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Fibre reinforced plastic (FRP) composites consist of two or more components combined to give a synergistic effect for a better performance in service. One of the phases comprises layers of fibrous material while the other phase comprises of a polymer matrix. In this project, carbon fibre pre-preg material was used. All materials contain imperfections. Materials constituents and manufacturing anomalies are the main causes of faults in FRP composites. The presence of voids in FRP composites is the most common defect. The aim of this project was to determine the influence of voids on the static and dynamic compressive properties of carbon fibre reinforced plastic (CFRP) composites. The influence of voids on fatigue life and failure behaviour were also investigated.

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Polymer composite materials, particularly glass reinforced plastics (GRP), are increasingly being used in the offshore industry and their behaviour in fire is studied using mathematical and numerical modelling. A generalised finite element method is developed to analyse the thermally induced response of a widely used GRP, consisting of polyester resin and glass fibre reinforcement. GRP panels, pipes and joins subject to hydrocarbon fires (i.e. high temperatures) are studied. One- and two-dimensional mathematical models are developed to study the fire performance of: (i) single-skinned GRP panels, (ii) twin-skinned GRP-Vermiculux sandwich panels, and (iii) thin and thick GRP joins (step panels). The models involve thermochemical decomposition of the material (pyrolysis) and include: (i) transient heat conduction, (ii) gas mass movement and internal heat convection of pyrolysis gases, (iii) mass loss and Arrhenius rate decomposition of the resin material into gases and char, and (iv) endothermicity of pyrolysis. The effect of imperfect bonding on heat transfer in sandwich panels and the accumulation of pyrolysis gases and internal pressurisation in thick step panels are also included. The models may be used with any combination of steady or time-dependent boundary conditions including temperature, radiation, chemical reactions, mass diffusion and free and forced convections. Various positions of panels, i.e. vertical, horizontal and inclined are studied. The material is assumed homogeneous and orthotropic with respect to thermal and transport properties which may vary with temperature, pore pressure and moisture. The finite element models use weighted residual approach with linear elements for one- dimensional and quadrilateral elements for two-dimensional. Non-linear terms and coefficients are evaluated explicitly using an iterative-updating method and nodal temperatures and pore pressures implicitly using Crank-Nicolson solution. The classical finite difference time stepping algorithm is used where an efficient solution is achieved using variable time step. Numerical results are presented in the form of temperature versus time, temperature versus distance, pore pressure versus distance, mass loss versus distance and moisture versus distance and compared with experimental data where available. It is shown that the decomposition of the material, endothermicity of pyrolysis and the movement of pyrolysis gases make substantial contributions towards the cooling behaviour and delaying the bum-through. The effect of gas mass movement and surface chemical reactions across the boundary layer adjacent to the fire-exposed surface is very important in introducing a theoretical boundary condition. An investigation into the effect of inclusion the variable thermal properties reveals considerable improvement in thermal predictions. Sandwich panels consisting of GRP/Vermiculux/GRP offer good thermal insulation. Thermal contact resistance at an imperfect bonding is important where an average difference of 12% can be found between the thermal responses of sandwich panels with perfect and imperfect bonding. For thin GRP step panels, a one-dimensional solution is found adequate to predict the fire resistance behaviour of the material. For thick GRP step panels, the effect of internal pressurisation coupled with temperature on the thermal response is considerable.

The study is a comparison of junior college plastics curriculums in Dallas, Tarrant, and surrounding counties and the requirements of the reinforced plastics industry in the Dallas-Fort Worth area.

Great interest has been generated in the use of natural fibres as environmentally friendly reinforcing materials in polymeric composites, which do not require high load bearing capabilities. kenaf fibres extracted from kenaf plants (hibiscus cannabinus) have been identified as an attractive option due to its production cost and the ability of the kenaf plants to grow in a variety of climatic conditions. Polypropylene (PP) has a relatively low production cost, excellent corrosion resistance, good retention of mechanical properties and less recycling challenges in comparison to other matrix systems such as thermosets. Given the individual advantages of kenaf fibre and polypropylene, kenaf reinforced polypropylene composites (kenaf/PP composites) have considerable commercial interest in the composite industry. However, limitations arise with respect to the mechanical performance and to the resistance to moisture absorption when natural fibres are used. This study focuses on the improvement of the mechanical properties (e.g. tensile, flexural, fatigue and impact properties) and the resistance to moisture absorption of kenaf reinforced polypropylene composites by means of fibre treatments (e.g. alkali and alkali-silane treatments) and the use of filler materials (e.g. functionalized multi-wall carbon nanotubes). Kenaf reinforced polypropylene composites are manufactured by a modified compression moulding using the film–stacking technique. The crux of this technique is that kenaf mats are impregnated with polypropylene powder in order achieve a uniform material distribution and to lower the manufacturing temperature, thereby preventing the thermal alteration of the composite constituents (e.g. kenaf fibres) and silano functional groups attached to the multi-wall carbon nanotubes. Fibre treatments including alkali treatments and alkali followed by silane treatments (alkali-silane) are considered in order to improve the fibre-matrix interfacial adhesion. The concentrations of the alkali solutions range from 1% to 8% in intervals of 1% by mass. Fibre contents ranging from 20% to 35% in interval of 5% by mass are considered for both kenaf and glass fibre reinforced plates. Functionalized multi-wall carbon nanotubes are used as filler material in order to improve the mechanical properties of the composite plates. The concentrations of the multiwall carbon nanotube (MWCNT) range from 0.1% to 1.25%. Mechanical test and microscopic examination results showed that alkali treatments improve the mechanical properties of kenaf/PP composites. However, the improvements due to alkali-silane treatments were found to be more significant because additional silane treatments substantially enhanced the fibrematrix interfacial adhesion. Material failures in untreated kenaf/PP composites and alkali treated kenaf/PP composites were mainly characterized by fibre pullouts, whereas in alkali-silane treated kenaf/PP composites they were characterised by fibre breakage. Alkali concentrations of 5% and 6% NaOH are found to the optimum concentrations for both alkali treatment and alkali-silane treatment. The use of functionalized MWCNTs as filler material improved furthermore the mechanical properties of kenaf/PP-MWCNT composites in comparison to those of kenaf/PP and glass/PP composites. The main contributing factors of the improvements were found to be the enhancement of the interfacial adhesion between the nanoparticles and the matrix, and also between the nanoparticles and kenaf fibres. Material failures in kenaf/PP-MWCNT composites were characterized by fibre breakage and matrix cracks. The optimum MWCNT concentrations were found to be 0.5% and 0.75%. 30% fibre contents was found to be the optimum fibre content for both kenaf/PP and kenaf/PP-MWCNT composites. Test results showed that the fibre treatments, especially alkali-silane treatment, improved the resistance to moisture absorption of the composites. Test results also showed that the manufacturing technique, which enables the manufacturing of composite plates with layers of different moisture diffusion resistances, has a significant influence on the resistance of kenaf/PP composites. The addition of multi-wall carbon nanotubes to the polypropylene matrix did not alter the moisture absorption resistance of kenaf/PP-MWCNT composites. The impregnation of kenaf and fibre glass mats with polypropylene powder significantly lowered the manufacturing temperature

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Jaime Kanarek Kornfeld. / M.S.

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