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1
Shah, Apoorva P. "Moisture diffusion through vinyl ester/clay nanocomposites." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2189.
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Thesis (M.S.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains xii, 147 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 97-100).
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Laot, Christelle Marie III. "Spectroscopic Characterization of Molecular Interdiffusion at a Poly(Vinyl Pyrrolidone) / Vinyl Ester Interface." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/36944.
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Mechanical properties of (woven carbon fiber / vinyl ester matrix) composites can be greatly improved if the interphase between the reinforcing high-strength low-weight fiber and the thermoset resin is made more compliant. In order to improve the adhesion of the vinyl ester matrix to the carbon fiber, a thermoplastic coating such as poly(vinyl pyrrolidone) (PVP) can be used as an intermediate between the matrix and the fiber. The extent of mutual diffusion at the (sizing material / polymer matrix) interphase plays a critical role in determining the mechanical properties of the composite.
In this research, the molecular interdiffusion across a poly(vinyl pyrrolidone))/vinyl ester monomer (PVP/VE) interface is being investigated by Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) spectroscopy. The ATR method which can be used to characterize the transport phenomena, offers several advantages, such as the ability to monitor the diffusion in situ or to observe chemical reactions. In order to separate the effects of the vinyl ester monomer diffusion and the crosslinking reaction, ATR experiments were carried out at temperatures below the normal curing temperature. Diffusion coefficients were determined by following variations in infrared bands as a function of time, and fitting this data to a Fickian model. The values of the diffusion coefficients calculated were consistent with values found in the literature for diffusion of small molecules in polymers. The dependence of diffusion coefficients on temperature followed the Arrhenius equation. Hydrogen bonding interactions were also characterized. The diffusion model used in this study, however, does not seem to be appropriate for the particular (PVP/VE) system. Because the glass transition temperature of the PVP changed as diffusion proceeded, one would expect that the mutual diffusion coefficient did not stay constant. In fact, it was shown that the Tg can drop by 140oC during the diffusion process. A more suitable model of the (PVP/VE) system should take into account plasticization, hydrogen bonding, and especially a concentration dependent diffusion coefficient. Further analysis is therefore needed.
Master of Science
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Li, Hui III. "Synthesis, Characterization and Properties of Vinyl Ester Matrix Resins." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30521.
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Vinyl ester oligomers diluted with styrene are important matrix resins for thermosetting polymer composites. A major objective of this work has been to study the chemistry and kinetics of the cure reactions of vinyl ester resins at elevated curing temperatures, which are consistent with typical composite processing conditions. The crosslinking reaction of vinyl ester resins was studied by FTIR and the loss of the carbon-carbon double bonds of the methacrylate (943 cm-1) and styrene (910 cm-1) were followed independently. A small background absorbance overlapping the absorbance at 943 cm-1 was subtracted from all spectra collected as a function of reaction time to quantify conversions. Copolymerization reactivity ratios of styrene and terminal methacrylates on vinyl ester oligomers were calculated to be rs = 0.36 ± 0.05 and rm = 0.24 ± 0.1 from early conversion data obtained at 140°C on a series of resins with systematically increasing levels of styrene. The composition data were analyzed using the integrated form of the copolymerization equation and assuming a terminal reactivity model to predict copolymer compositions throughout the reactions. These curves agreed well with the experimental data even at high conversion levels.
Another important part of this research was to study structure-property relationships of vinyl ester resins. Characteristics of vinyl ester resins and networks such as shrinkage, viscosity, crosslink density, glass transition temperature, gel swelling, and toughness have been studied. The shrinkage of vinyl ester resins during cure was calculated according to density measurements to be 4% - 10% depending on styrene content. It was found that the chain length of vinyl ester oligomers strongly affects the properties of the networks. For vinyl ester resins with longer lengths (Mn = 1000 g/mol), crosslinked networks have higher fracture toughness values and lower Tg's.
Finally, the synthesis, cure reactions and toughness of a new low viscosity vinyl ester resin were also investigated in this work. The new oligomer has a structure with which the hydroxyl groups on the backbone are replaced by methyl groups. They could be processed without a diluent. The cure reactions of the new resin were studied by FTIR, DSC and 13C-NMR.Ph. D.
4
Nguyen, Nhan Thi Thanh. "Study on effects of submicron glass fiber modification on mechanical properties of vinyl ester resin and short carbon fiber reinforced vinyl ester composite." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13142992/?lang=0, 2020. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13142992/?lang=0.
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This research investigated effect of submicron glass fiber modification on mechanical performance of short carbon fiber reinforced vinyl ester resin. Firstly, the mixture of resin and glass fiber was made by mixing submicron fiber into resin in a homogenizer at the speed of 5000 rpm in 30 minutes. Then, this modified resin was reinforced by short carbon fiber at the length of 1 mm, 3mm and 25 mm. The modifying effects were accessed by evaluating mechanical properties such as: bending, tensile, impact test as well as dynamic mechanical analysis. To explain some manners of material caused by adding glass fiber into resin, some techniques were also used (IFSS, SEM, laser microscope scanner, ultrasonic S-scan, X-ray ...).博士(工学)
Doctor of Philosophy in Engineering
同志社大学
Doshisha University
5
Burts, Ellen. "Structure and Properties Of dimethacrylate-Styrene Resins and Networks." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/29507.
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One of the major classes of polymer matrix resins under consideration for structural composite applications in the infrastructure and construction industries is the dimethacrylate matrix resin. An investigation of the relationships between the chemical structures and properties of these dimethacrylate/styrene networks has been conducted. Oligomer number average molecular weights of the polyhydroxyether ranging from 700 to 1200g/mole were studied with systematically varied styrene concentrations to assess the effects of crosslink density and chemical composition on glass transition temperatures, toughness, tensile properties and matrix strain. Network densities have been estimated from measurements of the rubbery moduli at Tg + 40°C. Within this rather small range in vinyl ester molecular weight, toughness of the resultant networks improved tremendously as the vinyl ester oligomer Mn was increased from 700g/mole to 1200g/mole due to improvements in the resistance to crack propagation. As styrene concentration was increased along all series' of materials, brittleness increased even though the molecular weight between crosslinks increased. This was attributed to the inherent relative brittleness of the polystyrene chemical structure relative to the polyhydroxyether component. This may also be related to the reactivity ratios dictating styrene and vinyl ester sequence length and warrants further investigation. As expected, the volume contraction upon cure also decreased significantly as styrene was decreased, and thus residual cure stresses may be reduced in fiber-reinforced composites. Vickers microhardness values decreased for each of the series when molecular weight increased and styrene content decreased.
Two different cure procedures were compared to assess the effects of conversion on the physical and mechanical properties. All mechanical properties investigated (i.e. fracture toughness, tensile strength, and microhardness) were dependent on the cure procedure. Materials cured at 140°C were harder, more brittle, had lower elongations and higher rubbery moduli than those cured at 25°C followed by a 93°C postcure. A maximum in the degree of conversion occurred with increasing polymerization temperature and can be explained by the competition between the chemical reaction and molecular mobility. The overall shrinkage per moles of vinyl groups converted was the same when the materials were cured at 25°C or 140°C. However, in the room temperature cured samples, there was essentially no further densification of the network during postcure, regardless of the postcure temperature. A mono-methacrylate analogue of the dimethacrylate terminated poly(hydroxyether) oligomer was synthesized and copolymerized with styrene to study the effects of chain transfer during elevated temperature reactions.Ph. D.
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Roberts, Karen Narelle 1972. "An investigation of core-shell rubber modified vinyl ester resins." Monash University, School of Physics and Materials Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/8416.
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Fernie, R. "Loading rate effects on the energy absorption of lightweight tubular crash structures." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272800.
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Robinette, Eric Jason Palmese Giuseppe R. "Toughening vinyl ester matrix composites by tailoring nanoscale and mesoscale interfaces /." Philadelphia, Pa. : Drexel University, 2005. http://hdl.handle.net/1860/1125.
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Sugimura, Kazuki. "Comparative Studies on Miscibility and Intermolecular Interaction for Cellulose Ester Blends with Vinyl Copolymers." Kyoto University, 2015. http://hdl.handle.net/2433/200460.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19197号
農博第2136号
新制||農||1034(附属図書館)
学位論文||H27||N4943(農学部図書室)
32189
京都大学大学院農学研究科森林科学専攻
(主査)教授 西尾 嘉之, 教授 木村 恒久, 教授 髙野 俊幸
学位規則第4条第1項該当
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Grishchuk, S., and J. Karger-Kocsis. "Hybrid thermosets from vinyl ester resin and acrylated epoxidized soybean oil (AESO)." eXPRESS Polymer Letters, 2010. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000441.
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Abstract. A series of hybrids composed of styrene crosslinkable vinyl ester (VE) and acrylated epoxidized soybean oil
(AESO) were produced via free radical-induced crosslinking. The VE/AESO ratio was changed between 75/25 and 25/75 wt%. Moreover, to support phase grafting the VE/AESO = 50/50 wt% hybrid was modified with phthalic anhydride in various amounts (1, 5 and 10 wt%). The structure of the hybrid systems was investigated by dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), and atomic force microscopy (AFM). The properties of the systems were assessed by static flexural and fracture mechanical tests. The resistance to thermal degradation was inspected by
thermogravimetric analysis (TGA). The results suggested that the hybrids have an interpenetrating network (IPN) structure.
With increasing AESO content the stiffness (modulus), strength and glass transition temperature (Tg) of the hybrids
decreased, whereas their ductility increased. Phthalic anhydride caused an adverse trend. Both the fracture toughness and fracture energy increased with increasing AESO content. They were less affected by adding phthalic anhydride phase couplant.
Interestingly, the hybrids outperformed the parent VE and AESO in respect to resistance to thermal degradation.
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Al, Mansour Fahad Abdulaziz M. "Interlaminar fracture toughness behaviour of flax/basalt reinforced vinyl ester hybrid composites." Thesis, University of Portsmouth, 2018. https://researchportal.port.ac.uk/portal/en/theses/interlaminar-fracture-toughness-behaviour-of-flaxbasalt-reinforced-vinyl-ester-hybrid-composites(f3f3afc8-cbb6-4fe5-a277-d86c8d37b81d).html.
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Natural fibre reinforced composites have been extensively used in non-structural components, mainly in automotive industry. For these composites to be used in structural applications, an understanding of fracture toughness behaviour is important. In this study, the influence of water absorption and hybridisation of flax and flax/basalt hybrid laminates are presented with the aim to investigating the Mode I and Mode II interlaminar fracture toughness characteristics. Four types of composite laminates namely, neat vinyl ester (neat VE), flax fibre reinforced vinyl ester (FVE), flax fibre hybridised basalt unstitched (FBVEu) and flax hybridised basalt stitched (FBVEs), were fabricated by vacuum assisted resin infusion technique. Double cantilever beam (DCB) and Three-point-end-notched flexure (3ENF) tests were performed to evaluate the critical strain energy release rates, GIC and GIIC (initiation and propagation) as well as the crack length (R-curve) in dry and wet conditions by using different data reduction methods. The morphology of delamination and the fracture shear failure of composite laminates were evaluated using scanning electron microscopy (SEM) and X-ray micro computed tomography (μCT). From the experimental results, it was found that the Mode I fracture toughness initiation GIIC init. and propagation GIIC prop. of water immersed FVE composites were decreased by an average of 27% and 10% respectively, compared to the dry specimens, whereas the fracture toughness propagation of water immersed FBVEu and FBVEs composites were increased by approximately 15% and 17% compared to dry specimens. The results of Mode II fracture toughness obtained experimentally exhibited that the fracture energy of FBVEu composites, GIIC init. and GIIC prop. were improved by 58% and 21%, respectively compared to that of FVE dry specimens. Moisture absorption behaviour caused an increase in the ductility of matrix which resultantly improved the resistance to crack initiation. However, there was a reduction in the fibre/matrix interfacial strength of FBVEu wet composites and a deterioration in the delamination resistance to crack propagation. The critical strain energy release rate of neat VE increased about 52% with reinforcement of flax fibre composites. The fracture mechanisms showed energy dissipation through matrix deformation, fibre pull-out, fibre debonding, and fibre breakage. The experimental results confirmed that basalt fibre hybridisation enhanced the durability and water repellence behaviour of flax fibre reinforced composites. Finally, this thesis provides a unique manufacturing technique to improve the interlaminar fracture toughness of flax fibre and flax/basalt hybrid composite laminates to be used in load bearing applications as an alternative to E-glass fibre reinforced composites. The outcomes of this study will be beneficial to automotive, marine and construction industries. In addition, the findings of this study will be useful for academic and researchers who are involved in the research and development of sustainable composites for light-weight structural applications.
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Phifer, Stephan Paul. "Quasi-Static and Fatigue Evaluation of Pultruded Vinyl Ester/E-Glass Composites." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/31093.
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The quasi-static strength, stiffness, and fatigue properties of cross-ply, angle-ply, and quasi-isotropic vinyl ester/E-glass non-woven tricot stitched fabric composite laminates fabricated from the Continuous Resin Transfer Molding (CRTM) pultrusion process were the focus of this research. The tricot stitch and the 6% vinyl ester matrix cure shrinkage were found to play key roles in the quasi-static and fatigue strength and stiffness properties of these laminates. Laminates tested transverse to the pultrusion axis had greater fiber undulation and maximum of 44% quasi-static strength reduction and 8% stiffness reduction compared with axially tested specimens. While the matrix failure strain was 1.9%, failure strain of these laminates range over 1.91 to 2.08% when tested along the pultrusion axis and as low as 1.29% transverse to the pultrusion axis. Fatigue evaluation, in load control mode, evaluated laminate S-N, stiffness reduction, and residual strength. Measured S-N curves and residual strength curves compared with literature were found most like woven fabric laminates, well below aerospace grade laminates. Residual strength and life analysis using Reifsnider's methodology [43], revealed that the choice of quasi-static strength and stiffness, S-N curve, laminate stiffness reduction, and residual strength shape parameter, J, strongly affect predicted life. Predictions at high fatigue stress/low cycle were more exact than at low stress; the S-N curve was steep initially but at low stress/high cycle was nearly horizontal. The best predictions utilized separate off-axis stiffness reductions of E2 obtained from cross-ply and G12 from angle-ply laminates, the quasi-static strength and stiffness of the laminate predicted, and the average S-N and residual strength curves.Master of Science
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Li, Yena. "Processing Nano Graphene Plates (NGPs) and NGP Nanocomposite." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1176430617.
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El-Chiti, Fadi. "Experimental Variability of E-Glass Reinforced Vinyl Ester Composites Fabricated by VARTM/Scrimp." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/El-ChitiF2005.pdf.
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Michelis, Alexandros. "Plug repairs of marine glass fiber / vinyl ester laminates subjected to uniaxial tension." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50555.
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Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references (leaves 57-61).
Glass fiber/vinyl ester composite laminates are currently being used and proposed for the hulls, bulkheads, and superstructures of large ships. This thesis examines the effectiveness of the repair of such laminates using glass fiber/vinyl ester chopped strand mat plugs to fill circular holes. The stress distributions around circular holes in various glass fiber/vinyl ester woven roving laminates subjected to uniaxial tension are calculated before and after repairs using plug materials of different fiber volume fractions. The orthotropic laminates ranged from balanced to unidirectional woven rovings, and the chopped strand mat plug fiber volume fractions ranged from 0 to 0.40. The effectiveness of the plug in reducing the laminate stresses increased monotonically with increasing fiber volume fraction, reducing the maximum laminate stress to about 60% of the unrepaired laminate stress at a plug fiber volume fraction of 0.40.
by Alexandros Michelis.
Nav.E.and S.M.
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Huo, Shanshan. "The Physico-Chemical Investigation of Interfacial Properties in Natural Fiber/Vinyl Ester Biocomposites." Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26827.
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Bast fibers are one of most widely used types of cellulosic natural fibers. Flax fibers, a specific type of bast fiber, have historically been used as reinforcements in composites because they offer competitive advantages, including environmental and economic benefits, over mineral-based reinforcing materials. However, the poor interfacial properties due to the hydrophilicity of flax fibers and the hydrophobicity of most polymer matrices reduce the mechanical performance of flax thermoset composites. On the other hand, the structure of flax fiber is more complex than synthetic fibers, which causes most of traditional mechanical tests from the transverse direction to evaluate the interfacial properties of flax composites are not valid. In this study, the physical and chemical properties of flax fibers, vinyl ester resin and their composites are investigated. A comprehensive understanding of flax fiber, vinyl ester systems and their composites has been established. Surface modifications to the flax fiber and chemical manipulations on vinyl ester systems have been studied to improve the interfacial properties of flax/vinyl ester biocomposites. A new chemical manipulation method for vinyl ester system has been invented. The specific interlaminar shear strength of alkaline treated flax/VE with 1.5% AR shows approximately 149% increase than untreated flax/VE composites. NaOH/Ethanol treated flax/VE with AR shows 33% higher in specific flexural modulus and 73% better in specific flexural strength than untreated flax/VE composites. In addition, AR modified alkaline treated flax composites performs approximately 75% better in specific tensile modulus and 201% higher in specific tensile strength than untreated flax/VE composites. Flax/VE composite with high elastic modulus, which is higher than their theoretically predicted elastic modulus, was achieved. The effects of thermal properties of flax fibers and vinyl ester resin systems on the interfacial properties of their biocomposites were also studied. The theory of modifying the thermal properties of flax and vinyl ester to improve the interfacial adhesion has been proved by the study of the thermal residual stresses in their composites by XRD techniques.
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Alateyah, Abdulrahman Ibrahim S. "Characterisations and properties of nanocomposites based upon vinyl ester matrix and layered silicate." Thesis, University of Portsmouth, 2014. https://researchportal.port.ac.uk/portal/en/theses/characterisations-and-properties-of-nanocomposites-based-upon-vinyl-ester-matrix-and-layered-silicate(284a9725-a8b1-4d34-9f30-64926735cd1b).html.
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In this research, various concentrations of layered silicate based on vinyl ester nanocomposites were prepared and the effect of the incorporation of layered silicate into the polymer matrix on the different properties was investigated. The characterisations of interlaminar structure of the nanocomposites by X-ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Spectrometry and Transmission Electron Microscopy are undertaken. This study revealed that the incorporation of layered silicate into the polymer matrix formed uniformly distributed nanocomposites structure at low clay content (i.e. 1, 2, and 3 wt.%). At 4 wt.% clay loading, the partially intercalated / exfoliated nanocomposites system was observed as proved by the different characterisations' results. However, the addition of more clay such as 5 wt.% resulted in decreasing the overall intercalation level due to the existence of aggregation layers. The addition of layered silicate into the vinyl ester matrix increased the environmental, mechanical and thermal properties, and the enhancements were correlated to the results of the characterisations' outputs. The mechanical properties such as flexural, tensile, nanoindentation, impact, and creep properties of neat samples were improved by the incorporation of layered silicate. The presence of layered silicate into the polymer matrix increased the tensile strength and modulus and flexural strength and modulus up to 4 wt.% clay content. The level of intercalation of nanocomposites played an important role in the improvements of the mechanical properties. So, the tensile and flexural properties were correlated to the characterisations' results. At 5 wt.% clay content, the modulus and strength of both tensile and flexural were reduced due to the effect of aggregation layers where the interfacial interaction between the layered silicate and the polymer is reduced. The nanoindentation test showed that the addition of layered silicate increased the reduced modulus and hardness of the nanocomposites compared to the neat vinyl ester. The presence of only 1 wt.% clay loading increased the hardness and reduced modulus at up to 13% and 11% respectively compared to the pristine polymer. The improvement percentage of hardness and modulus at 2 wt.% were 31% and 19% respectively. The ultimate improvements were observed at 4 wt.% clay loading, where the enhancements in hardness and modulus were 56 and 50% respectively compared to the neat vinyl ester. Further addition of clay resulted in marginal reductions in these properties. The impact properties of the neat vinyl ester and the nanocomposites were investigated using a low velocity impact testing. The addition of layered silicate into the polymer matrix showed that an optimum range of nanoclay reinforcement in the vinyl ester matrix can produce enhanced load bearing and energy absorption capability compared to the neat matrix. Likewise, the influence of the clay addition into the neat polymer on the creep relaxation behaviour at 25°C and 60°C was studied. In both cases, the presence of the layered silicate remarkably improved the creep behaviour. The strain reduction is related to the clay concentration level. The neat polymer illustrated higher strain compared to the nanocomposites samples. Moreover, the addition of layered silicate into the polymer matrix improved the thermal properties. Thermal Gravimetric Analysis (TGA) showed that the nanocomposites represent better stability compared to the neat polymer. The onset temperature of the nanocomposites was higher than the neat polymer. At 1, 2, 3, and 4, wt.% clay content, the improvements in onset temperature were 7 %, 4.2 %, 4 %, 2.5 % respectively compared to the virgin polymer. In addition, the incorporation of layered silicate into the polymer matrix increased the thermal conductivity. At 4 wt.% clay, the thermal conductivity was increased by 12% compared to the neat polymer. Differential Scanning Calorimetry (DSC) is also performed in order to study the effect of the addition of layered silicate into the polymer on the glass transition temperature. The level of intercalation is critical to the Tg values. The nanocomposites represented a marginal reduction in Tg, however at 4 wt.% clay loading the Tg was as same as the neat polymer which was traced to the well-dispersed structure. Furthermore, the study of environmental measurements, which included the water absorption behaviour and its effect on the nanoindentation test, was investigated. The improvement of the water repellence behaviour was observed for the nanocomposites. The enhancements in barrier properties were related to the clay content. At 5 wt.% clay loading, the reduction of water uptake was about 1266% compared to the neat polymer. The hardness and elastic moduli after water absorption was reduced due to the effect of water molecules entering into the polymer chains. However, the higher amount of clay reinforcement led to less reduction in hardness due to the formation of the barrier properties by the layered silicate. The hardness of neat polymer after immersing in water was reduced by 30% whereas the hardness of 5 wt.% nanocomposites showed only a reduction by 10.3% compared to the dry sample.
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Davey, Scott W. "A foundational investigation of vinyl ester / cenosphere composite materials for civil and structural engineering." University of Southern Queensland, Faculty of Engineering and Surveying, 2004. http://eprints.usq.edu.au/archive/00003180/.
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[Abstract]: With the increasing use of fibre reinforced polymer (FRP) composites in civil engineering structures, there is a growing realisation of the need to develop newstructural systems which can utilise the unique characteristics of these materials in a more efficient and economical manner. In many instances this will require thedevelopment of new materials tailored to address the unique performance and economic parameters of mainstream construction. Over recent years, researchers at the University of Southern Queensland have pioneeredthe use of a new type of particulate filled polymer core material which greatly improves the robustness and cost effectiveness of FRP structural systems. These compositematerials are composed of small hollow spherical fillers (microspheres) in a thermosetting polymer matrix. Initial research into these materials, including theirfeasibility in prototype structural elements, have shown these materials to have major potential for widespread application in structural composite systems.One of the most promising classes of these materials investigated to date are vinyl ester / cenosphere composites, which utilise cenospheres derived from fly ash in a vinyl ester matrix. Previously reported studies into these materials have been restricted to initialsurveys of material behaviour which sought to identify key parameters in achieving desired performance outcomes in the composite. This dissertation presents the first in-depth investigation of these materials specifically as a core material option for civil infrastructure applications. The particular focus of this work is on the relationship of the vinyl ester matrix to the characteristics of the resultingcomposite. Several key matrix parameters were identified and assessed as to their influence on cure characteristics, fabrication operations, mechanical properties and theretention of such properties under elevated service temperatures. The outcomes of this work have significantly improved the understanding of matrix influences on the behaviour of these composite systems and have been drawn together to provide a number of recommendations on the application of this new technology to new structural systems.
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Stevanovic, Dejan, and dejan@mso anu edu au. "Delamination Properties of a Vinyl-Ester/Glass Fibre Composite Toughened by Particulate-Modified Interlayers." The Australian National University. Faculty of Engineering and Information Technology, 2002. http://thesis.anu.edu.au./public/adt-ANU20030421.212730.
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The main aim of this work is to examine fracture toughness improvement mechanisms of a
composite material containing tough interlayers modified with large thermoplastic
particles.
¶
Various vinyl-ester (VE)/ poly(acrylonitrile-butadiene-styrene) (ABS) blends were used
for the interlayer-toughening of a VE/glass fibre composite to increase delamination
resistance of the material under mode I and mode II loading. Dry ABS powder was mixed
with the liquid resin in four different weight ratios: 3.5, 7, 11 and 15 phr (parts per
hundred parts of resin) while the layer thickness was varied from 150 to 500um.
Firstly, the tensile and mode I fracture toughness properties of the VE/ABS blends were
assessed, and, by using the Raman Spectroscopy technique, a chemical reaction was
discovered which occurred during ABS/VE mixing. This reaction consisted of butadiene
dissolution from the ABS particles into the VE. Also, butadiene saturation within the VE
was achieved at a composition of around 7% ABS particle content. Both mode I and mode II
fracture toughness of the composite were significantly improved with the application of
interlayers. Mode I fracture toughness GIc was found to be a function of
interlayer thickness and ABS particle content variations, with the latter dominating
GIc after the saturation point. Mode II fracture toughness was found to be
independent of interlayer thickness and only moderately influenced by particle content.
The toughening mechanisms that were the most influential within this interlayered
material were plastic deformation and micro-cracking of the layer materials. Evidence of
both mechanisms was found using optical and scanning electron microscopy (SEM).
¶
A numerical analysis was conducted, using the experimental results from this study, to
further explain the basic toughening mechanisms and fracture behaviour in the materials.
The aim of the analysis was to examine the influence of the particles on the plastic zone
size that develops in front of the crack tip, and the interaction between the particles
and the crack tip. For this purpose FEA elastic-plastic crack propagation models were
employed. Good agreement with the experimental data was found.
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Stevanović, Dejan. "Delamination properties of a vinyl-ester/glass fibre composite toughened by particle-modified interlayers /." View thesis entry in Australian Digital Theses Program, 2001. http://thesis.anu.edu.au/public/adt-ANU20030421.212730/index.html.
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Garland, Chrystal A. "Effect of manufacturing process conditions on the durability of pultruded vinyl ester/glass composites." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1774.
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Thesis (M.S.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains x, 125 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 83-86).
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BUARQUE, EGBERT NASCIMENTO. "CILINDRICAL DEFECTS INFLUENCE ON THE TENSILE STRENGTH OF FIBERGLASS REINFORCED VINYL ESTER COMPOSITE RINGS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5929@1.
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Em Influência de defeitos cilíndricos sobre o limite de
resistência de anéis de resina éster vinílica reforçada com
fibras de vidro é realizado um estudo da influência de
defeitos sobre a resistência mecânica de um tubo compósito
de resina vinil éster reforçada com fibras de vidro picadas
e contínuas. Os defeitos, com geometria cilíndrica, são
artificialmente fabricados e têm suas dimensões (raio e
profundidade) variados. A resistência mecânica do material
foi avaliada através do ensaio de tração de anéis previsto
na norma ASTM D 2290. Os resultados são analisados pelo
método da ANOVA, obtendo-se, assim, a significância das
variáveis relacionadas ao defeito (raio e profundidade).
Realiza-se também a modelagem por elementos finitos do
ensaio de tração, a fim de se avaliar o comportamento
mecânico do material durante o ensaio.Cilindrical defects influence on the tensile strength of fiberglass reinforced vinyl ester composite rings investigates the influence of defects on the mechanical strength of a fiberglass reinforced vinylester composite pipe. The defects are manufactured in cilindrical shape with dimensions (radius and depth) varying over a selected range. The samples are tested in accordance with the ASTM D 2290 standard and the results are analyzed by the ANOVA method. A finite element model of the test is made in order to investigate the mechanical behaviour of the material during testing.
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Hu, Fang Zong. "Fatigue of glass reinforced plastic pipes and joints for offshore applications." Thesis, University of Newcastle Upon Tyne, 1997. http://hdl.handle.net/10443/678.
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In this thesis the static and fatigue characteristics of glass filament wound plastic pipes and joints are examined by experiments and numerical analysis. A hydraulic fatigue test rig, capable of exerting static or cyclic pressures of up to 70 MPa, was designed and built to enable pressure tests to be carried out on glass reinforced epoxy and glass reinforced vinyl ester composite pipes incorporating various joints. Static weepage and burst tests were performed on tubular specimens with and without rubber liners to determine their weepage and burst strengths under internal hydraulic pressure and to investigate the influence of the joints. Fatigue weepage tests were performed to determine the fatigue life and failure modes of glass fibre/epoxy and glass fibre/vinyl ester pipes and joints. For each material system, three types of specimen were tested. These were plain pipes, pipes with coupler-bonded joints (or laminate joints in the case of vinyl ester resin based pipes) and pipes with spigot/socket bonded joints. All specimens were commercial products with nominal diameters of two inches (50 mm). A family of curves showing pressure versus life was obtained. It was observed that weepage mostly occurred close to the pipe joints when pipes were subjected to internal pressure. Optical microscopy was used to investigate the damage initiation and propagation mechanisms in the specimens after testing. Finally, two-dimensional and three-dimensional finite element analyses were carried out to calculate the stress and strain distributions, to predict the strength, to interpret the experimental results and to examine the failure modes of the specimens. Ply-by-ply stress analysis and the Tsai-Wu failure criterion were employed for the strength prediction.
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Drake, Daniel Adam. "Viscoelastic characterization of vapor-grown carbon nanofiber/vinyl ester nanocomposites using a response surface methodology." Thesis, Mississippi State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1536065.
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The effects of vapor-grown carbon nanofiber (VGCNF) weight fraction, applied stress, and temperature on the viscoelastic responses (creep strain, creep rate, and creep compliance) of VGCNF/vinyl ester (VE) nanocomposites were studied using a central composite design (CCD). The nanocomposite test articles were fabricated by high shear mixing, casting, curing, and post-curing in an open face mold under a nitrogen environment. Short-term creep/creep recovery experiments were conducted at prescribed combinations of temperatures (23.8 - 69.2 C), applied stresses (30.2 - 49.8 MPa), and VGCNF weight fractions (0.00 - 1.00 parts of VGCNF per hundred parts of resin, phr) determined from the CCD. The response surface models (RSMs) for predicting these viscoelastic responses were developed using the least squares method and an analysis of variance procedure. The response surface estimates indicate that increasing the VGCNF weight fraction marginally increases the creep resistance of the VGCNF/VE nanocomposite at low temperatures (i.e., 23.8 - 46.5 C). However, increasing the VGCNF weight fraction for temperatures greater than 50 C decreased the creep resistance of these nanocomposites. The latter response may be due to a decrease in the nanofiber-to-matrix adhesion as the temperature is increased. The RSMs for creep strain, creep rate, and creep compliance revealed the interactions between the VGCNF weight fraction, stress, and temperature on the creep behavior of thermoset polymer
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Eisenheld, Leopold. "Measuring the Adhesive Bond Quality of Vinyl Ester-Glass Composites on Novolak HMR Treated Wood." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/EisenheldL2003.pdf.
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Liu, Xuan. "Novel vinyl ester-based copolymers : RAFT/MADIX synthesis and properties in supercritical carbon dioxide media." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30092.
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Introduction Un fluide supercritique (SCF) est une substance dont la température et la pression sont à la fois au-dessus de leurs valeurs essentielles qui sont définies comme le point critique. Le point critique (Pc) désigne le point où les phases gaz, liquide et phase supercritique coexistent et il peut être observé expérimentalement par une opacité critique. Les propriétés des SCFs sont différentes de celles des liquides et des gaz ordinaires. Près de la densité critique, les SCFs affichent des propriétés qui sont dans une certaine mesure intermédiaire entre celles d'un liquide et un gaz. Parmi les fluides supercritiques, le scCO2 a certainement un excellent potentiel de développement pratique en raison de ses faibles conditions critiques (Tc = 31 °C, Pc = 74 bars), et en raison de la nature non-polaire et faible des forces de van der Waals impliquant le CO2. Les espèces hydrophiles (tels que des acides aminés, des protéines et de nombreux catalyseurs) sont souvent insolubles dans le scCO2. De toute évidence, il existe une limitation de l'application de dioxyde de carbone supercritique. Récemment, dans le but de remédier à cet inconvénient, une approche plus efficace consiste à utiliser des tensioactifs appropriés pour produire des micro-émulsions eau/CO2 ou micelles inverses. Consan et Smith ont testé la solubilité de plus de 130 agents tensioactifs disponibles dans le commerce dans le scCO2 à 50 °C et de 10 à 50 MPa. Tous sont très peu solubles ou seulement légèrement solubles dans le scCO2, de sorte qu'ils ne pouvaient pas être utilisés comme surfactants pour ce milieu. Toutefois, certains matériaux non polaires de bas poids moléculaire peuvent se dissoudre dans le scCO2, et sont utilisés avec succès pour divers procédés industriels tels que l'extraction par fluide supercritique, la chromatographie en fluide supercritique et en tant que milieu réactionnelSupercritical fluid is a substance whose temperature and pressure are both above their critical values which are defined as the critical point. Similarly to the triple point which defines the zero-variance point for the solid, gas and liquid states, the critical point (Pc) denotes the point where the gas, liquid and supercritical phases coexist and it can be experimentally observed through a critical opacity. Properties of SCFs are different from those of ordinary liquids and gases. Close to the critical density, SCFs display properties that are to some extent intermediate between those of a liquid and a gas. For example, a SCF may be relatively dense and dissolve certain solids while being miscible with permanent gases and exhibiting high diffusivity and low viscosity. In addition, SCFs are highly compressible and the density (and therefore solvent properties) can be "tuned" over a wide range by varying pressures and temperatures. Among supercritical fluids, scCO2 certainly has excellent potential for practical development not only because of its low critical conditions (Tc = 31 °C, Pc = 74 bar), but also due to some other factors such as: CO2 is non-toxic. Its threshold air concentration for working conditions is as high as 5000 ppm. By means of comparison, a daily exposition to 10 ppm of chloroform is considered hazardous. CO2 is non-flammable. This constitutes another very competitive advantage compared to halogenated solvents. Its high pressure vapour-superior to 60 bar-allows its complete removal from processed materials. Thus, CO2 is one of the two solvents fully approved by the Food and Drug Administration (FDA), along with water. CO2 has a low reactivity and is inert towards oxidation. It is also a non-transferring species for radicals. Heat and mass transfer are significantly enhanced in scCO2 due to its properties of low viscosity and densities. Its low surface tension allows wetting structured materials better than liquids usually do. However, besides the cost of high-pressure vessels, CO2 still has intrinsic physical disadvantages: A low cohesive energy density which confers a weak solvent strength to CO2. CO2 is a Lewis acid through its electron-deficient carbon. It thus reacts reversibly with strong Lewis bases such as primary and secondary amines. But this can be turned into an advantageous property for the capture of CO2 by amine-based solvents and surfactants, polymers and solvents that possess CO2-responsive moieties such as guanidines and amidines. CO2 is a poison for Ziegler-Natta and palladium-based catalysts due to the formation of CO. Due to the non-polar and weak Van der Waals forces of CO2, most lipophilic and hydrophilic species (such as amino acids, proteins and many catalysts) are often insoluble in scCO2. Obviously, it is a limitation for the application of supercritical carbon dioxide. Recently, in order to overcome this disadvantage, the most effective approach is to use suitable surfactants to produce water-in-CO2 microemulsions or reverse micelles. Consan and Smith tested the solubility of over 130 commercially available surfactants in scCO2 at 50 °C and 10-50 MPa. All of them were rarely soluble or only slightly soluble in scCO2, so they could not be employed as surfactants in scCO2
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Ravindran, Naveenkamal. "Durability of E-glass fiber reinforced vinyl ester polymer composites with nanoclay in an alkaline environment." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4209.
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Thesis (M.S.)--West Virginia University, 2005.Title from document title page. Document formatted into pages; contains vii, 54 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 51-52).
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Broyles, Norman S. "Thermoplastic Sizings: Effects on Processing, Mechanical Performance, and Interphase Formation in Pultruded Carbon Fiber/Vinyl-Ester Composites." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/30283.
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Sizings, a thin polymer coating applied to the surface of the carbon fiber before impregnation with the matrix, have been shown to affect the mechanical performance of the composite. These sizings affect the processability of the carbon fiber that translates into a composite with less fiber breakage and improved fiber/matrix adhesion. In addition, the interdiffusion of the sizing and the bulk matrix results in the formation of an interphase. This interphase can alter damage initiation and propagation that can ultimately affect composite performance. The overall objective of the work detailed in this thesis is to ascertain the effects that thermoplastic sizing agents have on composite performance and determine the phenomenological events associated with the effects.
All of the thermoplastic sizings had improved processability over the traditional G' sizing. These improvements in processability translated into a composite with less fiber damage and improved surface quality. In addition, all of the thermoplastic sizings outperformed the industrial benchmark sizing G' by at least 25% in static tensile strength, 11% in longitudinal flexure strength, and 30% in short beam shear strength. All moduli were found to be unaffected by the addition of a sizing.
The interphase formed in K-90 PVP sized carbon fiber composites was fundamentally predicted from the constitutive properties of K-90 PVP/Derakane™ interdiffusion and fundamental mass transport equations. The K-90 PVP sizing material interdiffusing with the Derakane™ matrix was found to be dissolution controlled. The dissolution diffusion coefficient had an exponential concentration dependence. Fundamental mass transport models were utilized to predict the interphase profile. The predicted K-90 PVP interphase concentration profile displayed steep gradients at the fiber/matrix interface but essentially no gradients at points distant from the fiber surface. The predicted mechanical property profile was essentially flat for the modulus but did show a steep gradient in the strain-to-failure and shrinkage properties. However, the K-90 PVP interphase compared to the unsized/pure Derakane™ interphase showed improvements in strength and strain-to-failure and a reduction in cure shrinkage without significantly affecting the interphase tensile or shear moduli.Ph. D.
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Totten, Kyle. "Determination of the tensile strength of the fiber/matrix interface for glass/epoxy & carbon/vinyl ester." Thesis, Florida Atlantic University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10096031.
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The tensile strength of the fiber/matrix interface was determined through the development of an innovative test procedure. A miniature tensile coupon with a through-thickness oriented, embedded single fiber was designed. Tensile testing was conducted in a scanning electron microscope (SEM) while the failure process could be observed. Finite element stress analysis was conducted to determine the state of stress at the fiber/matrix interface in the tensile loaded specimen, and the strength of the interface. Test specimens consisting of dry E-glass/epoxy and dry and seawater saturated carbon/vinylester 510A were prepared and tested. The load at the onset of debonding was combined with the radial stress distribution near the free surface of the specimen to reduce the interfacial tensile strength (σi). For glass/epoxy, σi was 36.7±8.8 MPa. For the dry and seawater saturated carbon/vinylester specimens the tensile strengths of the interface were 23.0±6.6 and 25.2±4.1 MPa, respectively. The difference is not significant.
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Svetlik, Stephanie Laura. "An investigation in the hygrothermal degradation of an E-glass/vinyl-ester composite in humid and immersion environments." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3316474.
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Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed September 10, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Boyd, Steven Earl. "Compression Creep Rupture of an E-glass/Vinyl Ester Composite Subjected to Combined Mechanical and Fire Loading Conditions." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/29896.
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Polymer matrix composites are seeing increasing use in structural systems (e.g. ships, bridges) and require a quantitative basis for describing their performance under combined mechanical load and fire. Although much work has been performed to characterize the flammability, fire resistance and toxicity of these composite systems, an understanding of the structural response of sandwich type structures and laminate panels under combined mechanical and thermal loads (simulating fire conditions) is still largely unavailable. Therefore a research effort to develop a model to describe the structural response of these glass/vinyl esters systems under fire loading conditions is relevant to the continuing and future application of polymer matrix composites aboard naval ships.
The main goal of the effort presented here is to develop analytical models and finite element analysis methods and tools to predict limit states such as local compression failures due to micro-buckling, residual strength and times to failure for composite laminates at temperatures in the vicinity of the glass transition where failure is controlled by viscoelastic effects. Given the importance of compression loading to a structure subject to fire exposure, the goals of this work are succinctly stated as the:(a)Characterization of the non-linear viscoelastic and viscoplastic response of the E-glass/vinyl ester composite above Tg. (b)Description of the laminate compression mechanics as a function of stress and temperature including viscoelasticity.(c)Viscoelastic stress analysis of a laminated panel ([0/+45/90/-45/0]S) using classical lamination theory (CLT).
Three manuscripts constitute this dissertation which is representative of the three steps listed above. First, a detailed characterization of the nonlinear thermoviscoelastic response of Vetrotex 324/Derakane 510A - 40 through Tg was conducted using the Time - Temperature - Stress - Superposition Principle (TTSSP) and Zapas - Crissman model. Second, the modeling approach and viscoelastic relaxation mechanism is validated by substituting the shear relaxation modulus into a compression strength model to predict lifetimes for isothermal and one sided heating of unidirectional laminates. Finally, viscoelastic stress analysis using CLT is performed for a general laminated panel to predict lifetimes under one sided heating. Results indicate that when temperatures remain in the vicinity of Tg, the laminate behavior is controlled by thermoviscoelasticity.Ph. D.
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Rosario, Astrid Christa. "The Chemistry of Dimethacrylate-Styrene Networks and Development of Flame Retardant, Halogen-Free Fiber Reinforced Vinyl Ester Composites." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/11228.
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One of the major classes of polymer matrix resins under consideration for structural composite applications in the infrastructure and construction industries is vinyl ester resin. Vinyl ester resin is comprised of low molecular weight poly(hydroxyether) oligomers with methacrylate endgroups diluted with styrene monomer. The methacrylate endgroups cure with styrene via free radical copolymerization to yield thermoset networks. The copolymerization behavior of these networks was monitored by Fourier Transform Infrared Spectroscopy (FTIR) at various cure conditions. Reactions of the carbon-carbon double bonds of the methacrylate (943 cm-1) and styrene (910 cm-1) were followed independently. Oligomers possessing number average molecular weights of 700 g/mole were studied with systematically increasing levels of styrene. The Mortimer-Tidwell reactivity ratios indicated that at low conversion more styrene was incorporated into the network at lower cure temperatures. The experimental vinyl ester-styrene network compositions deviated significantly from those predicted by the Meyer-Lowry integrated copolymer equation at higher conversion, implying that the reactivity ratios for these networks may change with conversion. The kinetic data were used to provide additional insight into the physical and mechanical properties of these materials.
In addition to establishing the copolymerization kinetics of these materials, the development of halogen free fiber reinforced vinyl ester composites exhibiting good flame properties was of interest. Flame retardant vinyl ester resins are used by many industries for applications requiring good thermal resistance. The current flame-retardant technology is dependent on brominated vinyl esters, which generate high levels of smoke and carbon monoxide. A series of halogen free binder systems has been developed and dispersed in the vinyl ester to improve flame retardance. The binder approach enables the vinyl ester resin to maintain its low temperature viscosity so that fabrication of composites via Vacuum Assisted Resin Transfer Molding (VARTM) is possible. The first binder system investigated was a polycaprolactone layered silicate nanocomposite, which was prepared via intercalative polymerization. Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) data indicated a mixed morphology of exfoliated and intercalated structures. The mechanical properties and the normalized peak heat release rates were comparable to the neat vinyl ester resin.
Alternative binder systems possessing inherent flame retardance were also investigated. A series of binders comprised of novolac, bisphenol A diphosphate, and montmorillonite clay were developed and dispersed into the vinyl ester matrix. Cone calorimetry showed reductions in the peak heat release rate comparable to the brominated resin.Ph. D.
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Saidpour, Seyed H. "The effect of fibre/matrix interfacial interactions on the mechanical properties of unidirectional E-glass reinforced vinyl ester composites." Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/7116.
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This thesis first reviews, and then evaluates, the importance of fibre/matrix interfacial bonding in determining composite properties with particular reference to unidirectional E-glass reinforced vinyl ester systems. The potential of various non-destructive evaluation (NDE) techniques for determining the correlation between fibre treatment and bulk composite properties (such as interlaminar shear strength and tensile strength etc.) are described in detail. Acoustic Emission (AE) in particular is demonstrated to be useful in studying the process of damage during the mechanical tests. Some samples are also examined by optical and scanning electron microscopy, dynamic mechanical analysis, and by a new and novel technique known as Sound Image Analysis (SIA) which allows the total spectrum of crack sound output to be analysed. Overall it has been established that the NDE techniques used can distinguish between different levels of interfacial bond strength and that AE can follow the progressive changes in fracture mode that follow from fibre surface treatment variations.
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Jungkuist, David Alan. "Simulation of Enviro-mechanical Durability for Life Prediction of E-Glass/Vinyl Ester Composites using a Bridge Service Environment." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/32791.
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In order for composites to become an accepted material for infrastructure application, life prediction and durability must be understood. The majority of studies have examined the strength and fatigue response of composites under hot and/or moist conditions. Various researchers have also studied life prediction methods for composite materials under fatigue, primarily for high performance applications. Little work has been done to study durability under combined service conditions for composites used in civil infrastructure applications.
This thesis focuses on the development of a life prediction model for use with fiber reinforced polymer composites in bridge service environments. The Tomâ s Creek Bridge of Blacksburg, VA is used as a guiding case study. First, the tensile properties of the composite were studied as a function of temperature and moisture. Damage accumulation was studied as a function of cyclic loading and temperature cycles. The enviro-mechanical conditions, including moisture, temperature and fatigue loading, were then used in a computer simulation to predict the life of a vinyl ester/glass composite under an approximate bridge service environment.
Finally, a laboratory simulation was conducted that approximates the temperature and humidity that is seen at the Tomâ s Creek Bridge, but in an accelerated time frame. A multi-stress fatigue pattern, mimicking cars and trucks passing over the bridge, was used. One year of conditions was accelerated to approximately six hours and thirty-three minutes using a servo-hydraulic test frame and environmental chamber.
The final results showed that life prediction methodology conservatively predicted the lifetime of a vinyl ester/glass composite under the enviro-mechanical conditions. The damage of the composite was predominately driven by cyclic loading. The environmental conditions of moisture and temperature had only a small affect on the lifetime of the composite. This lack of environmental sensitivity is largely due to the durability of the resin system.Master of Science
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Urrutia, Valenzuela Roberto. "Plug repairs of marine glass fiber / vinyl ester laminates subjected to in-plane shear stress or in-plane bending moment." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61923.
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Thesis (S.M. in Naval Architecture and Marine Engineering )--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, Thesis (S.M. in Mechanical Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 71-73).
Glass fiber / vinyl ester composite laminates represent an important class of modem fiber composites being proposed or used in state-of-the-art shipbuilding. This thesis examined the effectiveness of chopped strand mat (CSM) plug repairs of glass fiber / vinyl ester woven roving laminates subjected to in-plane shear and bending. An advantage of this type of repair scheme is its simplicity when compared to more traditional schemes such as scarf or step repairs. The stress concentrations around circular holes in glass fiber / vinyl ester woven roving laminates subjected to in-plane shear and bending were calculated before and after repairs using CSM plugs, also of glass fiber / vinyl ester, having varying fiber volume fractions. The laminates were orthotropic and ranged from balanced to unidirectional woven roving, and the CSM plug fiber volume fractions ranged from 0 to 0.40. For in-plane shear stress, as the plug fiber volume fraction increased from 0 to 0.40, the maximum stress concentration along the circular holes in the laminate was reduced from about 25% to 61%. For in-plane bending, as the plug fiber volume fraction increased from 0 to 0.40, the maximum stress concentration in the laminate was reduced from about 25% to 45%.
by Roberto Urrutia Valenzuela.
S.M.in Mechanical Engineering
S.M.in Naval Architecture and Marine Engineering
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Sumner, Michael Jameson. "High Performance Materials Containing Nitrile Groups." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/11261.
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The objective of the research described in this thesis has been to improve the toughness of phenolic networks while maintaining flame resistance. A four step synthetic scheme has been developed to prepare 4,4¡¦-Bis(3,4-dicyanophenoxy)biphenyl(biphenoxyphthalonitrile). A 700 g mol-1 novolac oligomer was cured with relatively low concentrations of this reagent (~20 wt %) into high Tg (~190 ¢XC) networks. The curing reaction was attrubuted to nucleophilic attack of the phenolic hydroxyl on the nitrile groups of the phthalonitrile resulting in the formation of heterocylic rings. TGA and cone calorimetry demonstrated that these networks have excellent thermo-oxidative stability.
Further goals were to develop halogen-free, flame retardant monomers for improving the thermo-oxidative resistance of polystyrene and dimethylacrlyate/styrene(vinyl ester) networks. 4-Vinylphenoxyphthalonitrile, a phthalonitrile derivative of styrene, was synthesized. FTIR has been utilized to demonstrate this new monomer co-cured into vinyl ester networks in free radical thermosetting polymerizations. Upon post-curing the networks between 200-260 ¢XC for ~1.5 h, the nitrile groups reacted to form heterocyclic crosslinks. TGA and cone calorimetry demonstrated that the 4-vinylphenoxyphthalonitrile substantially improved the flame resistance of vinyl ester networks.
Copolymerizations of styrene and 4-vinylphenoxyphthalonitrile were conducted at 75 ¢XC for 24 h using 0.5 wt % AIBN in chlorobenzene. Dynamic TGA at 10 ¢XC min-1 in air showed that copolymers containing 10 and 25 mole % of 4-vinylphenoxyphthalonitrile had increased initial weight loss temperatures in air by (~50 ¢XC higher) and increased the char yield between 400-600 ¢XC.
High molecular weight nitrile-functional, (hexafluoroisopropylidene)diphenol based aromatic poly(arylene ether)s with pendent sulfonic acid groups were prepared by nucleophilic step copolymerization of 4,4¡¦-(hexafluoroisopropylidene)diphenol, 2,6-dichlorobenzonitrile, and 3,3¡¦-disulfonate-4,4¡¦-dichlorodiphenylsulfone under basic conditions in N-methyl-2-pyrrolidinone at 200 â aC. A series of these materials with systematically varied concentrations of the sulfonic acid moieties showed increased glass transition temperatures, proton conductivities, and hydrophilicities as a function of disulfonation. Atomic force microscopy (AFM) demonstrated that the acidified copolymer with 35 mole % of disulfonated units was phase separated into a co-continuous morphology of hydrophobic and hydrophilic domains.Ph. D.
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Starr, Brian Craig. "Inter-Relationships Between Chemistry, Network Structure and Properties of Chain Growth Dimethacrylate Thermosets." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/29949.
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Dimethacrylate oligomers diluted with styrene reactive diluents (so-called vinyl ester resins) are becoming increasingly important for composites in applications such as transportation vehicles, printed wiring boards and civil infrastructure. This research has focused on the generation and comparative analysis of glassy dimethacrylate networks as a function of oligomer structure, the type of reactive diluent, composition and curing conditions. A novel cycloaliphatic dimethacrylate was synthesized and its networks were compared to oligomeric structures containing dimethacrylates derived from epoxy terminated oligomers (from bisphenol-A and epichlorohydrin). Both types of dimethacrylates co-cured with methyl methacrylate exhibited increases in Mc and fracture toughness as the concentration of methyl methacrylate was increased. By contrast, networks prepared with a styrene diluent displayed reduced toughness with increasing styrene and Mc.
Due to the need for long-term composite environmental durability, the effects of moisture and exposure to sunlight are important. Thus, these materials were exposed to ultraviolet light on a rotating drum for 225 days and the exposure was carefully monitored. Initial results from this study suggest that both the networks comprising the aromatic dimethacrylate/styrene structures as well as the cycloaliphatic analogues cured with methyl methacrylate undergo reductions in rubbery moduli upon aging under these conditions. X-Ray photoelectron spectroscopy shows higher levels of oxidation on the bisphenol-A vinyl ester networks cured with styrene, especially those containing dimethylaniline and cobalt naphthenate as accelerators. Scanning electron microscopy indicates a smooth surface for the cycloaliphatic networks cured with methyl methacrylate and a pitted surface for the aromatic networks cured with styrene. Water absorption is also higher for the cycloaliphatic vinyl ester; however, curing with a longer alkyl chain methacrylate (butyl methacrylate) decreases the water absorption to levels comparable to those cured with styrene.Ph. D.
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Awwad, Monzer. "Synthèse de nouveaux outils moléculaires pour l’imagerie in vivo d’oligo- et polysaccharides à la surface cellulaire." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112174/document.
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La première partie de ce travail est réalisé dans le but de préparer des produits pouvant jouer un rôle très important de l’imagerie cellulaire des lipopolysaccharides sur la surface des cellules bactériennes, tout en utilisant des méthodes fiables telle que la ‘’chimie click’’. Dans un premier temps, nous avons synthétisé une première génération d’outils fluorescents à base de rhodamine B et fluorescéine modifiée par une fonction oxyde de nitrile. Dans un deuxième temps nous avons cherché les meilleures conditions d’applications de la chimie click 3+2 sans cuivre, entre la fonction oxyde de nitrile et le motif saccharidique complémentaire portant une fonction vinylique. Finalement, nous avons appliquée, avec succès, la méthode click avec cuivre sur plusieurs types de bactéries portant sur leur membrane cellulaire des lipopolysaccharides ayant un motif ‘’Kdo’’ fonctionnalisé par un groupement azoture déjà synthétiser au sein de notre équipe, et une sonde fluorescente porteuse d’une fonction alcyne. Une nouvelle génération d’outils de marquage saccharidique est en cours de finalisation dans le but d’optimiser les conditions finales, tel que le dérivé de ‘’Kdo’’ fonctionnalisé cette fois-ci par des dérivées cycliques, bicycliques et aromatiques porteurs d’une fonction alcyne ou alcène, pour réaliser les derniers essais de marquage in vitro. Le stress oxydant est lié au vieillissement des cellules et à de nombreuses maladies: cardiovasculaire, cancer, diabète, Alzheimer… Il est dû à un déséquilibre entre le système oxydant / antioxydant au niveau des cellules, et se caractérise par la présence principalement de substance radicalaires réactives oxygénées. Dans le but d'identifier le taux de substances réactives oxygénées dans les cellules, le travail dans la deuxième partie de la thèse reposait sur la synthèse multi étape d'une molécule fluorescente dérivée de la coumarine. Le composé ciblé est le peroxyde d'oxygène, connu sous le nom d'eau oxygénée. Possédant un ester vinyl-boronique, notre molécule sera oxydée et réarrangée en aldéhyde conduisant à la condensation intramoléculaire avec le groupement aminé adjacent pour former un cycle indolique, libérant ainsi de la fluorescence. La recherche des conditions optimales de la dernière étape de la voie synthétique sont toujours en cours d’optimisation. Dans le futur, on cherchera les conditions optimales de la dernière étape de la synthèse de la sonde spécifique au peroxyde d’oxygène. Cette molécule est d'une importance remarquable comme sonde du stress oxydant. En réussissant cette étape, on pourra avoir en main une bibliothèque de ‘’KDO’’ fonctionnalisé afin d’avoir des résultats satisfaisants in vivoThe first part of this work is done in order to prepare products that play a very important role in cellular imaging lipopolisaccharides on the surface of bacterial cells, while using reliable methods such as '' click chemistry ''. Initially, we synthesized the first generation of tools based fluorescent rhodamine B and fluorescein -modified nitrile oxide function. In a second step we sought the best possible applications of click chemistry 3+2 copper free, between the nitrile oxide function and the additional saccharide unit with a vinyl function. Finally, we applied successfully, the click method with copper on several types of bacteria on their cell membrane lipopolysaccharides having a pattern Kdo functionalized azide group already synthesized within our team, and a probe carrying a fluorescent alkyne. A new generation of tools saccharide marking is being finalized in order to optimize the final terms, such as derivative functionalized Kdo this time by cyclic, bicyclic and aromatic derivatives holders of an alkene or alkyne function to perform final testing of in vitro labeling. Oxidative stress is linked to cell aging and many diseases: cardiovascular disease, cancer, diabetes, Alzheimer's ... It is due to an imbalance between oxidant system/antioxidant in cells, and is characterized mainly by the presence of radical substance reactive oxygen. In order to identify the rate of reactive oxygen substances in cells, work in the second part of the thesis based on multi- step synthesis of a fluorescent molecule derived from coumarin. The target compound is oxygen peroxide, known as the name of hydrogen peroxide. Having a vinyl boronic ester, this molecule will be oxidized and rearranged aldehyde leading to intramolecular condensation with the adjacent amino group to form an indolique ring , thereby releasing fluorescence. The search for optimal conditions for the last step of the synthetic pathway is still being optimized. In the future, the optimal conditions for the last step of the synthesis of specific probe oxygen peroxide are sought. This molecule is remarkable importance as a probe of oxidative stress. By passing this step, we will have on hand a library of KDO functionalized to have satisfactory results in vivo
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Buck, Stephanie E. "Combined effects of moisture, temperature, fiber architecture, and sustained load on the mechanical and microstructural properties of notched and unnotched e-glass/vinyl ester composite materials /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9952663.
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Boumarafi, Abdelkader. "Évaluation des propriétés physiques et mécaniques et les effets des cycles gel-dégel de composites fabriqués par enroulement filamentaire." Mémoire, Université de Sherbrooke, 2014. http://hdl.handle.net/11143/5928.
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Résumé : Le développement des matériaux composites et leur utilisation dans le domaine du génie civil ont fait l’objet d’une recherche extensive sur le renforcement des structures en béton armé. Dans ce contexte, les études sur la compréhension du comportement structural des tubes en matériaux composites (Polymère renforcé en Fibre, PRF) sont indispensables. De fait que les matériaux composites sont innovateurs, cela nous exige de procéder à des investigations expérimentales approfondies pour vérifier les hypothèses et les théories, avant de les produire à échelle industrielle.
Ce projet présente une étude expérimentale approfondie sur l’évaluation des propriétés physiques et mécaniques des nouveaux tubes en matériaux composites (PRF), et des tests sur la durabilité du matériau utilisé, et permet d’étudier l’influence de quelques facteurs environnementaux sur ces propriétés mécaniques, ces conditions sont simulées par une immersion prolongée en milieu aqueux et l'exposition à des cycles gel-dégel en milieu humide. Les tubes considérés sont produits par le procédé d’enroulement filamentaire à l’aide des fibres de verre (E) et de résine (Vinyle-Ester). Les expérimentations seront effectuées sur des échantillons normalisés prélevés à partir du tube.
Les résultats de cette étude sont d’une importance cruciale pour comprendre le comportement structural (avant et après un vieillissement accéléré) des nouveaux tubes fabriqués entièrement en polymères renforcés de fibres par le procédé de l’enroulement filamentaire. // Abstract : The development of composite materials and their integration in the field of civil engineering
has been the subject of extensive research on strengthening reinforced concrete structures. In
the perspective of strengthening concrete structures by tubes made of composite materials. In
this context, the need for knowledge of the structural behaviour of tubes made from fibre
reinforced polymer (FRP) composite materials is prominent. The large using of innovativeFRP
required extensive theoretical and experimental investigations.
This project presents an experimental study to evaluate both the physical and mechanical
properties of FRP-composites tubes, and to investigate the impact of some environmental
factors on their mechanical properties. The tubes are produced by a filament winding process
using fibre (E)-glass and vinyl-Ester resin. The experiments will be performed on standardized
samples of the tube.
The main objective of this project is to assess the physical and mechanical properties of
laminated FRP composites, and then test the durability of the material used in the manufacture
of the tubes. It leads to the study of the effects of some environmental factors on the
mechanical properties of material. These conditions occur during an immersion in an aqueous
medium and exposure to freeze-thaw cycles.
The results of this study are crucial to understand the structural behavior (before and after
accelerated aging) of new FRP tubes made by filament winding process.
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Liu, Chenwei. "Synthesis of hyperbranched polymethacrylates by a bromoinimer approach." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1516719917076675.
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Delattre, Émilie. "Fonctionnalisation de polymères et applications en cosmétique." Phd thesis, Université Nice Sophia Antipolis, 2013. http://tel.archives-ouvertes.fr/tel-00918532.
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L'alcool polyvinylique a été fonctionnalisé avec des aldéhydes et des acides boroniques dans le but d'obtenir des polymères pouvant apporter de la brillance tout en étant solubles dans les formulations de rouges à lèvres ou de vernis à ongles. De bons taux de fonctionnalisation ont été obtenus permettant d'avoir une bibliothèque de poly(vinyl acétals) et de poly(vinyl esters boroniques) d'une cinquantaine de polymères. Une multi-fonctionnalisation du PVA a été effectuée pour obtenir des polymères alliant ces deux propriétés. Cinq poly(vinyl acétals) ont ainsi permis d'apporter une forte brillance à des rouges à lèvres. La E-poly-L-lysine a également été fonctionnalisée avec diverses cétones afin d'obtenir de nouvelles poly-4-imidazolidinones. Ces polymères sont prometteurs pour des applications dans des produits cosmétiques tels que des soins. Ils ont également été utilisés en catalyse organique asymétrique.
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Xu, Liqun. "Integrated analysis of liquid composite molding (LCM) processes." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1095688597.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xix, 245 p.; also includes graphics. Includes bibliographical references (p. 233-245).
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Harris, Linda Ann. "Polymer Stabilized Magnetite Nanoparticles and Poly(propylene oxide) Modified Styrene-Dimethacrylate Networks." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27547.
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Magnetic nanoparticles that display high saturation magnetization and high magnetic susceptibility are of great interest for medical applications. Nanomagnetite is particularly desirable because it displays strong ferrimagnetic behavior, and is less sensitive to oxidation than magnetic transition metals such as cobalt, iron, and nickel. Magnetite nanoparticles can be prepared by co-precipitating iron (II) and iron (III) chloride salts in the presence of ammonium hydroxide at pH 9-10. One goal of this work has been to develop a generalized methodology for stabilizing nanomagnetite dispersions using well-defined, non-toxic, block copolymers, so that the resultant magnetite-polymer complexes can be used in a range of biomedical materials.
Hydrophilic triblock copolymers with controlled concentrations of pendent carboxylic acids were prepared. The triblock copolymers contain carboxylic acids in the central urethane segments and controlled molecular weight poly(ethylene oxide) tail blocks. They were utilized to prepare hydrophilic-coated iron oxide nanoparticles with biocompatible materials for utility in magnetic field guidable drug delivery vehicles. The triblock copolymers synthesized contain 3, 5, or 10 carboxylic acids in the central segments with Mn values of 2000, 5000 or 15000 g/mol poly(ethylene oxide) tail blocks. A method was developed for preparing ~10 nm diameter magnetite surfaces stabilized with the triblock polymers. The carboxylic acid is proposed to covalently bind to the surface of the magnetite and form stable dispersions at neutral pH. The polymer-nanomagnetite conjugates described in this thesis have a maximum of 35 wt. % magnetite and the nano-magnetite particles have an excellent saturation magnetization of ~66 - 78 emu/g Fe3O4. Powder X-ray diffraction (XRD) confirms the magnetite crystal structure, which appears to be approximately single crystalline structures via electron diffraction spectroscopy analysis (EDS). These materials form stable magnetic dispersions in both water and organic solvents.Ph. D.
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Morin, Aurélie. "Controlled radical polymerization of vinyl esters and vinyl amides : experimental and theoretical studies." Thesis, Toulouse, INPT, 2013. http://www.theses.fr/2013INPT0117/document.
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Ces travaux de thèse portent sur la polymérisation radicalaire contrôlée (PRC) des esters et amides de vinyle. L’une des possibilités de contrôle est le piégeage dynamique réversible des chaînes radicalaires croissantes (P•) par un agent de contrôle (T) formant une espèce dormante (P─T’). La concentration en radicaux dans le milieu peut alors diminuer dramatiquement de sorte que les réactions indésirables de terminaisons soient négligeables et que le contrôle de la masse molaire des polymères soit atteint avec un faible indice de dispersité. L’utilisation de complexes métalliques, pouvant s’oxider et former une liaison métal-carbone, comme agent de piégeage des radicaux est une manière de réaliser ce contrôle. La PRC est alors appelée Polymérisation Radicalaire Contrôlée par voie Organométallique (OMRP). A ce jour, plusieurs métaux de transitions ont été utilisés avec plus ou moins de succès en OMRP. Lors de cette étude, nous avons synthétisé des complexes de cuivre(I) et testé leurs performances pour l’OMRP de l’acétate de vinyle et de l’éthylène. Nous avons également utilisé des outils de chimie théorique pour mieux comprendre pourquoi le cobalt(II) acétylacétonate est, jusqu’à aujourd’hui, le meilleur agent de contrôle pour la polymérisation de l’acétate de vinyle et des amides de vinyle. Grâce à la théorie de la fonctionnelle de densité (DFT), nous avons mis en lumière le rôle crucial de la coordination sur le cobalt des groupements carbonyles des monomères étudiésThis thesis focus on Controlled Radical Polymerization (CRP) of vinyl esters and vinyl amides. One of the possibilities to achieve this control is a dynamic reversible trapping of the growing radical chains (P•) by a controlling agent (T) to form a dormant species (P─T’). The radical concentration in the medium can be dramatically reduced so that the unwanted terminations are disfavored and polymers with controlled molecular weights and low dispersity can be obtained. A way to achieve this control is the use of metallic complexes, which can oxidize and form a metal-carbon bond, as trapping agent in the so-called Organometallic Mediated Radical Polymerization (OMRP). So far, different transition metals have been used with gretaer or smaller success. In this study, the synthesis of copper(I) complexes and their investigation for the vinyl acetate and ethylene polymerization under OMRP conditions were performed. We also used computational chemistry as a tool to better understand why the cobalt(II) acetylacetonate (Co(acac)2) has, so far, given the best results for either vinyl acetate or vinyl amides polymerization. Thanks to Density Functional Theory (DFT), the crucial role of the monomer carbonyl group coordination to cobalt was pointed out
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Boivin, Sylviane. "Modification chimique du polychloroformiate de vinyle dans les conditions de la catalyse par transfert de phase : étude d'un nouveau complexe de transfert de charge macromoléculaire à base de carbazole." Paris 6, 1986. http://www.theses.fr/1986PA066482.
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Brand, Jérémie. "Fonctionnalisation chimique des nanocristaux de cellulose par acylation avec les esters de vinyle : impact sur les propriétés de revêtements chargés en nanocellulose." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0318/document.
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Ce travail de thèse a pour objectif d’élaborer de nouveaux revêtements composites en utilisant les nanocristaux de cellulose (NCC) comme additifs biosourcés. Pour pallier au problème d’incompatibilité entre les charges hydrophiles et les matrices hydrophobes, une méthode simple à partir des esters de vinyle a été développée pour fonctionnaliser la surface des NCC. Une étude préliminaire réalisée à partir de l’acétate de vinyle utilisé comme réactif modèle, a d’abord permis d’optimiser les conditions de réaction. Ce protocole expérimental a ensuite été étendu à d’autres esters de vinyle fonctionnels, confirmant le caractère polyvalent de la méthode. Les NCC non modifiés et acétylés ont été dispersés dans des matrices acryliques (latex) ou polyuréthane (réticulable), afin d’étudier leur impact sur les performances mécaniques et barrières des composites. Une amélioration des propriétés mécaniques et barrières à l’oxygène a pu être observée dans certains cas, mais l’acétylation de surface des NCC n’a pas conduit à de meilleures performances. Une solution bicouches constituée d’un film 100 % NCC acétyles recouvert de polymère a alors été envisagé et a d’augmenter fortement les propriétés barrières à l’oxygène des différents matériaux. Certains NCC fonctionnalisés ont également été dispersés dans une matrice polydiméthylsiloxane, potentiellement utilisable comme revêtement protecteur pour l’aérospatial. Une amélioration notable de la stabilité thermique et optique sous irradiations UV dans des conditions géostationnaires a alors été observéeThe objective of this research work consist in the elaboration of novel compositecoatings using cellulose nanocrystals (CNC) as biobased additives. To palliate the problem ofincompatibility between the hydrophilic filler and the hydrophobic matrices, a simple methodbased on vinyl esters was developed to functionalize the CNC surface. A preliminary studyperformed with vinyl acetate selected as model reactant first allowed optimizing the reactionconditions. This experimental protocol was subsequently extended to other functional vinylesters to confirm the versatility of the method. The unmodified and acetylated CNC weredispersed in acrylic polymers (latex) or polyurethane (cross-linked resin) matrices, to studytheir impact on the mechanical and barrier performances of the composites. An improvementof the mechanical and barrier properties could be observed in some cases, but the CNCacetylation did not improve further the performances. A bi-layer approach consisting in afilm of 100 % of acetylated CNC coated with the polymer was then envisaged, and allowedincreasing significantly the oxygen barrier properties of the different resins. Some of thefunctionalized CNC were incorporated into a polydimethylsiloxane matrix, for a potential useas protective aerospace coating. A significant improvement in thermal stability and in opticalstability under UV irradiation in geostationary conditions was then observed
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Römhild, Stefanie. "Transport Properties and Durability of LCP and FRP materials for process equipment." Doctoral thesis, KTH, Polymera material, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-13221.
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This thesis focuses on transport properties and durability of liquid crystalline polymers (LCP)and fibre reinforced plastics (FRP) with regard to application in industrial process equipment.In the first part of the study the possibility of using a thermotropic LCP of type Vectra A950as lining material for FRP process equipment was investigated. Its performance wascompared to that of a fluorinated ethylene propylene copolymer (FEP) with respect tochemical and permeation resistance. Transport property and chemical resistance data wereestablished for different types of LCP film (compression molded, uniaxially and biaxiallyoriented film) exposed to selected chemicals chosen to represent typical industrial processenvironments. Annealing of the LCP, which may reduce the disclination density and henceimprove the barrier properties, induced a crystallinity increase, but did not significantlyimprove the barrier and chemical resistance properties. Different surface treatments toincrease the bonding between the LCP and FRP were explored. The conclusion was that LCPhas potential to serve as lining material for FRP in contact with water, organic solvents andnon-oxidizing acid environments, although certain issues, such as jointing techniques, stillhave to be evaluated. The second part of the study focused on transport and long-termproperties of commercial thermoset and FRP materials for industrial process equipment inaqueous environments (50 – 95 °C, water activity 0.78 – 1, exposure time ≤ 1000 days). Thewater transport properties in different thermosets were related to their chemical structureusing the solubility parameter concept. The transport of water in the thermosets with differentchemical structures could be predicted from the water activity, regardless of the actual type ofionic or non-ionic solute in the solution. An empirical relationship, independent of boththermoset chemistry and temperature, was established to describe the water concentration inthe thermoset as a function of water activity and the water concentration in pure water. Inlong-term, the water concentration in the thermosets increased with exposure time. Thisseemed to be primarily related to stress relaxation processes induced by water absorption andcertain leaching effects. The effects of hydrolysis seemed to be small. The glass fibrereinforcement may to various extents affect the water transport properties by capillarydiffusion and additional absorption around fibre bundles. The extent of such processesseemed to depend on temperature, water activity and the type of thermoset and reinforcement.The present work may be a useful contribution to an increased understanding of water effectsand durability of FRP process equipment. However, open questions still remain for a morecomprehensive durability analysis.QC20100629
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Blach, Stephan. "Kinetics of curing of a vinyl ester resin." Thesis, 1993. http://spectrum.library.concordia.ca/3563/1/MM87301.pdf.
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"Dispersion of carbon nanotubes in vinyl ester polymer composites." Thesis, 2010. http://hdl.handle.net/1911/62182.
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This work focused on a parametric study of dispersions of different types of carbon nanotubes in a polymer resin. Single-walled (SWNTs), double-walled (DWNTs), multi-walled (MWNTs) and XD-grade carbon nanotubes (XD-CNTs) were dispersed in vinyl ester (VE) using an ultra-sonic probe at a fixed frequency. The power, amplitude, and mixing time parameters of sonication were correlated to the electrical and mechanical properties of the composite materials in order to optimize dispersion. The quality of dispersion was quantified by Raman spectroscopy and verified through optical and scanning electron microscopy. By Raman, the CNT distribution, unroping, and damage was monitored and correlated with the composite properties for dispersion optimization. Increasing the ultrasonication energy was found to improve the distribution of all CNT materials and to decrease the size of nanotube ropes, enhancing the electrical conductivity and storage modulus. However, excessive amounts of energy were found to damage CNTs, which negatively affected the properties of the composite. Based on these results the optimum dispersion energy inputs were determined for the different composite materials. The electrical resistivity was lowered by as much as 14, 13, 13, and 11 orders of magnitude for SWNT/VE, DWNT/VE, MWNT/VE, and XD-CNT/VE respectively, compared to the neat resin. The storage modulus was also increased compared to the neat resin by 77%, 82%, 45%, 40% and 85% in SWNT, SAP-f-SWNT, DWNT, MWNT and XD-CNT/VE composites, respectively. This study provides a detailed understanding of how the properties of, nanocomposites are determined by the composite mixing parameters and the distribution, concentration, shape and size of the CNTs. Importantly, it indicates the importance of the need for dispersion metrics to correlate and understand these properties.