Dissertations / Theses: 'Thermoplastic composites'

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Wu, Xiang. "Thermoforming continuous fiber reinforced thermoplastic composites." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/9383.

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Goel, Ashutosh. "Fatigue and environmental behavior of long fiber thermoplastic (LFT) composites." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008p/goel.pdf.

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Thesis (Ph. D.)--University of Alabama at Birmingham, 2008.
Additional advisors: Uday K. Vaidya, Derrick R. Dean, Nikhilesh Chawla, Mark Weaver. Description based on contents viewed Oct. 7, 2008; title from PDF t.p. Includes bibliographical references.

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Norpoth, Lawrence R. "Processing parameters for the consolidation of thermoplastic composites." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/19099.

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Bengtsson, Magnus. "Silane Crosslinked Wood-Thermoplastic Composites." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-680.

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Wood-thermoplastic composites are a more environmental friendly alternative for pressure-treated lumber but can also replace engineering plastic products. These composites have been on the market for more than ten years now and have mainly been used in building and automotive applications. The use of these materials has shown that long-term properties, durability, and toughness are the main problems. The aim of this study was to investigate if silane crosslinking could be one way of solving these problems. Silane crosslinked woodthermoplastic composites with polyethylene as the matrix and wood flour as reinforcement were manufactured by melt compounding. A reactive extrusion process was developed where compounding of polyethylene and wood flour and silane grafting were carried out simultaneously. The extrusion process was optimized and used in larger scale profiling of crosslinked composites. The composite materials were evaluated using chemical analysis, mechanical testing, spectroscopic analysis, thermal analysis, and electron microscopy. The crosslinking reaction was shown to be initiated during compounding of the composites and was significantly increased upon storage in a high humidity sauna at elevated temperature. The crosslinked composites showed toughness, impact strength and creep properties superior to the non-crosslinked composites. Scanning electron microscopy on the fracture surface of the crosslinked composites revealed good interfacial adhesion between the wood fibres and the polyethylene matrix. Based on results from this study, it is proposed that silane crosslinking creates a three dimensional network in the polyethylene matrix with chemical bonding to the wood fibres.

Future evaluation of results from accelerated weathering studies will reveal if silane crosslinking can improve the durability of wood-thermoplastic composites during outdoor exposure. Investigation of the potential of silane crosslinking on other type of composite systems with other thermoplastic matrices and natural fibres would also be of interest.

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Loh, Galay. "Thermoplastic composites in medical implants." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/11728.

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Li, Min-Chung. "Autohesion model for thermoplastic composites." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/51916.

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A non-isothermal autohesion model was developed by combining a transient finite element heat transfer model with the isothermal autohesion model. Heat transfer analyses and the interfacial strength development analyses were conducted using the non-isothermal autohesion model on a polysulfone (Udel P1700) compact tension specimen, a 64-ply graphic (Thomel T300)/P1700 unidirectional composite, and a 192-ply graphite (Hercules AS4)/P1700 unidirectional composite. A 64-ply T300/P1700 unidirectional composite was processed in a matched metal mold. Temperature data were taken and compared with the calculated values. Good agreement was observed between the calculated and the measured temperature values. A healing test which aimed at studying the interplay bond development in AS4/P1700 unidirectional composites was performed. The double cantilevered beam (DCD) Mode l fracture toughness test was selected. The DCB specimens were fractured and healed in a special fixture with different combinations of temperature pressure, and time. The healed DCB specimens were refractured and the critical strain energy release rates (G_IC) were measured. The pressure was found to be a key factor in the healing process. Temperature and time dependencies of the interply bond development were also observed. The non-isothermal autohesion model predicted a higher strength achieved in a shorter time. This was due to the extra time which was needed for the fracture interface to achieve intimate contact, and the assumption of the initial intimate contact achievement of the non-isothermal autohesion model.
Master of Science

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Chevali, Venkata Sankaranand. "Flexural creep of long fiber thermoplastic composites effect of constituents and variables on viscoelasticity /." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2010r/chevali.pdf.

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Thesis (Ph. D.)--University of Alabama at Birmingham, 2010.
Title from PDF t.p. (viewed June 30, 2010). Additional advisors: R. Michael Banish, Derrick R. Dean, Nasim Uddin, Uday K. Vaidya. Includes bibliographical references (p. 197-202).

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Li, Min-Chung. "Thermoplastic composite consolidation." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40036.

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Fabrication of high-quality composites from thennoplastic prepregs requires careful selection of the processing cycles so that intimate contact at the ply interfaces is achieved resulting in the formation of strong interply bonds and the process-induced residual stress is minimized to ensure superior mechanical performance. The void formation and the consolidation mechanism were studied experimentally. A refined model was developed to relate the processing parameters of pressure, temperature and time to the interply intimate contact of thermoplastic composites. The model was developed by integrating a prepreg surface topology characterization with a resin flow analysis. Both unidirectional and cross-ply lay-ups were modeled. Two-ply unidirectional laminae fabricated from graphite-polysulfone and graphite-PEEK prepregs and [0/90/0]_T laminates were consolidated using different processing cycles. Optical microscopy and scanning acoustic microscopy were used to obtain the degree of intimate contact data. Agreement between the measured and calculated degree of intimate contact was good. A finite element model was developed to analyze residual stresses in thermoplastic composites by combining a plane-strain elasticity analysis and a temperature-dependent matrix properties. The residual stress model takes into account the mismatch of the thermal expansion coefficients and the crystallization shrinkage of the matrix. [O₁₀/90₆]_T graphite-PEEK laminates were manufactured at different cooling rates to verify the model. The induced residual thermal defonnations were measured by a shadow moire system. The model accurately estimated the out-of-plane displacement of the non-symmetrical laminates.
Ph. D.

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Yang, Heechun. "Modeling the processing science of thermoplastic composite tow prepreg materials." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/17217.

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Howes, Jeremy C. "Interfacial strength development in thermoplastic resins and fiber-reinforced thermoplastic composites." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/77899.

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The objective of this study was to develop tests that could be used to characterize autohesive strength development in amorphous thermoplastic resins and fiber-reinforced thermoplastic prepregs. All tests were performed using polysulfone P1700 thermoplastic resin and AS4/P1700 graphite-polysulfone prepreg. Two test methods were examined to measure autohesion in neat resin samples. These included an interfacial tension test based on the ASTM tensile adhesion test (ASTM D897) and a fracture toughness test using a compact tension (CT) specimen (based on the ASTM toughness test for metals ASTM E399-83). The interfacial tensile test proved to be very difficult to perform and with an unacceptable amount of data scatter. The data obtained using the compact tension test were repeatable and could be correlated with temperature and contact time. Autohesive strength development in fiber-reinforced prepreg samples was measured using a double cantilever beam (DCB) interlaminar fracture toughness test. The fracture mechanisms were determined to be different in the healed DCB specimen than the virgin specimen due to resin flow at the crack plane during the healing tests. The CT test was found suitable for use in determining the autohesive properties and self-diffusion coefficient of neat resin. The DCB test, although not suitable for autohesive testing, indicated that repair of thermoplastic matrix composites is possible; however, the repair will not be as tough as the virgin material.
Master of Science

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Grubbström, Göran. "Reactive extrusion of wood-thermoplastic composites." Licentiate thesis, Luleå tekniska universitet, Materialvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16932.

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The interest in Wood-thermoplastic composites (WPCs) has increased during the last decades. WPCs are commonly used as building material for decking and railing because of its low need of maintenance. Wood is a renewable resource of good mechanical properties and this make wood fibers interesting to use as reinforcement in a thermoplastic composite. A drawback with this type of composite is the poor long-term mechanical properties which limit its field of applications. The objective of this work was to optimize the process and understand structure-property relations of silane-crosslinked WPCs produced in a one-step reactive extrusion. The specific goal of crosslinking the composite was to improve the interfacial strength and stabilize the polymer matrix in order to improve these composites long-term mechanical properties.Silane-crosslinked WPC was produced by adding wood flour, polyethylene and a silane-peroxide solution to a compounding extruder. The composites were thereafter conditioned in different environments to promote the formation of silane-crosslinks. Parameters like wood flour moisture content, amount/composition of silane-peroxide solution and different general types of polyethylene was studied and related to the efficiency of the process.It was found that silane-technology applied to WPCs can be optimized in terms of processability and achieved property improvements. All crosslinked composites in this study have improved in strength, toughness and creep resistance but it was shown that the tested parameters have affect on both processing and properties. A gentle use of peroxides in the process was concluded to be positive for both processability and resulting property improvements. The unintentional crosslinking in the extrusion process is a drawback but was limited by lower peroxide concentrations. The use of low density polyethylene as polymer matrix lead to twice as high crosslinking rate compared to a high density polyethylene matrix. However, too excessive moisture uptake in the composites appears to lower the efficiency of crosslinking. Future studies should evaluate long-term load behavior more thoroughly and also investigate the conditioning step more carefully.
Godkänd; 2009; 20090922 (grubb)

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Kodokian, George-Kevork. "Adhesive bonding of thermoplastic fibre-composites." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/8815.

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Kiziltas, Alper. "Microcrystalline Cellulose-Filled Engineering Thermoplastic Composites." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/KiziltasA2009.pdf.

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Trende, Andreas. "Thermal issues in thermoplastic composites manufacturing /." Stockholm, 1999. http://www.lib.kth.se/abs99/tren0603.pdf.

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Benatar, Avraham. "Ultrasonic welding of advanced thermoplastic composites." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14668.

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Devlin, Brendan James. "The pultrusion of thermoplastic matrix composites." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260359.

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Shih, Po-Jen. "On-Line Consolidation of Thermoplastic Composites." Diss., A&T Access:, 1997. http://scholar.lib.vt.edu/theses/public/etd-135510112972690/etd-title.html.

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Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1997.
"UMI number: 9724066"--T.p. verso. Vita. Includes bibliographical references (p. 182-189). Available electronically via Internet.

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Grubbström, Göran. "Reactive extrusion of wood-thermoplastic composites /." Luleå : Luleå university of technology, 2009. http://pure.ltu.se/ws/fbspretrieve/3112390.

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Peterson, Nels Royal. "Wood-thermoplastic composites manufactured using beetle-killed spruce from Alaska's Kenai Peninsula." Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Summer2008/N_Peterson_060508.pdf.

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Mattheyse, Richard. "Application of commingled thermoplastic composites on an airline seat backrest." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2132.

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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: Thermoplastic composites (TPCs) have shown significant advantages over thermosetting composites. They have only been put into use recently and global knowledge in TPCs is often proprietary, therefore a study into the application, processing and properties is of importance. The aim of the study is to contribute knowledge in TPCs for South African industry and academic institutions. This thesis studies continuous fibre reinforced thermoplastics (CFRTPs), focussing on the autoclave processing of commingled CFRTPs. A literature study provided background knowledge to CFRTPs regarding processing techniques and mechanics. Flexural testing and impact testing were performed on a variety of CFRTPs and thermosetting composites (TSCs). These tests were performed to further understand CFRTPs as well as to compare CFRTPs and TSCs. The flexural testing revealed that CFRTPs have comparable strength and stiffness to the TSCs that were tested. They also revealed that pre-consolidated sheets showed better and more consistent properties than sheets made from commingled fabric. The impact testing revealed that the tested CFRTPs and TSCs had similar impact resistance even though thermoplastic composites are supposed to be more impact resistant. The tests also showed that thick unreinforced thermoplastics had much higher impact resistance than the reinforced materials. Manufacturing experiments were performed to establish sound processing methods of CFRTPs. It was realised here that the high temperatures required to process the materials require specific processing consumables and tooling. The experiments began by processing flat panels in a convection oven with vacuum bagging techniques. They then progressed to autoclave processing of parts with complex geometry. An airline seat backrest was chosen as the case study in the application of CFRTPs. This application requires structural strength and stiffness and also has strict fire, smoke, toxicity and heat release (FSTH) requirements. Its geometry was sufficiently complex to demonstrate the use of commingled CFRTP material. Backrests were made from both CFRTPs and TSCs so that a comparison could be made between the two types. The backrest was modelled using finite element methods (FEM) to determine an adequate lay-up. This lay-up was then used for both the CFRTP and TSC backrests to ensure similarity between the backrests of both materials. LPET (modified polyethylene terephthalate) was the chosen thermoplastic matrix as it was more attainable than PPS (polyphenylene sulphide) CFRTPs. The backrests of both materials were manufactured in an autoclave with a vacuum bag method and then assembled using adhesives and bonding jigs. Testing revealed that the stiffness and mass of the CFRTP backrests were very similar to the epoxy backrests. This implies that commingled CFRTPs can replace the use of TSCs in similar applications. A basic cost comparison was also performed to compare the manufacture of CFRTP backrests to TSC backrests. Further work is needed to optimise processing time of these materials to make them more competitive with TSCs. The processing time of commingled materials will probably never be as quick as that of press formed pre-consolidated sheets. Their ability to be formed into more complex parts does however make their use advantageous.
AFRIKAANSE OPSOMMING: Termoplastiese saamgestelde materiale (Engels: thermoplastic composites (TPCs)) toon beduidende voordele bo termoverhardbare saamgestelde materiale. Hulle word eers sedert onlangs benut en algemene kennis in TPCs is dikwels patentregtelik, dus is ’n studie van die aanwending, prosessering en eienskappe daarvan van belang. Die doel van hierdie studie is om ’n bydrae te lewer tot die kennis van TPCs vir die Suid-Afrikaanse industrie en akademiese instellings. Hierdie tesis ondersoek kontinue veselversterkte termoplastieke (Engels: continuous fibre reinforced thermoplastics (CFRTPs)) en fokus op die outoklaafprosessering van vermengde (Engels: commingled) CFRTPs. ’n Literatuurstudie het die agtergrondkennis rakende die prosesseringstegnieke en meganika van CFRTPs verskaf. Buigtoetsing en impaktoetsing is op ’n verskeidenheid CFRTPs en termoverhardbare saamgestelde materiale (Engels: thermosetting composites (TSCs)) uitgevoer. Hierdie toetse is uitgevoer om CFRTPs beter te verstaan asook om CFRTPs en TSCs te vergelyk. Die buigtoetsing het onthul dat CFRTPs ooreenstemmende sterkte en styfheid het as die TSCs wat getoets is. Dit het ook getoon dat vooraf-gekonsolideerde plate beter en meer konsekwente eienskappe getoon het as plate wat van vermengde materiaal gemaak is. Die impaktoetsing het onthul dat die CFRTPs en TSCs wat getoets is soortgelyke impakweerstand gehad het, selfs al is termoplastiese saamgestelde materiale veronderstel om meer impakweerstand te toon. Die toetse het ook getoon dat dik onversterkte termoplastieke veel hoër impakweerstand gehad het as die versterkte materiale. Vervaardigingseksperimente is uitgevoer om betroubare prosesseringsmetodes vir CFRTPs vas te stel. Daar is besef dat die hoër temperature wat vereis word om die materiale te prosesseer ook spesifieke prosesseringsverbruiksware en -gereedskap benodig. Die eksperimente het begin met die prosessering van reguit panele in ’n konveksie-oond met vakuumsaktegnieke. Daar is toe aanbeweeg na die outoklaafprosessering van onderdele met komplekse geometrie. Die rugleuning van ’n vliegtuigsitplek is gekies as die gevallestudie in die gebruik van CFRTPs. Hierdie toepassing vereis strukturele sterkte en styfheid en is ook onderhewig aan streng vereistes t.o.v. brand, rook, toksisiteit en hittevrystellimg (Engels FSTH). Die geometrie daarvan was kompleks genoeg om die gebruik van vermengde CFRTP-materiaal te demonstreer. Rugleunings is gemaak van beide CFRTPs en TSCs sodat ’n vergelyking tussen die twee tipes gemaak kon word. Die rugleuning is gemodelleer deur eindige element metodes (EEM) te gebruik om ’n aanvaarbare oplegging te bepaal. Hierdie oplegging is toe gebruik vir beide die CFRTP en TSC rugleunings om die gelykvormigheid tussen die rugleunings van beide materiale te verseker. LPET (Engels: modified polyethylene terephthalate) was die gekose termoplastiese matriks aangesien dit meer verkrygbaar was as PPS (Engels: polyphenylene sulphide) CFRTPs. Die rugleunings van beide materiale is vervaardig in ’n outoklaaf met ’n vakuumsakmetode en toe geintegreer deur die gebruik van kleefstowwe en setmate. Toetsing het getoon dat die styfheid en massa van die CFRTP rugleunings baie soortgelyk was aan die epoksie rugleunings. Dit impliseer dat vermengde CFRTP die plek van TSCs in soortgelyke gebruike kan inneem. ’n Basiese kostevergelyking is ook gedoen om die vervaardiging van CFRTP-rugleunings teenoor TSC-rugleunings te vergelyk.

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Cantrill, John. "Structural integrity of reinforced thermoplastic pipes." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250104.

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Oksman, Kristiina. "Improved properties of thermoplastic wood flour composites." Doctoral thesis, Luleå tekniska universitet, Materialvetenskap, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26513.

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In this study the properties of composites made of wood flour and thermoplastics have been investigated. In order to improve the interfacial adhesion between hydrophobic and nonpolar thermoplastics and hydrophilic and polar wood flour different additives have been used as compatibilizers in composites systems. The interaction between a wood filler and thermoplastic matrix, with and without compatibilizers, has been studied using conventional mechanical testing, impact testing, dynamic mechanical thermal analysis (DMTA), electron microscopes and infrared spectroscopy. Tests of mechanical properties, such as maximum tensile strength, tensile modulus and impact strength have shown that maleic anhydride grafted styrene-ethylene/butylene-styrene triblock copolymer (SEBS-MA) acts as a compatibilizer in the composite system. The SEBS-MA improves the stress transfer from the matrix to the wood particles and forming an flexible interphase around the wood particle and therefore improves the impact properties. The DMTA measurements indicated that there is an interaction between the wood surfaces and the maleic anhydride part of the SEBS-MA copolymer, and also between PS and wood. Morphological studies with SEM and TEM showed that the addition of SEBS-MA improved the adhesion between the wood particles and polymer matrix and that the compatibilizer is located at the interphase region between them. An infrared spectroscopy study indicated that the MA in the SEBS may react with the wood by forming hydrogen- and esterbonds and also possibly interaction between PS and wood.
Godkänd; 1997; 20061128 (haneit)

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Carpenter, Charles E. "On-line consolidation mechanisms for thermoplastic composites." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/19266.

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Ijaz, Muhammad. "Vacuum consolidation of commingled thermoplastic matrix composites." Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413963.

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Parkyn, A. T. "Residual stresses in laminated thermoplastic matrix composites." Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234355.

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Steel, David Thomas. "The formability of long fibre thermoplastic composites." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392679.

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Dunn, Christopher Thomas 1971. "Thermoplastic active fiber composites for structural actuation." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16851.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002.
Includes bibliographical references (v. 2, leaves 267-276).
The integration of piezoelectric actuators into a structure can lead to an active structural surface that can adapt by bending or straining to different operational conditions. This can be used to tune desired properties of the active system to their optimal levels. Due to their fast response time, high bandwidth, and the level of force that the actuator can apply, it has been proposed that monolithic piezoelectric materials be used for active structural control. Monolithic piezoelectric materials for planar actuation have several drawbacks including: (a) use of the lower 3-1 actuation for planar actuation, (b) low strain before failure, (c) inability to conform to curved surfaces. Active Fiber Composites (AFCs) have been developed to address some of these shortcomings of monolithic piezoceramic materials. AFCs are thin composite plies comprised of unidirectional piezoelectric fibers imbedded in a thermoset matrix. An electric field is supplied to the fibers by use of an interdigitated electrode pattern adhered to either side of the AFC. The benefits of AFCs include: the interdigital electrode design uses 3-3 actuation offering increased levels of actuation, AFCs allows for anisotropic planar actuation, the AFCs matrix provides load transfer and load distribution, AFCs allows for coverage of curved shapes. A major drawback of the AFCs with PZT-5A fibers is that the level of actuation is 60% lower than that of the 3-3 actuation of monolithic PZT-5A. This is due primarily to a small layer of low dielectric matrix material that is trapped between the electrodes and the high dielectric fibers during manufacturing.
(cont.) This dielectric mismatch causes a large voltage drop in the matrix thereby reducing actuation. A method that has been developed to reduce this matrix gap, and thus increasing actuation, is to transfer the electrode pattern onto plastic sheets, and heat and press the sheets around the fibers to make Thermoplastic Active Fiber Composites (tmAFCs). tmAFCs also have simpler processing when compared to AFCs and are reshapeable. The focus of this research is to analyze, manufacture, and test tmAFCs to be used in structural control applications with the goal of producing high quality and high performance actuators.
by Christopher T. Dunn.
Ph.D.

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Crawley, Christopher Anthony. "Thermoforming of continuous fibre-reinforced thermoplastic composites." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263704.

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Choupin, Tanguy. "Mechanical performances of PEKK thermoplastic composites linked to their processing parameters." Thesis, Paris, ENSAM, 2017. http://www.theses.fr/2017ENAM0043/document.

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Les thermoplastiques hautes performances poly(éther-cétone-cétone) (PEKK) sont actuellement étudiés avec un grand intérêt dans l’industrie aéronautique comme matrice pour la fabrication de pièces de structure composites renforcées par des fibres de carbone. En effet, les composites thermoplastiques PEKK ont l’avantage d’être consolidables hors autoclave et ont des températures de mise en œuvre plus faibles que les composites PEEK.L’objectif de cette étude est de comprendre et prédire l’évolution des propriétés mécaniques des composites PEKK suivant le cycle thermique de mise en œuvre pour déterminer les paramètres de mise en œuvre optimaux pour la fabrication des pièces composites PEKK concernant les temps de mise en œuvre et les performances mécaniques finales.Une première partie traite de la modélisation des cinétiques de cristallisation des matrices PEKK ainsi que l’influence de la cristallinité et des morphologies cristallines sur les propriétés mécaniques des matrices PEKK. Une deuxième partie se concentre sur les modifications macromoléculaires des matrices PEKK pour des hautes températures de mise en œuvre sous air et sous azote et leurs impacts sur la cristallisation et les performances mécaniques des matrices PEKK. Enfin une dernière partie présente l’influence des fibres de carbones sur les morphologies cristallines et les cinétiques de cristallisation, la fabrication de composites PEKK unidirectionnels et tissés à ± 45° sous presse et sous autoclave et enfin l’impact de la cristallinité et des morphologies cristallines sur les performances mécaniques finales des composites PEKK
Poly(ether-ketone-ketone) (PEKK) high performance thermoplastics are currently studied with a great interest by the aeronautic industry as matrix for carbon fiber reinforced structural parts. In fact, PEKK composites can be consolidated out of autoclave and they have lower processing temperatures than PEEK composites.The aim of the study was to investigate and predict the evolution of PEKK composite mechanical properties depending on the processing thermal cycle to determine the best processing parameters for PEKK composite part manufacturing regarding processing times and final mechanical performances.A first part investigates the crystallization kinetics modelling of PEKK matrices and the influence of crystallinity and crystalline morphologies on PEKK matrix mechanical properties. A second part focuses on the macromolecular modifications of PEKK matrices at high processing temperatures under air and nitrogen and their impact on PEKK matrices crystallization and mechanical properties. A last part presents the influence of carbon fibers on crystalline morphologies and crystallization kinetics, the manufacturing of unidirectional and ± 45° PEKK composites under press and autoclave and finally the impact of crystallinity and crystalline morphologies on PEKK composite mechanical properties

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Brown, Elvie Escorro. "Bacterial cellulose/thermoplastic polymer nanocomposites." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Thesis/Spring2007/e_brown_050207.pdf.

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Wagner, Philip Cameron. "On-line consolidation of thermoplastic towpreg composites in filament winding." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/17235.

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Wilkinson, Steven P. "Toughened bismaleimides, their carbon fiber composites and interphase evaluation studies." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/38782.

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The concept of employing engineering thermoplastics as toughness modifiers for Bismaleimide resins was utilized to improve the fracture toughness properties of these important materials, which have applications as matrix resins for high performance composites. Modifier molecular weight, end group functionality, backbone structure and weight percent incorporation were all studied with respect to their influence on Kj, fracture toughness properties. Increases in fracture toughness were created with thermoplastic oligomers without sacrificing high temperature properties and desirable hot-melt processing conditions. Investigations were also made to study the morphological features that develop within these modified thermosets and their resistance to specific environments. In addition, unidirectional carbon fiber composites were prepared and their mode | and II strain energy release rates measured. Respectable increases in the interlaminar fracture toughness were obtained, 15 and 20 percent by weight loadings of maleimide terminated polysulfone modifiers yielded Gj, values of 489425 and 734+10 Jim2 respectively, a substantial improvement over the control value of 359+17 J/im2. Laminates were prepared using carbon fibers that had been investigated in terms of their surface energies using Inverse Gas Chromatography. It was illustrated how this technique could distinguish between the acid-base properties of fibers possessing different degrees of proprietary surface treatments. Fiber composites containing both contrasting and subtle changes at the fiber-matrix interphase were prepared and their mechanical properties evaluated using a variety of test methods. Dramatic increases in laminate properties were measured for composites possessing contrasting interphases. Furthermore, the mode II fracture toughness test was sensitive to interphase differences; however, the mode | fracture toughness test was not. Specimens subjected to the new Continuous Ball Indentation test method (mesoindentation) were compared with single fiber micro-indentation test results. Differences were detected in composites prepared using untreated and surface treated fibers. The new method was also sensitive to changes in matrix ductility. Certain anomalies that were noted to be surprising from micro-indentation measurements were not present in the meso-indentation test results. These observations brought to light certain limitations found within the micro-indentation test, but further supported the new test method as a potential technique for fiber-matrix interphase evaluation.
Ph. D.

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Chapman, Benjamin James. "Continuous fibre reinforced thermoplastic pipes." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285377.

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Rogers, Dan T. "A gasless method of spraying thermoplastic resins /." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd1120.pdf.

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James, Darryl L. "Thermal analysis of the continuous filament winding process." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/16078.

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36

Shipton, Paul David. "The compounding of short fibre reinforced thermoplastic composites." Thesis, Brunel University, 1988. http://bura.brunel.ac.uk/handle/2438/5788.

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It is generally accepted that the mechanical properties of short fibre reinforced thermoplastics do not correspond with the high mechanical properties of fibres used to reinforce them. A study is made into the methods of compounding reinforcing fibres into thermoplastics to produce short fibre reinforced thermoplastics of enhanced properties. The initial method chosen for investigation is the twin screw extrusion compounding process. Variables such as fibre feeding arrangement and extrusion screw design are found to be factors influencing the properties of carbon and glass reinforced nylon 6,6. Use is made of computer programs to predict properties, assess compound quality and estimate fibre-matrix bond strength. Investigations indicate that the presence of reinforcing fibres with enhanced lengths does not result in the predicted property increases. The reasons for this shortfall are believed to lie in unfavourable fibre orientation in injection mouldings and the reduced strain to break of these materials. Short Kevlar reinforced thermoplastics are compounded and their mechanical properties assessed. The reasons for the poor mechanical properties for these materials are identified as a poor bond strength between fibre and matrix, the formation of points of weakness within the fibres by the compounding and moulding processes and the coiled arrangement of fibres present in injection mouldings. A method suitable for the routine assessment of fibre-matrix bond strength is used to examine combinations of fibre and thermoplastic matrix. A comparison is made of the values derived from this method with values calculated from stress-strain curves of injection mouldings. This allows an understanding of the nature of the fibre-matrix bond yielded by compounding and injection moulding steps. A description is given of a novel method designed to overcome the limitations of conventional compounding routes to produce long fibre reinforced injection moulding feedstock. Further work is necessary before this method is a feasible production technique.

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Fortin, Gabriel Yves. "Process-induced shape distortions in aerospace thermoplastic composites." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58020.

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Thermoplastic composite materials are of great interest in aerospace structures due to their potential for shorter manufacturing cycle times, high production rates, and their ability to be re-heated and shaped multiple times. Thermoplastic resins offer many new possibilities in their ease of repair, recycling, and welding capabilities. Aerospace-grade thermoplastic composites such as carbon fibre-reinforced polyether-ether-ketone (PEEK) are processed well above their melting point at temperatures as high as 390ºC to allow proper forming and consolidation of the material to take place. During subsequent cool-down from the process temperature, residual stresses develop due to effects of material anisotropy, part geometry, and tool-part interactions that eventually lead to undesired shape distortions in the final part geometry. As observed with thermoset composites, common distortions include spring-in of corner angles and warpage of flat sections. The tight dimensional tolerances required for aerospace parts demand that process-induced shape distortions be well understood in order to eliminate scrap parts and fitting problems during the assembly stage of the components. In this project, L-shape flanges with a corner designed at 90° are manufactured from aerospace-grade AS4/PEEK thermoplastic composite in a hot press using a matched-die tooling configuration. A thermoforming technique is employed that involves heating previously-manufactured flat panels of the material to the processing temperature prior to transfer and consolidation within a relatively cold tool held at constant load and temperature. L-shape flanges consisting of a quasi-isotropic layup of unidirectional plies as well as short randomly-oriented strands of AS4/PEEK are thermoformed at 105°C, 215°C, and 290°C. Spring-in angles of the manufactured parts are quantified using a coordinate measuring machine and the results are compared with predictions from the Nelson-Cairns expression based on material thermal expansion anisotropy. The spring-in angles are also evaluated against measurements of change in part corner angle as a function of temperature due to thermo-elastic effects during heat-up from ambient temperature in a quasi-isotropic and ROS part. The parts are further assessed in terms of thickness measurements, surface quality observations, cross-section optical microscopy, and mechanical strength testing.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

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38

Doroudiani, Saeed. "Microcellular wood-fibre thermoplastic composites, processing-structure-properties." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq41016.pdf.

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Wade, Graham Andrew. "Characterisation of adhesively bonded, plasma treated, thermoplastic composites." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399089.

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Garkhail, Sanjeev Kumar. "Composites based on natural fibres and thermoplastic matrices." Thesis, Queen Mary, University of London, 2002. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1700.

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This thesis examines the possibility of reinforcing thermoplastic matrices, notably polypropylene (PP) and polyhydroxyalkanoates (PHAs), by (a vegetable fibre) flax. An effort is made to enhance/optimise the mechanical properties of flax, PP composites through a micromechanical and macromechanical study. The fibrc'matrix interface is modified via chemical modifications as well as modifications in processing parameters (transcrystallinity). Effects of parameters like fibre length, fibre volume fraction and fibre-matrix interface modification on the mechanical properties of long flax fibre reinforced PP composites (compression moulded) as well as short flax fibre based composites (injection moulded) are studied. In order to get a better insight in the importance of these different parameters for the optimisation of composite performance, the experimental results are compared with model predictions using micromechanical models for random short-fibre-reinforced composites. For the injection moulded composites, different compounding routes are used and compared. The moisture resistance (pick-up and diffusivity) as well as dimensional stability (swelling) of natural fibre mat reinforced thermoplastics (NMTs), based on different kinds of flax fibres and PPs, are studied. The effects of a novel fibre upgrading method for flax fibres (DuralinTM) on the moisture pick-up and residual tensile properties of NMT composites are explored. Biodegradable composites based on flax fibre and PHAs are analysed. It is observed that addition of (cheap) flax fibre to polyhydroxybutyrate (PHB) could be advantageous as far as cost-performance of biopolymer composites is concerned. especially for stiffness critical applications. Mechanical properties of `biocomposites' manufactured through different routes (i. e. injection moulding and compression moulding) are compared. Addition of cheap flax fibres to an expensive and brittle PI IA composite leads to enhanced toughness of the composites. Abstract A life cycle assessment (LCA) study on glass-fibre-mat-reinforced-thermoplastic (GMT) and NMT manufactured by a current production method for thermoplastic prepregs followed by compression moulding into an automotive and non-automotive part is carried out.

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Umberger, Pierce David. "Characterization and Response of Thermoplastic Composites and Constituents." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/33574.

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The research presented herein is an effort to support computational modeling of ultra-high molecular weight polyethylene (UHMWPE) composites. An effort is made to characterize the composites and their constituents. UHMWPE, as a polymer, is time and temperature dependent. Using time-temperature superposition (tTSP), the constituent properties are studied as a function of strain rate. Properties that are believed to be significant are fiber tensile properties as a function of strain rate, as well as the through-thickness shear behavior of composite laminates. Obtaining fiber properties proved to be a challenge. The high strength and low surface energy of the fibers makes gripping specimens difficult. Several different methods of fixturing and gripping are investigated, eventually leading to a combination of friction and adhesion approaches where a fiber was wrapped on an adhesive coated cardboard mandrel and then gripped in the test fixture. Fiber strength is estimated using tTSP to equivalent strain rates approaching 10^6 sec^-1. Punch-shear testing of UHMWPE laminates is conducted at quasi-static strain rates and the dependence of the results on thickness and test geometry is investigated.
Master of Science

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Björkman, Linnéa, and Alexandra Lidholm. "Thermoplastic composites in aerosructure industries : An evaluation report." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209942.

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There has been a high development of advanced composites with matrix systems of thermoset polymers in the aerostructure industry, but these thermosets can cause problems. Therefore, the aim of this project is to evaluate matrix systems made of thermoplastics, which has been done by theoretical studies. Thermoplastic composites have been developed lately because of a potential reduced costs and weight of the aircraft. Three thermoplastic polymers were chosen to be further investigated, based on process temperature requirements with a range of 200°C, 300°C and 400°C, from Saab Aerostructures. Thermoplastic composites have a higher price range because of their advanced properties. It is difficult to reduce the price of raw materials and therefore it is considered easier to lower the costs in manufacturing processes. The result of the chosen thermoplastics was that Polyether-ether-ketone (PEEK) is a suitable material in composite matrices within the range of 400°C, because of their unusual high melt temperature and low glass transition temperature. For the temperature range of 300°C, Polyetherimide (PEI) was considered as a suitable polymer because of excellent properties similar to PEEK, but with a lower compressive strength. Polycarbonate (PC) was chosen for the temperature range of 200°C because of advantages like great impact strength and thermal stability.

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Villechevrolle, Viviane Louise. "Polymer blends for multi-extruded wood-thermoplastic composites." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Thesis/Fall2008/v_villechevrolle_121008.pdf.

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Thesis (M.S. in civil engineering)--Washington State University, December 2008.
Title from PDF title page (viewed on Mar. 2, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references.

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Subramaniyam, S. "Structure and properties of nanoparticulate mica- thermoplastic composites." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2005. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2459.

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Saujanya, C. "Polymer mediated growth and morphology in thermoplastic composites." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1998. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3398.

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Brunnacker, Lena. "Short Carbon Fiber-Reinforced Thermoplastic Composites for Jet Engine Components." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76733.

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State-of-the-art aircraft engine manufactures aim to reduce theirenvironmental impact steadily. Thereby they attempt to increase engineefficiency, use new renewable fuel sources and most importantly aim toreduce component weight. While Titanium, Aluminum and continuousfiber reinforced thermosetting composites and superalloys prevail in thecurrent material selection, the present work desires to raise awareness fora novel group of materials; short carbon fiber reinforced thermoplasticcomposites (SCFRTPs). In this kind of composite short fibers givedimensional stability and strength while the thermoplastic matrix ensuresthe physical properties, even at temperatures up to 300°C.Even though in some applications these materials offer great potential tosave weight and cost, it is not clear if their properties suffice to be used indemanding areas of the aero engine and if they are still able provide costand weight reductions there.The present work therefore investigated potential aero-engine componentsthat could be replaced by SCFRTPs. With literature, manufacturer data andmaterial and process modelling approaches, it is shown that SCFRTPsmechanical and physical properties suffice for the selected component.Further it is shown that cost reductions up to 77% and weight savings upto 67% compared to the Ti-6Al-4V baseline component are possible.

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Chang, Yeou Shin. "The effect of the interphase/interface region on creep and creep rupture of thermoplastic composites." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-170854/.

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Bradley, Jurron. "Consolidation of fiber-reinforced composities with thermoplastic matrices." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/11303.

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Barber, Asa H. "Fibre-matrix interactions in model glass fibre-thermoplastic composities." Thesis, Imperial College London, 2002. http://hdl.handle.net/10044/1/11822.

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Yoon, Tae-Ho. "Adhesion study of thermoplastic polymides with Ti-6Al-4V alloy and PEEK-graphite composites." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-134525/.

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Dissertations / Theses on the topic 'Thermoplastic composites'

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