chemical consumption of deltamethrin DM, (synthetic pyrethroid) and synergist piperonyl butoxide from molded polyethylene sheets was also studied. Deltamethrin and piperonyl butoxide are often used for food storage and insect control purposes. DM showed no signs of crystallization and remained in a liquid state after being cooled to room temperature. Exposure of polyethylene compound sheets to liquid water (at 80 & 95 °C), caused degradation and hydrolysis of the ester bond in the DM, present in the prepared material, and generated species containing hydroxyl groups. Liquid chromatography and infrared spectroscopy showed a significant migration of the active species in liquid water, whereas in air at 80 °C (60 and 80 %RH) the loss of DM and PBO was negligible over 30 days. The long-term performance of medium-density polyethylene stabilized with six different phenolic antioxidants (0.1 wt%) in aqueous chlorinated media at 70 °C was studied. The results were compared with data for previously studied solutions of antioxidants in squalane (a liquid, low molar mass analogue of polyethylene). A linear relationship was established between the time to reach antioxidant depletion in polyethylene tape samples and the time in squalane samples. Infrared spectroscopy and scanning electron microscopy of drawn samples revealed the onset of surface oxidation and surface embrittlement in tape samples exposed beyond the time for antioxidant depletion.

QC 20121109

Cable insulation materials
Loss of deltamethrin and pipronyl butoxide from polyethylene
long-term performance of polyethylene in chlorine dioxide water

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25

Isik, Coskunses Fatma. "Ternary Nanocomposites Of Low Density,high Density And Linear Low Density Polyethylenes With The Compatibilizers E-ma_gma And E-ba-mah." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613294/index.pdf.

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The effects of polyethylene, (PE), type, compatibilizer type and organoclay type on the morphology, rheological, thermal, and mechanical properties of ternary low density polyethylene (LDPE), high density polyethylene (HDPE), and linear low density polyethylene (LLDPE), matrix nanocomposites were investigated in this study. Ethylene &ndash
Methyl acrylate &ndash
Glycidyl methacrylate terpolymer (E-MAGMA) and Ethylene &ndash
Butyl acrylate- Maleic anhydrate terpolymer (E-BA-MAH) were used as the compatibilizers. The organoclays selected for the study were Cloisite 30B and Nanofil 8. Nanocomposites were prepared by means of melt blending via co-rotating twin screw extrusion process. Extruded samples were injection molded to be used for material characterization tests. Optimum amounts of ingredients of ternary nanocomposites were determined based on to the mechanical test results of binary blends of PE/Compatibilizer and binary nanocomposites of PE/Organoclay. Based on the tensile test results, the optimum contents of compatibilizer and organoclay were determined as 5 wt % and 2 wt %, respectively. XRD and TEM analysis results indicated that intercalated and partially exfoliated structures were obtained in the ternary nanocomposites. In these nanocomposites E-MA-GMA compatibilizer produced higher d-spacing in comparison to E-BA-MAH, owing to its higher reactivity. HDPE exhibited the highest basal spacing among all the nanocomposite types with E-MA-GMA/30B system. Considering the polymer type, better dispersion was achieved in the order of LDPE<
LLDPE<
HDPE, owing to the linearity of HDPE, and short branches of LLDPE. MFI values were decreased by the addition of compatibilizer and organoclay to the matrix polymers. Compatibilizers imparted the effect of sticking the polymer blends on the walls of test apparatus, and addition of organoclay showed the filler effect and increased the viscosity. DSC analysis showed that addition of compatibilizer or organoclay did not significantly affect the melting behavior of the nanocomposites. Degree of crystallinity of polyethylene matrices decreased with organoclay addition. Nanoscale organoclays prevented the alignment of polyethylene chains and reduced the degree of crystallinity. Ternary nanocomposites had improved tensile properties. Effect of compatibilizer on property enhancement was observed in mechanical results. Tensile strength and Young&rsquo
s modulus of nanocomposites increased significantly in the presence of compatibilizers.

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26

Costa, Francis Reny. "Mg-Al Layered Double Hydroxide: A Potential Nanofiller and Flame-Retardant for Polyethylene." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1195481811992-27563.

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The presented research report deals with the investigation of magnesium aluminum based layered double hydroxide (LDH) as a potential nanofiller and flame-retardant for polymers with special reference to polyethylene. LDH is a mixed hydroxide of di- and trivalent metal ions that crystallizes in the form of mineral brucite. The basic reason for selecting LDH or more specifically magnesium-aluminum based LDH (Mg-Al LDH) is their typical metal hydroxide-like chemistry and conventional clay-like layered crystalline structure. The former is helpful in the direct participation in flame inhibition through endothermic decomposition and stable char formation. On the other hand, the later makes LDH suitable for polymer nanocomposite preparation, which can address the poor dispersibility problem associated with conventional metal hydroxide type fillers in polyolefin matrix. Besides, unlike layered silicate type clays (often reported for their capability to improve flame retardancy of polymers), LDH being reactive during combustion has higher efficiency to reduce the heat released during combustion of the composites. LDH clay with fixed Al:Mg ratio was synthesized using urea hydrolysis method and characterized. The organic modification of Mg-Al LDH using anionic surfactants has been studied in details. The main purpose of such modification is to enlarge the interlayer distance and to render it more organophilic. The surfactants were selected based on their functionality, chain length, etc and the modification was carried out by regeneration method. In the modified LDHs, the surfactants anions are arranged as a monolayer in the interlayer region and expand the interlayer distance according to their tail size. PE/LDH nanocomposites were prepared by melt-compounding method using a co-rotating tightly intermeshed twin-screw extruder and the morphological, mechanical and flammability properties of the nanocomposites were investigated in details. The X-ray diffraction analysis and electron microscopic analysis show a complex LDH particle morphology with hierarchy of particle size and shape starting from exfoliated particles fragments to particle aggregates over few hundred nm size. The exfoliated LDH platelets are distributed both in the vicinity of large particles and also in the bulk matrix. The melt rheological characterization of the nanocomposites also reflects the similar complex particle morphology. The dynamic oscillatory shear experiments showed that with increasing LDH concentration, the rheological behavior of the nanocomposite melts deviates strongly from that of the unfilled polyethylene. Thermogravimetric analysis (TGA) shows that LDH significantly improves the thermal stability of the polymer matrix in comparison to the unfilled polymer. The flammability studies of the PE/LDH nanocomposites have been reported in terms of various standard methods, like limited oxygen index (LOI), cone-calorimetry and UL-94 vertical and horizontal burn tests. The cone-calorimetric investigation shows that the nanocomposites have significantly lower burning rate and heat released during combustion. With increasing concentration of LDH though the LOI value of the nanocomposite increases marginally, the burning behavior, like dripping, rate of burning, etc are significantly improved. The flammability performance of LDH in combination with other commonly used flame-retardant (magnesium hydroxide) was also investigated. It has been observed that in polyethylene, a 50 wt% combination filler (4:1 weight ratio of magnesium hydroxide and LDH) can provide similar flammability ratings (like V0 rating in UL94 test, no dripping, etc) as that observed with 60 wt% magnesium hydroxide alone.

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27

Kim, Sung-gi. "PET Nanocomposites Development with Nanoscale Materials." Connect to Online Resource-OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1178043237.

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Dissertation (Ph.D.)--University of Toledo, 2007.
Typescript. "Submitted as partial fulfillment of the requirements for The Doctor of Philosophy Degree in Engineering." Bibliography: leaves 200-205.

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28

Svensson, Sofie. "Reprocessing and Characterisation of High Density Polyethylene Reinforced with Carbon Nanotubes." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-12853.

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Nanokomposit innehållande högdensitetspolyeten och kolnanorör återvanns och analyseradesför att undersöka hur materialets egenskaper påverkas av återvinning. Kompositenproducerades med 3 viktprocent kolnanorör och återvanns tio gånger genom att extrudera ochmala ner materialet. Analyser gjordes efter varje cykel av extrudering. Dessutom utfördessimulerade tester med kontinuerlig extrudering i 20, 100 och 200 minuter motsvarande 10, 50och 100 cykler. Därav kunde nedbrytningen av kompositen efter längre tids bearbetninganalyseras. I projektet studerades ett referensmaterial bestående av den rena polymeren för attkunna jämföra resultat. Karaktärisering av materialen för att bestämma mekaniska egenskapergjordes med dragprovning, böjningstest och slagprovning. För att undersöka termiskaegenskaper användes Differential Scanning Calorimetry (DSC) och Gel PermeationChromatography (GPC) användes för att hitta molekylviktsändringar. Fourier TransformInfrared Spectroscopy (FTIR) utfördes för att identifiera materialet. Resultaten visade ingenstörre skillnad i egenskaper efter tio återvinningscykler, vilket indikerade att materialet harförmåga att behålla sina egenskaper vid återvinning. I de simulerade cyklerna minskade denoxidativa induktionstiden efter 50 och 100 cykler, vilket berodde på att antioxidanterkonsumerats under bearbetningen. Efter 50 simulerade cykler hade molekylvikten börjat sjunkaoch efter 100 cykler kunde en signifikant minskning obseveras, vilket tydde på attpolymerkedjorna förkortats under bearbetningen. För kompositen däremot var molekylviktenstabil, på grund av att kolnanorören skyddade polymeren vid nedbrytning.
Nanocomposite containing High Density Polyethylene (HDPE) and Carbon Nanotubes (CNTs)was reprocessed and characterised to investigate the effect on properties during recycling. Thecomposite was prepared with 3 wt-% CNTs and was recycled ten times by alternatereprocessing and grinding and thereafter the material was characterised. Furthermore, simulatedcycles with continuous processing at 20, 100 and 200 minutes were conducted, representing 10,50 and 100 cycles respectively, in order to investigate the degradation after longer time ofprocessing. In both trials, a reference material containing neat HDPE was studied. Thecharacterisation of the materials produced was conducted using tensile, flexural and charpyimpact testing for investigation of mechanical properties. Differential Scanning Calorimetry(DSC) was used for determining the thermal behaviour and Gel Permeation Chromatography(GPC) to find molecular weight changes. Fourier Transform Infrared Spectroscopy (FTIR) wasused for identification of the material. The results showed no major difference in propertiesafter ten recycling steps, which indicated that the material had the ability to retain its propertiesduring recycling. In the simulated cycles, the oxidative induction time was decreased after 50and 100 cycles, meaning that antioxidants had been consumed during processing. After 50cycles the molecular weight for the reference material was slightly decreased and after 100cycles significantly decreased, indicating chain scission of the polymer chains. For thecomposite the molecular weight was stable, due to that the carbon nanotubes protect thepolymer matrix during degradation.

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29

Zhang, Qilei. "Preparation of high-strength and high-modulus HA/UHMWPE nanocomposites for cortical bone replacement /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CBME%202008%20ZHANG.

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30

Vaddi, Satya. "Flammability evaluation of glass fiber reinforced polypropylene and polyethylene with montmorillonite nanoclay additives." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2009r/vaddi.pdf.

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Thesis (M.S.)--University of Alabama at Birmingham, 2008.
Title from PDF title page (viewed Feb. 1, 2010). Additional advisors: Derrick R. Dean, Gregg M. Janowski, Selvum (Brian) Pillay (ad hoc). Includes bibliographical references (p. 76-82).

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31

Bueno, Marcos Roberto Paulino. "Materiais nanoestruturados sintéticos tipo esmectitas: sua síntese, caracterização e aplicação em nanocompósitos de polietileno." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/24325.

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Materiais naturais nanoestruturados, tipo smectita, têm sido amplamente usados em nanocompósitos poliméricos, com ganhos expressivos em muitas propriedades. Porém, devido a sua natureza polar, seu uso em nanocompósitos de poliolefinas apresenta uma série de problemas. Entre esses problemas está a dificuldade de esfoliação na matriz, o que geralmente resulta um sistema não nano-estruturado e, por conseqüência, com pouco ou nenhum ganho em propriedades. Para tentar resolver esse problema, materiais tipo esmectita têm sido modificados com sais de amônio quartenário. Esses, por sua vez, possuem características tóxicas, impedindo seu uso em embalagens de alimentos. Com o objetivo de estudar uma nova alternativa que contorne esses problemas, dois materiais lamelares nano-estruturados, tipo esmectita, contendo grupos alquila ligados por ligação sigma com a rede inorgânica, foram sintetizados. Ambos apresentaram excelente ordem mesoestrutural. Um dos materiais sintetizados, formado por um Alsilsesquioxano lamelar, contendo alto teor de cadeia alquila entre as lamelas inorgânicas, foi usado na formação de compósito de polietileno. Comparativamente, uma argila natural, modificada com sais de amônio quaternário (Cloisite 15A), foi usada para fins comparativos. Os compósitos, então obtidos, foram caracterizados para avaliar diferenças microestruturais, morfológicas e mudanças em suas propriedades mecânicas e reológicas. Comparativamente à argila comercial Cloisite 15A, os compósitos contendo os materiais sintéticos apresentaram reologia diferenciada, melhor resistência ao impacto e ao Tensofissuramento Acelerado pelo Ambiente (ESCR).
Nanostructured natural materials, as smectites, have been widely used in polymeric nanocomposites, with significant gains in many properties. However, due to its polar nature, the use in nanocomposites of polyolefins presents a series of drawbacks. Among these problems, its difficulty exfoliation in the matrix, which generally results in a system not nanostructured and, consequently, with little or no gain on properties. To try to resolve this problem, materials type smectite have been modified with quaternary ammonium salts. These salts, in turn, have toxic characteristics, preventing its use in food packaging. In order to study a new alternative that bypasses these problems, two lamellar nanostructured materials, like smectite, with alkyl groups containing sigma links connected to lamellar inorganic network, were synthesized. Both materials had excellent mesostructural order. One of the synthesized materials, formed by a lamellar Al-silsesquioxane, containing high levels of alkyl chain between the inorganic lamella, was used in the formation of a polyethylene composite. Commercial natural clay, modified with quaternary ammonium salts (Cloisite 15A), was used for comparative purposes. The composites then obtained, were characterized to assess microstructural differences, morphological change, and its mechanical and rheological properties. Comparatively to commercial clay (Cloisite 15A), the composites containing synthetic materials, showed differented rheologics properties, better impact resistance and better Environmental Stress Cracking Resistance (ESCR).

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32

Ersu, Dilek. "Preparation And Characterization Of Nanocomposites With A Thermoplastic Matrix And Spherical Reinforcement." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607447/index.pdf.

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The aim of this study is to investigate the effects of compatibilizers, fumed silica and mixing order of components on morphological, thermal, mechanical and flow properties of LDPE/Fumed silica nanocomposites. As compatibilizer(Co)
ethylene/n-butyl acrylate/maleic anhydride (E-nBA-MAH), ethylene/glycidyl methacrylate (E-GMA) and ethylene/methyl acrylate/glycidyl methacrylate (E-MA-GMA) Lotader®
resins
as silica Cab-o-sil®
M5 fumed silica were used. All samples were prepared by means of a lab scale co-rotating twin screw extruder and injection molded into standard samples. In the first step, individual effects of filler and compatibilizers were studied in binary systems with LDPE. Then, keeping the amount of compatibilizer constant at 5%, ternary nanocomposites were prepared by adding 2 or 5% of fumed silica using different component mixing orders. Among investigated mixing orders, mechanical test results showed that the best sequences of component addition are FO1 [(LDPE+Co)+M5] and FO2 [(LDPE+M5)+Co] mixing orders. Considering the compatibilizers, E-nBA-MAH terpolymer showed the highest performance in improving the mechanical properties, E-GMA copolymer also gave satisfactory results. According to the DSC analysis, since addition of fumed silica and compatibilizer does not influence the crystallization behavior of the compositions, it is concluded that, neither fumed silica nor any of the compatibilizers have nucleation activity on LDPE. MFI test results showed that, addition of fumed silica increases the melt viscosity, decreasing MFI values of samples. This change seems to be directly proportional to fumed silica amount.

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33

Tijen, Seyidoglu. "Purification And Modification Of Bentonite And Its Use In Polypropylene And Linear Low Density Polyethylene Matrix Nanocomposites." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612204/index.pdf.

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The potential use of Resadiye/Tokat bentonite as a reinforcement in polypropylene (PP) and linear low density polyethylene (LLDPE) polymer matrix nanocomposites filler was investigated. At first, organoclays (OC) were prepared by cation exchange reaction (CER) between the raw bentonite (RB) and three quaternary ammonium salts with long alkyl tails (QA): hexadecyl trimethyl ammonium bromide [HMA] [Br], tetrabutyl ammonium tetrafluoroborate [TBA] [BF4], tetrakisdecyl ammonium bromide [TKA] [Br] and one quaternary phosphonium (QP) salt: tetrabutyl phosphonium tetrafluroborate [TBP] [BF4]. Characterization of resulting materials by XRD, TGA, FTIR and chemical analysis confirmed the formation of organoclays. Ternary composites of PP/organoclay/ maleic anhydride grafted polypropylene (MAPP) were prepared with two different grades of PPs in a co-rotating twin screw extruder. Composites prepared with these organoclays and PPs showed microcomposite formation. In the second part of the study, raw bentonite was purified by sedimentation, and characterization of purified bentonite (PB) by XRD, cation exchange capacity (CEC) measurement and chemical analysis (ICP) confirmed the success of purification method. PB was then modified with two QA`s: dimethyl dioctadecylammonium chloride [DMDA] [Cl], tetrakis decylammonium bromide [STKA] [Br] and one QP: tributyl hexadecyl phosphonium bromide [TBHP] [Br]. Organoclays from PB were used with the PP with lower viscosity, and ternary nanocomposites (PP/Organoclay2/MAPP5) were prepared in the extruder followed by batch mixing in an intensive batch mixer. Use of DMDA and TBHP OCs resulted in nanocomposite formation, while STKA resulted in microcomposite formation as observed by XRD and TEM. Young`s modulus and yield stress of the samples were enhanced through nanocomposite formation. In the last part of the study, ternary composites of LLDPE/Organoclay/ compatibilizer, a random terpolymer of ethylene, butyl acrylate and maleic anhydride (E-BA-MAH, Lotader®
3210), were prepared by melt compounding in the batch mixer at two different clay concentrations (2 and 5 wt %) and fixed compatibilizer/organoclay ratio (&alpha
=2.5). A commercial organoclay, I34, was also used in LLDPE based nanocomposites to make a comparison. XRD and TEM analyses of the compounds prepared by DMDA and TBHP showed mixed nanocomposite morphologies consisting of partially intercalated and exfoliated layers. Young`s modulus and tensile strength of nanocomposites prepared with DMDA and TBHP showed generally higher values compared to those of neat LLDPE, while results were the highest in the composites prepared with commercial organoclay I34. Parallel disk rheometry was used as a supplementary technique to XRD, TEM and mechanical characterizations, and it was shown to be a sensitive tool in assessing the degree of dispersion of clay layers in the polymer matrix.

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34

Pallon, Love. "Polyethylene/metal oxide nanocomposites for electrical insulation in future HVDC-cables : probing properties from nano to macro." Doctoral thesis, KTH, Polymera material, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193591.

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Nanocomposites of polyethylene and metal oxide nanoparticles have shown to be a feasible approachto the next generation of insulation in high voltage direct current cables. In order to reach an operationvoltage of 1 MV new insulation materials with reduced conductivity and increased breakdown strengthas compared to modern low-density polyethylene (LDPE) is needed.In this work polyethylene MgO nanocomposites for electrical insulation has been produced andcharacterized both from an electrical and material perspective. The MgO nanoparticles weresynthesized into polycrystalline nanoparticles with a large specific surface area (167 m2 g–1). Meltprocessing by extrusion resulted in evenly dispersed MgO nanoparticles in LDPE for the silane surfacemodified MgO as compared to the unmodified MgO. All systems showed a reduction in conductivityby up to two orders of magnitude at low loading levels (1–3 wt.%), but where the surface modifiedsystems were able to retain reduced conductivity even at loading levels of 9 wt.%. A maximuminteraction radius to influence the conductivity of the MgO nanoparticles was theoretically determinedto ca. 800 nm. The interaction radius was in turn experimentally observed around Al2O3 nanoparticlesembedded in LDPE using Intermodulation electrostatic force microscopy. By applying a voltage on theAFM-tip charge injection and extraction around the Al2O3 nanoparticles was observed, visualizing theexistence of additional localized energy states on, and around, the nanoparticles. Ptychography wasused to reveal nanometre features in 3D of electrical trees formed under DC-conditions. Thevisualization showed that the electrical tree grows by pre-step voids in front of the propagatingchannels, facilitating further growth, much in analogy to mechanical crack propagation (Griffithconcept). An electromechanical effect was attributed as possible mechanism for the formation of the voids.
Nanokompositer av polyeten och metalloxidpartiklar anses vara möjliga material att använda i morgondagens isolationshölje till högspänningskablar för likström. För att nå en transmissionsspänning på 1 MV behövs isolationsmaterial som i jämförelse med dagens polyeten har lägre elektrisk ledningsförmåga, högre styrka mot elektriskt genomslag och som kan kontrollera ansamling av rymdladdningar. De senaste årens forskning har visat att kompositer av polyeten med nanopartiklar av metalloxider har potential att nå dessa egenskaper. I det här arbetet har kompositer av polyeten och nanopartiklar av MgO för elektrisk isolation producerats och karaktäriserats. Nanopartiklar av MgO har framställts från en vattenbaserad utfällning med efterföljande calcinering, vilket resulterade i polykristallina partiklar med en mycket stor specifik ytarea (167m2 g-1). MgO-nanopartiklarna ytmodifierades i n-heptan genom att kovalent binda oktyl(trietoxi)silan och oktadekyl(trimetoxi)silan till partiklarna för att skapa en hydrofob och skyddande yta. Extrudering av de ytmodifierade MgO nanopartiklarna tillsammans med polyeten resulterade i en utmärkt dispergering med jämnt fördelad partiklar i hela kompositen, vilket ska jämföras med de omodifierade partiklarna som till stor utsträckning bildade agglomerat i polymeren. Alla kompositer med låg fyllnadsgrad (1–3 vikt% MgO) visade upp till 100 gånger lägre elektrisk konduktivitet jämfört med värdet för ofylld polyeten. Vid högre koncentrationer av omodifierade MgO förbättrades inte de isolerande egenskaperna på grund av för stor andel agglomerat, medan kompositerna med de ytmodifierade fyllmedlen som var väl dispergerade behöll en kraftig reducerad elektrisk konduktivitet upp till 9 vikt% fyllnadshalt. Den minsta interaktionsradien för MgO-nanopartiklarna för att minska den elektriska konduktiviten i kompositerna fastställdes med bildanalys och simuleringar till ca 800 nm. Den teoretiskt beräknade interaktionsradien kompletterades med observation av en experimentell interaktionsradie genom att mäta laddningsfördelningen över en Al2O3-nanopartikle i en polyetenfilm med intermodulation (frekvens-mixning) elektrostatisk kraftmikroskop (ImEFM), vilket är en ny AFM-metod för att mäta ytpotentialer. Genom att lägga på en spänning på AFM-kantilevern kunde det visualiseras hur laddningar, både injicerades och extraherades, från nanopartiklarna men inte från polyeten. Det tolkades som att extra energinivåer skapades på och runt nanopartiklarna som fungerar för att fånga in laddningar, ekvivalent med den gängse tolkningen att nanopartiklar introducera extra elektronfällor i den polymera matrisen i nanokompositer. Nanotomografi användes för att avbilda elektriska träd i tre dimensioner. Avbildningen av det elektriska trädet visade att tillväxten av trädet hade skett genom bildning av håligheter framför den framväxande trädstrukturen. Håligheterna leder till försvagning av materialet framför det propagerande trädet och förenklar på det sättet fortsatt tillväxt. Bildningen av håligheter framför trädstrukturen uppvisar en analogi till propagering av sprickor vid mekanisk belastning, i enlighet med Griffiths koncept.

QC 20161006

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Kanuga, Karnav D. "A FUNDAMENTAL STUDY ON THE NON-LINEAR MECHANO-OPTICAL BEHAVIOR OF POLYETHYLENE NAPHTHALATE, ITS BLENDS WITH POLYETHERIMIDE AND ITS NANOCOMPOSITES." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1138038431.

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Coelho, Paulo Henrique da Silva Leite 1985. "Estudo do efeito de compatibilização de argilas organofílicas em blendas imiscíveis de poliamida 6 e polietileno de baixa densidade." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266910.

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Orientador: Ana Rita Morales
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: O trabalho descreve a obtenção de nanocompósitos de polietileno de baixa densidade, poliamida 6, polietileno enxertado com anidrido maleico e montmorilonita organofilicamente modificada com o objetivo de estudar o efeito de compatibilização da argila organofílica nas blendas de polietileno e poliamida. Os compostos foram preparados pelo método de intercalação do fundido em extrusora dupla-rosca e os corpos de prova, obtidos por injeção, foram caracterizados por análise térmica dinâmico-mecânica, microscopia eletrônica de varredura, difração de raios-X, microscopia eletrônica de transmissão, calorimetria exploratória diferencial, análise termogravimétrica e teste mecânicos de resistência a tração e ao impacto. As análises térmicas revelaram uma ligeira queda da estabilidade térmica associada ao efeito de degradação do modificador encontrado na argila; o aparecimento de um novo pico de fusão nas curvas de DSC dos nanocompósitos foi associado à formação de uma nova fase cristalina na poliamida 6, causado pela presença da argila. As análises morfológicas revelaram uma adequada homogeneidade nos nanocompósitos e uma redução dos tamanhos dos domínios das duas fases da blenda, de forma que nenhum aglomerado foi observado, o que mostra que houve uma boa dispersão da argila na matriz. As análises estruturais confirmaram esta boa dispersão através da microscopia eletrônica de transmissão (MET) e da difração de raios-X (DRX), que revelaram que a argila teve suas camadas parcialmente intercaladas e/ou esfoliadas em todos os nanocompósitos estudados, e que esta estrutura encontrada proporcionou uma melhora significativa nas propriedades mecânicas dos compostos
Abstract: This work describes the behavior of nanocomposites of polyamide 6 (PA6), low density polyethylene (LDPE) and an organophilic montmorillonite. The compatibilization effect of the orgalophilic clay was studied with and without the presence of a maleic anhydride grafted polyethylene (PE-g-MA). The nanocomposites were prepared by melt intercalation on a twin screw extruder. The samples were prepared by injection molding, and characterized using scanning electron microscopy (SEM), wide-angle X-diffraction (WAXD), dynamic mechanical analysis (DMA), transmission electron microscopy (TEM) and differential scanning calorimeter (DSC). Mechanical properties as tensile strength and impact strength were also evaluated. The thermal analysis showed a slight decrease in thermal stability that was associated with the effect of degradation of the modifier of the clay; the emergence a new melting peak for the Polyamide 6 associated to a new crystalline phase due the clay nucleation effect. The morphologic analysis showed two phases for all systems but a reduction on the particle dimension due the presence of the clay, with low differences by the use of the compatibilizer. Structural analysis confirmed by transmission electron microscopy (TEM) and X-ray diffraction (XRD), which had its clay layers extensive exfoliated, with some small degree of intercalation nanocomposites at all, and that this structure has provided a significant improvement in mechanical properties of compounds
Mestrado
Ciencia e Tecnologia de Materiais
Mestre em Engenharia Química

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37

Carvalho, José Wilson Camilher. "Estudo, caracterização e aplicação de nanocompósitos utilizando poliolefinas funcionalizadas." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266883.

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Orientador: Lúcia Helena Innocentini Mei
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: É apresentada a preparação e a caracterização de nanocompósitos, produzidos a partir da vermiculita e poliolefinas funcionalizadas como matriz polimérica. As poliolefinas foram representadas pelo polietileno de baixa densidade (PEBD) e o polietileno de baixa densidade linear (PEBDL), utilizadas com e sem o anidrido maleico. A vermiculita de origem nacional foi escolhida como fase inorgânica na preparação dos nanocompósitos, devido a sua abundância e o seu baixo custo associado. A interação das matrizes poliolefínicas com a vermiculita foi facilitada pela utilização de agentes de acoplamento, baseados em compostos de amônio, cujos efeitos sobre as propriedades de barreira, ao oxigênio, à umidade, e de retardância de chama dos compostos obtidos são relatados. Foi utilizada como ferramenta de análise a Espectroscopia de Infravermelho com transformada de Fourier (FTIR), para o acompanhamento e caracterização do processo de síntese das organo-vermiculitas. A Difração de Raio X (DRX) foi utilizada tanto para a análise do minério de vermiculita como recebido, quanto para a caracterização dos nanocompósitos utilizando as vermiculitas modificadas com os agentes de acoplamento. Os resultados foram confirmados com a utilização da Microscopia Eletrônica de Transmissão (MET) e a Microscopia Eletrônica de Varredura (MEV), com auxílio da técnica de feixe de íons (FIB). Essas técnicas confirmaram a obtenção de compostos esfoliados, evidenciando a eficiência dos agentes de acoplamento no processo de obtenção dos nanocompósitos, previamente analisados via DRX. A estrutura esfoliada dos compostos obtidos permitiu que fossem conduzidos testes sobre a sua capacidade de barreira ao oxigênio e a umidade, cujos resultados promissores mostraram a possibilidade de serem utilizados como materiais de embalagem. Da mesma forma, a característica esfoliada destes materiais possibilitou o desenvolvimento de testes para o atendimento da área de fios e cabos como isolamento e cobertura de cabos. Com este objetivo, foram analisados os requisitos de retardância de chama e ao aumento da temperatura de degradação, fundamental à preservação da integridade dos cabos durante o ataque das chamas. Este trabalho apresentou de maneira pioneira o processo de produção e utilização da vermiculita nacional, na obtenção de nanocompósitos, desde minério bruto até o produto final e a sua aplicação em casos reais
Abstract: The preparation and characterization of nanocomposites made from vermiculite and functionalized polyolefins as a polymeric matrix is presented. Polyolefins are represented by low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), used with and without maleic anhydride. Vermiculite from a national origin was chosen as an inorganic phase in the nanocomposite preparation, due to its abundance and low cost. The interaction of the polyolefin matrixes with the vermiculite was facilitated using coupling agents. The coupling agents used were represented by the ammonium compounds and their effects were reported in the barrier properties to oxygen, humidity and in flame retardance in the produced compounds. As a nanocomposite analysis tool, Fourrier transformed infrared spectroscopy (FTIR) techniques were used, mainly in following and characterizing the organo-vermiculite process. X-ray diffraction (XRD) was used from the analysis of the vermiculite as received to the nanocomposite characterization using coupling agents. These results were confirmed using the transmission electronic microscopy (TEM) and scanning electronic microscopy (SEM), using focused ion beam (FIB), as well. These techniques confirmed the obtainment of exfoliated compounds that reinforced the coupling agents in the nanocomposite obtainment process, previously analyzed by XRD. The exfolied structure of the compounds obtained allowed for barrier-capacity tests. The nanocomposites tested as an oxygen and humidity barrier showed the possibility of being used as packaging materials due to the promising results presented. Likewise, the exfoliated characteristic of these materials enabled the development of tests to meet the needs of the wire and cable area as insulation and cable jacketing. Within this objective, there was the need to focus on the flame retardance requirements and the increase of the degradation temperature, crucial to preserve cable integrity during the flame attack. This work presents, in a pioneering manner, a revision of the production process and utilization of national vermiculite in obtaining the nanocomposite, from its ore to the final product and its application in real cases
Doutorado
Ciencia e Tecnologia de Materiais
Doutor em Engenharia Química

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38

Ferreira, Santos Melo Ana Elisa. "New approaches for the synthesis of high-performance polyolefins reactor nanocomposites and blends." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0032/document.

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Malgré les propriétés remarquables de polyéthylène de masse molaire très élevée(UHMWPE), une généralisation de son application est limitée en raison des difficultésrencontrées lors de sa mise en forme, liées au taux d’enchevêtrement important deschaînes.Le but de ce travail est de développer des nanocomposites et des mélanges à base depolyéthylène, par polymérisation in situ. A cet effet, des catalyseurs métallocènes et despost-métallocènes ont été immobilisés par différentes méthodes sur la silice mésoporeuseSBA-15. Le système poreux de ce support, avec des canaux bien définis à l'échellenanométrique, peut entraîner des effets de confinement des chaînes macromoléculaireset/ou permettre un mélange intime des polymères.Le comportement de la polymérisation de l'éthylène par catalyses homogène et supporté,ainsi que les méthodes d'immobilisation utilisées et leur effet sur l'activité depolymérisation et des masses molaires, ont été évalués.Une caractérisation complète des nanocomposites et des mélanges comprenant différentsaspects des matériaux (morphologie, cristallinité et homogénéité) a été réalisée. Lespropriétés thermiques et mécaniques des matériaux finaux ont été également évaluées.D'une manière générale, les nanocomposites à base de polyéthylène et les mélanges enréacteur ont montré des propriétés mécaniques améliorées, en termes de moduled'élasticité, résistance mécanique, ténacité et résistance au fluage, par comparaison avec lespolyéthylènes communs. En traitant la poudre d'UHMWPE par moulage, par compression àhaute pression et au-dessous de sa température de fusion, une augmentation remarquabledes paramètres mécaniques a été obtenue.Les résultats préliminaires sur la préparation de nanocomposites en utilisant desnanocristaux de cellulose ont montré que cette approche est faisable et qu’elle présente unpotentiel de développement
Despite the remarkable properties of ultra-high molecular weight polyethylene, itsapplication is limited by the difficulties encountered in conventional melt processing duethe high degree of entanglement of the chains.The aim of this work is to develop polyethylene based nanocomposites and in-reactorblends, by in situ polymerization. For this purpose metallocenes and post-metallocenecatalysts were immobilized by different methods on mesoporous silica SBA-15. The poroussystem of this support, with well-defined channels at the nanometric scale, may causeconfinement effects of macromolecular chains and/or potentiate intimate mixing ofpolymer blends.Ethylene polymerization behavior of the homogeneous and the supported systems alongwith the immobilization methodologies used and their effect on the polymerization activityand polymer molar masses were evaluated.A complete characterization of the nanocomposites and blends comprising different aspectsof the materials properties (morphology, crystallinity and homogeneity) was carried out.The thermal and mechanical properties of the final materials were also evaluated.In a general way the polyethylene based nanocomposites and in-reactor blends showedimproved mechanical properties, in terms of elastic modulus, mechanical strength,toughness and creep resistance, when compared with neat polyethylenes. By processing theUHMWPE powders by compression molding, at high pressure and below its meltingtemperature a remarkable increase of the mechanical parameters was obtained.Preliminary results on the preparation of nanocomposites using cellulose nanowhiskershave shown that this approach is feasible and show potential for further development

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Mokashi, Vineet V. "Study of Mechanical Properties of Carbon Nanotubes and Nanocomposites by Molecular Simulations." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1109358015.

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40

Cerezo, Frances Therese, and francestherese_cerezo@hotmail com. "Thermal stability and mechanical property of polymer layered graphite oxide composites." RMIT University. Applied Sciences, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080627.161157.

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Polymer composites formed from layered fillers with high surface volume ratio show enhanced reinforcement. Graphite oxide is a high modulus material that can be separated into thin layers with high surface area. The aim of this study is to prepare polymer layered graphite oxide composites using functionalised polyolefin to enhance compatibility with various forms of layered graphite oxide in varying concentration. Functionalised polyolefins reinforced with layered graphite oxides and expanded graphite oxides were prepared using solution blending and melt blending methods. Three different mixing methods with varying shear intensity were employed to prepare polymer layered graphite oxide composites. The crystalline structure, thermal and mechanical properties of the prepared polymer layered graphite oxide composites was studied. Oxidised graphite prepared from the Staudenmaier method and its exfoliated form were dispersed in poly(ethylene-co-methyl acrylate-co-acrylic acid) (EMAA) via solution blending to prepare EMAA layered composites. The thermal stability was determined using thermogravimetric analysis. The EMAA layered composites showed higher thermal stability in comparison with pure EMAA. The mechanical properties of these EMAA layered composites were determined through dynamic mechanical analysis. Shear modulus, yield stress and storage modulus of EMAA in the presence of graphite oxide fillers decreased. A solution blending method was used to prepare poly(propylene-grafted-maleic anhydride) layered expanded graphite oxide composites (PPMA-EGO). Two types of PPMA-EGO were prepared using different mixing methods - low and high shear were employed. The effects of preparative mixing methods on the PPMA-EGO properties were investigated. The mechanical properties of PPMA-EGO obtained from dynamic mechanical analysis indicated that EGO had a reinforcing effect on the elastic behaviour of PPMA-EGO. This is due to strong interfacial adhesion between PPMA and EGO as a result of hydrogen bonding. The elastic behaviour of PPMA-EGO was affected by the surface area of graphite flakes. Low sheared PPMA-EGO elastic behaviour was found to be higher compared with that of high sheared PPMA-EGO. A melt blending method was used to prepare PPMA-EGO with varying EGO concentration. The interconnected network structure of EGO in the PPMA-EGO was not observed as shown by its scanning electron microscopy images. Thermogravimetric analysis of PPMA-EGO indicates increased decomposition temperature of the PPMA matrix. Dynamic mechanical analysis showed enhanced storage modulus of PPMA-EGO. The maximum elastic modulus of PPMA-EGO was observed at 3 %wt of EGO. The electrical conductivity of PPMA-EGO was measured only for EGO concentrations above 2 %wt. The EGO concentration was found to be the most critical factor in the enhancement of the electrical conductivity of PPMA-EGO. Wide angle X-ray diffraction analysis of all polymer layered graphite oxide composites revealed no change in interlayer spacing of graphite layers, indicating the absence of EMAA intercalation in the graphite layers. The crystallisation temperature and crystallinity of all polymer layered graphite oxide composites were determined using differential scanning calorimetry. The results indicated that graphite oxide and expanded graphite oxides acted as nucleating agents in inducing the crystallisation of functionalised polyolefin in the layered composites. However, the degree of crystallinity of functionalised polyolefin decreased in the layered composites.

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Abakar, Adam Omar. "Elaboration, structuration et propriétés rhéologiques de nanocomposites polymères modèles à base de Laponite." Phd thesis, Université du Maine, 2012. http://tel.archives-ouvertes.fr/tel-00756711.

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Ce travail concerne l'étude du comportement rhéologique de nanocomposites modèles à base de Laponite dans du polyoxyde d'éthylène ou des mélanges polyoxyde d'éthylène avec du polyméthacrylate de méthyle. L'influence des paramètres moléculaires, masse molaire de la matrice et mode de protection des particules sur les propriétés rhéologiques a été étudiée. La meilleure dispersion est obtenue à partir d'une solution, la dilution d'un mélange maître conduisant à des matériaux hétérogènes. Les mélanges POE/PMMA sont compatibles à l'état fondu dans toute la gamme de concentrations mais hétérogènes à température ambiante au-dessus de 30% en poids de particules. En diluant un mélange Laponite/PEO dans le PMMA, nous avons montré que ces domaines se concentrent en particules en dessous de 30% de PEO et qu'une cocontinuité de phases PEO contenant les particules et PMMA essentiellement pur est formée au-dessus de 30% de PEO. La présence des particules diminue fortement la cristallinité.

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SILVA, Eduardo de Mello. "Obtenção e caracterização de nanocompósitos na forma de filmes planos." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1044.

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O presente trabalho trata da obtenção e caracterização de filmes planos de PEBDL/bentonita com e sem a incorporação de um agente compatibilizante (PE-gMA). Os filmes foram obtidos por extrusão plana e suas propriedades mecânicas, de permeabilidade e térmicas foram avaliadas em função do teor (0 a 5% em massa) e do tipo de carga incorporada. Duas argilas foram utilizadas: a) uma bentonita de origem local (Paraibana) e b) uma argila organofílica comercial importada. A argila paraibana foi purificada e organofilizada antes de ser incorporada à matriz polimérica. As argilas utilizadas foram caracterizadas através da sua capacidade de troca catiônica (CTC), por difração de raios-x (DRX), por espectroscopia no infravermelho por transformada de Fourier (FTIR), análise da composição química por energia dispersiva (EDX), análise granulométrica e por análise termogravimétrica (TGA). Os nanocompósitos obtidos na forma de filmes planos foram caracterizados por DRX, microscopia eletrônica de varredura (MEV), permeabilidade ao vapor de água e aos gases O2 e CO2, propriedades mecânicas, análise termogravimétrica (TGA) e análise da calorimetria exploratória diferencial (DSC). Os filmes de nanocompósitos com compatibilizante apresentaram morfologia intercalada/parcialmente esfoliada e os filmes sem a presença do compatibilizante apresentaram morfologia compatível com a de nanocompósitos intercalados/microcompósitos. Os resultados das propriedades mecânicas mostraram que os filmes preparados com o agente compatibilizante apresentaram propriedades superiores à da matriz pura e às dos outros sistemas preparados. A presença do agente compatibilizante reduziu significativamente a permeabilidade ao vapor de água e a permeabilidade ao gás O2 nos filmes, mas os filmes sem a presença do agente compatibilizante apresentaram aumento desta propriedade quando comparados ao filme de PEBDL puro. As analises térmicas mostraram um aumento discreto da estabilidade térmica para os filmes de nanocompósitos preparados com o agente compatibilizante.
The present work deals with the manufactur and characterization of flat films of LLDPE/bentonite with and without the incorporation of a compatibilizing agent (PE-g-MA). The films were obtained by flat die extrusion and its mechanical, permeability and thermal properties were evaluated in function of clay content (0 to 5% by mass) and clay identity. Two clays were used: a) a local bentonite (from Paraiba) and b) an imported commercial organoclay. The local clay was purified and organophilized before being incorporated into the polymer matrix. The clays were characterized by cation exchange capacity (CEC), x-ray diffraction (XRD), spectroscopy Fourier transform infrared (FTIR), analysis, chemical composition by dispersive energy (EDX), particle size analysis and by thermogravimetric analysis (TG). Nanocomposites obtained as flat films were characterized by XRD, scanning electron microscopy (SEM), water vapor, O2 and CO2 gas permeability, mechanical properties, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The nanocomposite films with compatibilizer showed an intercalated/partially exfoliated morphology while the morphology of the films without compatibilizer was compatible with that of intercalated nanocomposites/microcomposites. The mechanical properties of the films prepared with the compatibilizer agent were higher than those of the neat matrix and the other systems prepared. Compatibilizing agent addition significantly reduced water vapor and O2 gas permeability in films, but the films without the presence of the compatibilizer showed an increase of this property when compared to pure LLDPE film. The influence of compatibilizer addition on CO2 permeability was small. Thermal analyzes showed a slight increase of thermal stability for the films of nanocomposites prepared with the compatibilizing agent.

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43

Pirondelli, Andrea. "Production and Electrical Characterization of Low Density Polyethylene-based Micro- and Nano-dielectrics containing Graphene Oxide, Functionalized Graphene and Carbon Black additives." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.

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Oggigiorno la ricerca di nuovi materiali per gradatori di campo da impiegarsi in accessori di cavi ha iniziato a studiare alcuni materiali nano dielettrici con proprietà elettriche non lineari con la tensione ed aventi proprietà migliorate rispetto al materiale base. Per questo motivo in questo elaborato si sono studiati materiali nanostrutturati a base di polietilene a bassa densità (LDPE) contenenti nano polveri di grafene funzionalizzato (G*), ossido di grafene (GO) e carbon black (CB). Il primo obiettivo è stato quello di selezionare e ottimizzare i metodi di fabbricazione dei provini. La procedura di produzione è suddivisa in due parti. Nella prima parte è stata utilizzatala tecnica del ball-milling, mentre nella seconda un pressa termica (thermal pressing). Mediante la spettroscopia dielettrica a banda larga (BDS) si sono misurate le componenti reali e immaginarie della permettività e il modulo della conducibilità del materiale, in tensione alternata. Il miglioramento delle proprietà rispetto al provino di base composto dal solo polietilene si sono ottenute quando il quantitativo delle nanopolveri era maggiore. Le misure sono state effettuate sia a 3 V che a 1 kV. Attraverso misurazioni di termogravimetria (TGA) si è osservato l’aumento della resistenza termica di tutti i provini, soprattutto nel caso quando la % di nanopolveri è maggiore. Per i provini LDPE + 0.3 wt% GO e LDPE + 0.3 wt% G* si è misurata la resistenza alle scariche parziali attraverso la valutazione dell’erosione superficiale dei provini. Per il provino contenente G* è stato registrato una diminuzione del 22% del volume eroso, rispetto al materiale base, mentre per quello contenente GO non vi sono state variazioni significative. Infine si è ricercata la resistenza al breakdown di questi ultimi tre provini sopra citati. Per la caratterizzazione si è fatto uso della distribuzione di Weibull. Lo scale parameter α risulta aumentare solo per il provino LDPE + 0.3 wt% G*.

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44

Jordens, Kurt. "Hybrid Inorganic-Organic Materials: Novel Poly(Propylene Oxide) Based Ceramers, Abrasion Resistant Sol-Gel Coatings for Metals, and Epoxy-Clay Nanocomposites. With an Additional Chapter On: Metallocene Catalyzed Linear Polyethylene." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/30194.

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The sol-gel process has been employed to generate hybrid inorganic-organic network materials. Unique ceramers were prepared based on an alkoxysilane functionalized soft organic oligomer, poly(propylene oxide) (PPO), and tetramethoxysilane (TMOS). Despite the formation of covalent bonds between the inorganic and organic constituents, the resulting network materials were phase separated, composed of a silicate rich phase embedded in a matrix of the organic oligomer chains. The behavior of such materials was similar to elastomers containing a reinforcing filler. The study focused on the influence of initial oligomer molecular weight, functionality, and tetramethoxysilane, water, and acid catalyst content on the final structure, mechanical and thermal properties. The sol-gel approach has also been exploited to generate thin, transparent, abrasion resistant coatings for metal substrates. These systems were based on alkoxysilane functionazized diethylenetriamine (DETA) with TMOS, which generated hybrid networks with very high crosslink densities. These materials were applied with great success as abrasion resistant coatings to aluminum, copper, brass, and stainless steel. In another study, intercalated polymer-clay nanocomposites were prepared based on various epoxy networks montmorillonite clay. This work explored the influence of incorporated clay on the adhesive properties of the epoxies. The lap shear strength decreased with increasing clay content. This was due to a reduction in the toughness of the epoxy. Also, the delaminated (or exfoliated) nanocomposite structure could not be generated. Instead, all nanocomposite systems possessed an intercalated structure. The final project involved the characterization of a series of metallocene catalyzed linear polyethylenes, produced at Phillips Petroleum. Polyolefins synthesized with such new catalyst systems are becoming widely available. The influence of molecular weight and thermal treatment on the mechanical, rheological, and thermal behavior was probed. Although the behavior of this series of metallocene polyethylenes was not unlike that of traditionally catalyzed materials, this work is one of the first comprehensive studies of these new linear polyethylenes. The main distinction between the metallocene and traditional Ziegler-Natta catalyzed polyethylenes is the narrow molecular weight distributions produced by the former (for this series of materials, 2.3< Mw ï¿¼ Mn <3.6).
Ph. D.

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45

Pitard, Domitille. "Étude de l'organisation à l'état solide et de la dynamique des chaines polymères dans les nanocomposites polyéthylène/POSS." Phd thesis, Université Paris-Est, 2008. http://tel.archives-ouvertes.fr/tel-00461664.

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Liées de façon covalente à des chaînes polymères, les nanoparticules POSS (polysilses-quioxanes polyédriques) permettent l'obtention de matériaux nanocomposites hybrides orga-nique/inorganique. Ces nanoparticules présentent deux intérêts majeurs: des dimensions bien définies (cœur inorganique: 0.5 nm), ainsi que leur caractère hybride ( groupements organiques entourant les cages inorganiques). Les nanocomposites polymère/POSS peuvent présenter un renfort important des propriétés mécaniques et de la stabilité thermique de la matrice polymère. Cependant, l'origine moléculaire de ce renfort reste mal comprise. Aussi, afin de mieux comprendre le renfort des propriétés mécaniques de la matrice, nous avons étudié l'effet des particules POSS sur l'organisation à l'état solide et la dynamique des chaînes po-lymères au sein d'une matrice semi-cristalline. Pour cela, nous avons considéré une série de copolymères polyéthylène-POSS, caractérisés par une large gamme de concentration en POSS. Le polyéthylène et le POSS ayant intrinsèquement tendance à cristalliser, les copolymères présentent des organisations à l'état solide complexes que nous avons caractérisés par l'utilisation combinée de la calorimétrie différentielle à balayage (DSC), de la diffraction des rayons X aux grands angles (DRX) et de la résonance magnétique nucléaire en phase solide (RMN). Dans un second volet de cette étude, nous nous sommes intéressés à la dynamique des chaînes de polyéthylène en phase amorphe et à l'évolution de celle-ci avec le taux de charge des nanocomposites. Enfin, nous avons également étudié, de façon sélective, la dynamique des segments de chaînes de polyéthylène situés au voisinage de la charge

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BARBOSA, Renata. "Estudo da modificação de argilas bentoníticas para aplicação em nanocompósitos de polietileno." Universidade Federal de Campina Grande, 2009. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1818.

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Made available in DSpace on 2018-09-26T15:00:31Z (GMT). No. of bitstreams: 1 RENATA BARBOSA - TESE (PPGEP) 2009.pdf: 13292645 bytes, checksum: e1d1eb846f17881cd108a8bad8f924ec (MD5) Previous issue date: 2009-06-19
Nanocompósitos de PEAD/argila bentonítica modificada e sem modificação foram preparados por meio do processo de intercalação por fusão. Realizou-se, previamente um estudo sistemático com quatro sais quaternários de amônio e em três tipos de argilas bentoníticas. Em seguida, fez-se a escolha de um sal quaternário de amônio e de uma argila bentonítica para dar continuidade ao trabalho. A argila escolhida foi organofilizada usando-se diferentes percentuais de sal quaternário de amônio 100%, 125% e 150% baseados na capacidade de troca de cátions (CTC) da argila. Ficou evidente por difração de raios- X (DRX) que os sais foram incorporados à estrutura da argila confirmando assim sua organofilização. Em princípio, todos os sais poderão ser usados para a organofilização da argila e, consequentemente nos sistemas de nanocompósitos PEAD/argila organofílica. Porém, foi verificado que o tipo de ânion presente pode influenciar a estabilidade térmica do sal quaternário de amônio. Os nanocompósitos foram preparados em uma extrusora de rosca dupla contrarrotacional e, em seguida, corpos de prova foram moldados por injeção. Para a avaliação da inflamabilidade dos sistemas foi utilizado o teste de queima na posição horizontal segundo a norma (UL-94HB) e o método do Calorímetro de Cone. O comportamento térmico dos nanocompósitos foi avaliado por temperatura de deflexão térmica (HDT) e termogravimetria (TG). As técnicas de DRX e microscopia eletrônica de transmissão (MET) foram utilizadas para caracterizar a morfologia e analisar o grau de expansão das argilas preparadas bem como o grau de esfoliação dos nanocompósitos. As propriedades mecânicas de tração e impacto também foram analisadas. Para efeito de comparação, determinadas composições foram extrudadas utilizando-se duas configurações de roscas da extrusora ZSK-30 corrotacional, com objetivos de variar as condições de processo e melhorar as propriedades dos nanocompósitos obtidos. Observou-se que o percentual de sal de amônio e o tipo de compatibilizante polar influenciam nas propriedades finais dos nanocompósitos.
High Density Polyethylene (HDPE) nanocomposites containing unmodified and modified bentonite clay were prepared by melt intercalation technique. Initially, four quaternary ammonium salts and three types of bentonitic clays were studied. Afterwards, one type of salt and one type of clay were chosen for the study. The clay was organophilized using 100,125 and 150wt% of quaternary ammonium salt based on cationic exchange capacity (CEC) of the clay. It was evident from the X-ray diffraction (XRD) that the salts were incorporated into the clay structure confirming its organophilization. In general, all salts may be used for clay organophilization and hence, on HDPE/Organophilic clay nanocomposites. However, it was verified that the type of anion present may influence the thermal stability of the quaternary ammonium salt. The nanocomposites were prepared in a counter-rotating twin screw extruder and the samples were prepared by injection molding. For the evaluation of the flammability, horizontal burn (UL-94HB) and cone calorimeter methods were used. The thermal behavior of the nanocomposites was analyzed by Heat Distortion Temperature (HDT) and Thermogravimetry (TG). XRD and Transmission Electron Microscopy (MET) techniques were used to characterize the morphology and analyze the degree of expansion of the prepared clays, and also the degree of exfoliation of the nanocomposites. Mechanical properties (Tensile and Impact strength) were also analyzed. Some compositions were extruded using two screw configurations of ZSK-30 co-rotacional extruder with the aim of improving the properties of the nanocomposites obtained by varying the processing conditions. It was observed that the percentage of the ammonium salt and the type of polar compatibilizer influence the final properties of the nanocomposites.

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Edakkara, A. J., J. J. Mathen, J. Sebastian, G. Ramalingam, and G. P. Joseph. "Electrical Behaviour of Polyethylene Vinyl Acetate / ZnO Nanocomposite." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35634.

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Recently, nanoscale materials have attracted material scientists because of their unique size depend-ent magnetic, optical, electrical and thermal properties. Homogeneous dispersion of nanoparticles in the polymer matrix and control of their size are vital to achieve many of these properties. In the present work, Zinc Oxide (ZnO) nanoparticles were prepared by solvothermal route. Chemical replacement reaction was chosen for the homogeneous dispersion of prepared ZnO nanoparticles into polymer matrix. Zinc oxide is an inorganic material with a large direct band gap (3.34 eV), high exciton binding energy (60 meV) and having a unique combination of properties. In inorganic/polymetric composite, the semiconducting nanoclusters enhances the electrical and thermal properties. The dielectric properties of the composites were studied using HIOKI 3532-50 LCR Hitester. The dielectric constant was found to increase with in-creasing the concentration of nano filler. DC electrical conductivity as a function of temperature was stud-ied using Keithley picoammeter 6485. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35634

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Mathen, J. J., A. J. Augustine, J. Sebastian, J. Madhavan, and G. P. Joseph. "Synthesis and Characterization of Polyethylene Vinyl Acetate / ZnSe Nanocomposite." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35635.

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In the not too distant past, polymer scientists and technologists expanded their horizons from consum-er products to the high technology arena, particularly notable in opto - electronic applications. Ethylene Vinyl Acetates (EVA) are popular because of their superior adhesion to most substrates as well as their ease of formulation. Its High transparency is a key attribute for photovoltaic cell encapsulation. It is ex-pected that with the addition of ZnSe nano fillers, EVA becomes a high refractive index polymer (HRIP) with refractive index 2.5 and posses anti-reflective property. In this work, ZnSe nanoparticles were syn-thesised by solvo-thermal method. Nano – Composite matrices based on polyethylene vinyl acetate / ZnSe were prepared by chemical replacement mechanism. Refractive index of prepared polymer nanocomposites were calculated from dielectric study using Hioki 3532-50 LCR HITESTER at various frequencies and temperatures. The presence of nano filler enhanced the refractive index and it varied with frequency and temperature. UV-Vis-NIR Spectra of the samples enable to determine the bandgap and was found to de-crease with increasing the concentration of nano fillers dispersed in polymer matrix. I-V characteristics of the nanocomposites were plotted at various concentrations of nano fillers and at various temperatures. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35635

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Fang, Liming. "Processing of UHMWPE and HA/UHMWPE nanocomposite for biomedical applications /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?MECH%202006%20FANG.

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Ucar, Egemen. "Ternary Nanocomposites Of High Density, Linear Low Density And Low Density Polyethylenes." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608446/index.pdf.

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In this study, the effects of organoclay loading, compatibilizer loading and polyethylene type on the morphology, rheology, thermal properties and mechanical properties of polyethylene/compatibilizer/organoclay nanocomposites were investigated. As compatibilizer, terpolymer of ethylene-methacrylate-glycidyl methacrylate (Lotader®
AX8900), as organoclay Cloisite®
15A were used. All samples were prepared by a co-rotating twin screw extruder, followed by injection molding. Considering ternary nanocomposites, highest impact strength results were obtained with 10% compatibilizer plus 2% organoclay
highest yield stress, elastic modulus, flexural strength, flexural modulus were obtained with 5% compatibilizer plus 4-6% organoclay. DSC data indicated that addition of organoclay and compatibilizer did not change the melting point remarkably
on the other hand it affected the crystallinity. The organoclay used had no nucleation effect on polyethylene, and the compatibilizer decreased the crystallinity of the matrix. X-ray diffraction showed that in all ternary nanocomposites and in binary nanocomposite of high density polyethylene with organoclay, layer separation associated with intercalation of the clay structure occurred,. The highest increase of interlayer gallery spacing was obtained with 10% compatibilizer plus 2% organoclay, which were 25%, 28% and 27% for HDPE, LLDPE and LDPE matrices respectively.

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Dissertations / Theses on the topic 'Polyethylene nanocomposites'

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