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1
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.
2
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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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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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.
5
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
6
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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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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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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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.
10
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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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.
13
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.
14
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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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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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).
17
"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.
18
CHEN, WEI-JUN, and 陳威鈞. "Research on the pultrusion of glass fiber reinforced vinyl ester composites." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/89016023108603605113.
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Tweed-Kent, Sean P. Runt James P. Juska Thomas David. "Understanding cure inhibition in carbon fiber reinforced vinyl ester resin composites." 2008. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-3528/index.html.
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Teng, Shiao-hua, and 鄧孝華. "Study on the pultrusion of hybridized fiber reinforced vinyl ester composites." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/09643449001843780119.
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碩士文化大學
造紙印刷研究所
83
This study presents a proprietary process devoloped to manu- facture pultruded hybrided fiber reinforced VE composites. The effect of processing parameters on the mechanical properties ( flexural;tensile strength and modulus; impact strength ,etc.) of pultruded hybridized(Glass/Rayon) fiber reinforced vinyl ester ( VE) composites rates, die temperatures, postcure temperature and time,and hybridized fiber content. From the viscosity test , the optimum temperature of impreg- nation tank is set between in 25 and 50℃. The prepolymer has at least 8 hr pot life in order to let the fiber have enough time for processing. From the results of SEM fracture-surface , of longiltudinal and cross- section, the hybridized fiber have good wet-out. From the above disscussion,the VE resin have excellent processing for pultrusion. From the experiment results,the range of pulling rate is set 20~70cm/min , and the optimum pulling rate is 40cm/ min. From the DSC and mechanical properties investigation,the optimum die tem- perature and time is 120℃ and 1hr, respectively. The dynamic mechanical properties increased with the incre- assing of hybridized fiber content. The dynamic storage modulus (E'') of adding rayon fiber is better than that without of adding ,and the Tanδ（Tg) do not change due to the hybridized fiber don''t have an effect on Tg.
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Huang, Yen-Wei, and 黃彥瑋. "Preparation and Properties of Inorganic Material Coated Carbon Nanotube /Vinyl Ester Composites." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/93843087656979206228.
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碩士國立清華大學
化學工程學系
97
Recent advances in nanofabrication have enabled the continuing reduction in size of electronic devices. Smaller sizes have led to higher device density at the expense of increased power demand and the resultant heat generation. Electronic devices were damaged by much heat accumulation. The thermal management strategies are thus critically important to continue high performance, reliability and lifetime of devices. Carbon nanotubes possess low density, large aspect ratio and unique thermal properties that make carbon nanotubes be utilized as filler to fabricate nanocomposites. High thermal conductivity nanocomposites based on carbon nanotubes can be developed to assist heat conduction，however, high electrical conductivity of carbon nanotube provides the conductive path causing short circuit of the device at the same time. For solving this problem the technologies of coating inorganic materials on the carbon nanotube is proposed to hinder the electrical conducting channel. There are three chemical processes were proposed for fabricating multi-walled carbon nanotube (MWCNT) coated with inorganic materials. The carboxylic groups were first introduced on the MWCNTs using acid oxidation method for dispersing individual MWCNTs. In order to provide the interfacial interactions between the MWCNTs and the inorganic materials for self-assembly of the nanoinorganic layer, acid oxidized MWCNTs were reacted with a silane coupling agent. Finally, the molecular interaction between the silane functionalized MWCNTs and inorganic materials via sol-gel process was utilized to form the structure of inorganic layer coated on MWCNTs. MWCNTs coated with inorganic materials was analyzed by Raman spectrometer, X-ray photoelectron (XPS), Fourier transform infrared spectrometer (FT-IR) and thermogravimetric analysis (TGA). The morphology of MWCNTs coated with inorganic materials were observed by Transmission electron microscope (TEM).The effect of inorganic materials on the electrical resistivity and thermal conductivity of MWCNTs were investigated. The electrical resistivity of modified MWCNTs was increased 6 orders of magnitude than pristine MWCNTs by coating with inorganic materials .This result exhibits that inorganic layers successfully hinder the electrical conducting channel. The thermal conductivity of MWCNTs was increased from 6.44 W/mK to 8.19 W/mK.The enhancement is 27%. Vinyl ester resin possesses excellent adhesion, mechanical properties and resistance to chemicals, such as acids, alkalies, oxidizing chemicals and salt solutions, etc. However, the thermal conductivity of vinyl ester is too low to be utilized in thermal applications. In this study, MWCNTs coated with inorganic materials were added in vinyl ester to fabricate high thermal conductivtiy and electrical insulation nanocomposite. Inorganic materials coated on MWCNT/vinyl ester nanocomposites were also prepared to investigate the electrical resistivity, the thermal conductivity, glass transition temperature (Tg) and coefficient of thermal expansion (CTE).Results show that inorganic materials coated on MWCNTs can reduce the CTE of nanocomposites and increase Tg, the thermal conductivity of nanocomposites while retain electrical insulation at same time. SEM microphotographs show that the inorganic materials coated on MWCNT / Vinyl ester nanocomposites possess better compatibility and disperity. The volume electrical resistivity decreased 14 orders of magnitude from 7.8 x1015 (ohm*cm) to 4.8 x101 (ohm*cm) with 10phr(parts per hundred parts of resin) of MWCNT. On the other hand, the volume electrical resistivity of Al2O3@SA-MWCNT/vinyl ester nanocomposites decreased slightly from 7.8 x1015 (ohm*cm) to ~5x1012 (ohm*cm).The volume electrical resistivity of nanocomposites decreased only 3 orders of magnitude and maintained electrical insulation . Because the electrical networks of Al2O3@SA-MWCNT in the nanocomposites were hindered by the alumina coating layer. The thermal conductivity of the Al2O3@SA-MWCNT/vinyl ester nanocomposites increased from 0.13 W/mK to 1.12 W/mK when the content of the MWCNTs was increased from 0 to 10 phr. The enhancement is 757% .Tg of the Al2O3@SA- MWCNT/vinyl ester nanocomposites increased from 125. 8oC to 138.9oC when the content of the MWCNT was increased from 0 to 10 phr. The enhancement is 10.4 %.CTE of the Al2O3@SA-MWCNT/vinyl ester nanocomposites decreased from 79. 6 (10-6/K) to 56.2(10-6/K) when the content of MWCNT was increased from 0 to 10 phr.
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Tsai, Yun-Pang, and 蔡運邦. "Preparation and Mechanical Properties of Multiwalled Carbon nanotube-fiber Reinforced Vinyl Ester Composites." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/74230242200752545598.
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碩士國立清華大學
化學工程學系
100
In this study, Multi-walled carbon nanotube(MWCNT) was modified with different methods. The Allyl-MWCNTs were prepared via free radical reaction with allylamine, which contains the ethylene groups for increase interaction between MWCNTs and vinyl ester (VE). The TEVOS was grafted on the MWCNTs surface to prepare MWCNT-TEVOS. From the mechanical properties study, the tensile strength of glass fiber/vinyl ester was increased from 227.5MPa to 254.06MPa when 1phr P-MWCNT content was added to neat GF/VE composite. The tensile strength of GF/VE composites was increased to 258.55 MPa (with 1phr TEVOS-MWCNT) and to 275.45MPa (with 1phr Allyl-MWCNT). Modified MWCNT can improve the tensile strength of the GF/VE than that was added with unmodified MWCNT. The fracture toughness (GIC) of GF/VE composites was increased from 0.76 kJ/m2 (neat GF/VE) to 0.83kJ/m2 (with 0.25 phr MWCNT) and to 0.94 kJ/m2 (with 1.0phr TEVOS-MWCNT) and to 1.07 kJ/m2 (with 1.0phr Allyl-MWCNT). Allyl-MWCNT possesses the best interface bonding between fiber and matrix that exhibits best fracture toughness of these three kinds of composites. The Tg of GF/VE composite was 89.05℃. The GF/VE composite with 1phr TEVOS-MWCNT and Allyl-MWCNT shows the Tg which was 107.70℃, and 109.70℃ respectively. It indicated that thermal stability of composite can be improved even when a small quantity of functionalized MWCNTs was added From the mechanical properties study, the tensile strength of carbon fiber/vinyl ester was increased from 369.45MPa to 448.68MPa when 1phr P-MWCNT content was added to neat CF/VE composite. The tensile strength of CF/VE composites increased to 465.15MPa (with 1phr TEVOS-MWCNT) and to 476.45MPa (with 1phr Allyl-MWCNT). Modified MWCNT can improve the tensile strength of the CF/VE than that of unmodified MWCNT/CF/VE composite. The GO/CF/VE composites show the best tensile strength, which were 505.04MPa with 1 phr filler content. The flexural strength of CF/VE composites was increased from 272.45MPa (neat GF/VE) to 501.53 MPa (with 1.0 phr MWCNT) and to 511.45MPa (with 1.0phr TEVOS-MWCNT) and to 521.56MPa (with 0.5phr Allyl-MWCNT).Allyl-MWCNT/CF/VE composite possesses better flexural strength than that of unmodified MWCNT/CF/VE. The GO/CF/VE composites show the best flexural strength, which was 558.07MPa with 1 phr filler content. The fracture toughness (GIC) of CF/VE composites increased from 0.80 kJ/m2 (neat CF/VE) to 0.95kJ/m2 (with 0.5 phr MWCNT) and to 1.04 kJ/m2 (with 1.0phr TEVOS-MWCNT) and to 1.07 kJ/m2 (with 1.0phr Allyl-MWCNT). Allyl-MWCNT/CF/VE exhibits the best fracture toughness due to the improvement of interface bonding between fiber and matrix. The Tg of CF/VE composite was 98.18℃. The CF/VE composite with 1phr TEVOS-MWCNT and Allyl-MWCNT shows the Tg which was 115.67℃, and 116.67℃respectively. It indicated that thermal stability of composite can be improved even when a small quantity of functionalized MWCNTs was added.
23
Lin, Yu-Hung, and 林昱宏. "Research on the pultrusion of glass fiber and carbon fiber reinforced Vinyl ester composites." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/73175830547531667487.
Full textAbstract:
碩士中國文化大學
材料科學與製造研究所
93
This research presents a proprietary process developed to manufacture pultruded hybrid fiber reinforced vinyl ester composites. The effect of processing parameters on the properties of pultruded hybrid (glass/carbon) fiber reinforced unsaturated polyester composites have been studied. The processing parameters included optimum fiber content, die temperature, pulling rate, carbon fiber content of hybrid fiber, CaCO3 and Talc content, and postcure temperature and time. From the viscosity test, the optimum temperature of impregnation tank is set at 25℃. And the resin in 8 hours operating times (Pot Life) the viscosity range is 350~1360mPa．s, and suit to pultruded.Accoding to the result of SEM cross-section and fracture-surface, the hybrid fiber have good wet-out. From above results, the vinyl ester resin has excellent pultruded processing properties. The experiment results present the best fiber content is 64.84vol%; the optimum pulling rate is set at 40 cm/min. From the DSC and mechanical properties investigation, the optimum die temperature is set at 140℃. The flexural strength , impact strength of pultruded composites increase with decreasing carbon fiber content. The flexural modulus , Tanδ and dynamic storage modulus (E’) and heat weight stability increase with carbon fiber content. The flexural strength, the flexural modulus and impact strength reached a maximum value at 3~5 phr filler and then decreased.The postcure treatment,flexural strength, flexural modulus , impact strength increased at a suitable postcure temperature and time. The suitable postcure temperature and time were determined to 120℃ and 3hrs, respectively.
24
Wang, Yung-Jih, and 王勇日. "Research on the pultrusion of glass fiber reinforced blocked polyurethane modified vinyl ester composites." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/64486560405042938786.
Full textAbstract:
碩士中國文化大學
材料科學與製造研究所
89
This research presents a proprietary pultrued process developed to manufacture blocked polyurethane / vinyl ester composites. Based on the investigation of the pot life to the resin, the reactivity of the resin and fiber wet-out, it was found that blocked polyurethane / vinyl ester shows excellent processability for composites. The effect of processing parameters on the mechanical properties of pultruded glass fiber reinforced blocked polyurethane / vinyl ester composites has been studied. The processing parameters investigated included die temperature, blocked polyurethane content, pulling rate, filler type and content, and postcure temperature and time. This study also present a proprietary process developed to manufacture blocked polyurethane / vinyl ester composites. The effect of processing parameters on the mechanical properties of the composites has been studied. From the DSC and mechical properties tests, the suitable for die temperature range is 170℃~200℃, and the optimum die temperature is 190℃. From the experiment results, the suitable for pulling rate is between 20~80cm/min, and the optimum pulling rate is 60cm/min. The suitable for blocked polyurethane content is 10wt%. The mechanical properties increase at a suitable postcure temperature and time. Furthermore, the properties that decreased as a result of composite degradation after long postcure time. The suitsble temperature and time are 100℃ and 60 min, respectively.