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The mechanical properties of chalk-filled polypropylene: A preliminary investigation
Bolted joints in sheet moulding compound (18% E-glass fibres in a polyester matrix) were studied in order to determine the effect of the joint parameters on the fatigue life. Parameters studied included edge margin/ hole diameter (e/d), specimen width/hole diameter (w/d) and the washer geometry. It was observed that e/d should be at least three in order for fatigue failure to occur in the washer and larger washer diameters lead to significantly longer fatigue lives. Fibre length distribution effects on the fracture of short fibre composites Carling, M.J. and Williams, J.G. Polymer Composites Vo111 No 6 (1990) pp 307-313 The fracture properties of three, short-fibrereinforced nylon-matrix composites were examined using three-point bend LEFM, impact testing and slow crack growth. A conventional 30% glass fibre extruded material was compared with 30 and 50% pultruded materials at various humidity levels. Little difference was found in properties for dry samples but the pultruded materials displayed enhanced toughness as the moisture content increased. This was attributed to the increased fibre length and diameter found in pultruded materials. Flexural properties and dynamic mechanical properties of glass fibre-epoxy composites Kimoto, M. Journal o f Materials Science Vol 25 No 7 (1990) pp 3327-3332 Dynamic mechanical and flexural properties of glass fibre/epoxy composites, fabricated using two different coupling agents, were measured above room temperature. Temperature, strain rate and the surface treatment were all found to affect the fracture behaviour of the composite. The correlation between the loss modulus and the flexural properties is also considered. Fracture mechanisms in carbon fibre reinforced poly(ether ether ketone). II: material variables Whine, P.J., Brew, B., Duckett, R.A. and Ward, I.M. Composites Science and Technology Vo140 No 1 (1991) pp 47-67 The effects of polymer molecular weight, interfacial strength and volume fraction of fibre upon the fracture behaviour of unidirectional carbon fibre/PEEK composites were considered in this paper. The double cantilever beam geometry was used with cracks usually propagated parallel to individual laminates, i.e., interlaminar fractures. The link between matrix ductility and fracture behaviour was investigated, with the highest toughness being found with the high molecular weight matrix composite. Composites treated to give low fibre/matrix adhesion showed a reduction in toughness however good crack stability. Grafting kinetics of poly(methyl methacrylate) on to mieroparticulate silica Boven, G., Oosterling, M,L.C.M., Challa, G. and Schouten, A.J. Polymer Vo131 No 12 (1990) pp 2377-2383 For the purpose of increasing the adhesion between thermoplastic polymers and fillers, the grafting of poly(methyl methacrylate) on to microparticulate silica was investigated. A radical initiator was immobilized by an amide bond formed between an amine-containing silane coupling agent on the silica and 4,4'azobis(4-cyano-pentanoic acid). Grafting on
to the silica seemed to cause some destabilization of the initiator. The kinetics of the grafting are greatly affected by the Trommsdorf effect. This leads to higher molecular ffe~ghfs bfgrafted and non-grafted polymer and hence to a high load on the silica surface. Highly filled particulate composites enhancement of performances by using compound coupling agents Yu, X.D., Malinconico, M. and Martuscelli, E. Journal of Materials Science Vol 25 No 7 (1990) pp 3255-3261 Two coupling agents have been used to increase adhesion in composites containing silica particles in polyester and epoxy resins. Filler contents of up to 90 wt% have been used. Mechanical properties were measured using a three-point bend test and increased strength and toughness were observed when the correct type of coupling agent was used to form a link between the filler and the matrix, Adhesion between the matrix and the filler was observed by SEM of the fracture surfaces, leading to a qualitative relationship between the increased adhesion and strength. Identification of factors affecting single filament pull-out test results Penn, L.S. and Chou, C.T. Journal o f Composites Technology and Research Vo112 No 3 (1990) pp 164-171 The origin of scatter was investigated for single fibre pull-out tests using plots of pullout load vs. embedded length on Kevlar/ epoxy samples. Scatter was found to be due to the size variation of the original crack and, to a lesser extent, to the variation in fibre surface energy. Residual stress, which reduced the pull-out load, was observed to displace the data to the right. An integrated methodology for optimizing the passive damping of composite structures Saravanos, D.A. and Chamis, C.C. Polymer Composites Vo111 No 6 (1990) pp 328-336 Duc to their heterogeneity and viscoelastic matrix, polymer-matrix composites offer superior vibration and damping performance compared with most metals. A method is presented which optimizes passive damping for laminated composites taking into account structural factors and micromechanics (fibre volume fraction, ply angle, etc.). The method is applied to composite beam and cylindrical shell examples. Interface morphology of carbon fibre/PEEK composites Saicllo, S., Kenny, J. and Nicolais, L. Journal o f Materials Science Vol 25 No 8 (1990) pp 3493-3496 Four samples of poly-ether-ether-ketone/ carbon fibre composites with different degrees of crystallinity were obtained by isothermally heating an amorphous composite at various temperatures. A semicrystalline composite fabricated by melt crystallization was also used. Fracture surfaces were examined by SEM. The melt-crystallized matrix showed the highest level of interfacial adhesion. Low-temperature thermal expansion of PEEK, HTA and some of their composites reinforced with carbon fibres Gaitande, J.M. and Lowson, M.V. Composites Science and Technology Vol 40 No 1 (1991) pp 69-85
Thermal expansion characteristics of poly(ether ether ketone), a modification of poly(ether sulphone) and carbon fibre-reinforced composites of these polymers were measured from -153 to 27°C using a cryogenic push-rod dilatometer. Agreement was found with other available results within experimental scatter. Multidirectional composites were also tested and qualitatively analysed with the specimen size being specifically discussed. The longitudinal and transverse coefficients of thermal expansion of Hercules AS4 fibre were also calculated. Measurement of the adhesion of poly(ether block amide) to E-glass by single filament fragmentation Merle, G. and Xie, M. Composites Science and Technology Vo140 No I (1991) pp 19-30 The single filament fragmentation test was used to study the adhesion between E-glass fibre and thermoplastic elastomer poly(ether block amide). Matrix polymers with ratios of poly(oxytetramethylene) to polyamide 12 between 77:23 and 20:80 were used. Fibres were either heat-cleaned or sized with A1100 silane coupling agent. Comparison of the shear strength of the matrix with values calculated from models for the interracial shear strength showed the interface to be elastic and weaker than the matrix. The coupling agent was shown to enhance the adhesion as a result of its affinity for the amine groups in the polymer matrix. Measurement of Gk and Gitc in carbon/epoxy composites Davies, P., Moulin, C. and Kausch, H.H. Composites Science and Technology Vol 37 No 3 (1990) pp 193-20,5 Unidirectional carbon/epoxy double cantilever beam, end-notched flexure and endloaded split specimens were tested to give values for G1¢ and Giic at crack initiation and propagation. A 10-laboratory round-robin exercise was organized by the Polymer and Composite Task Group of the European Group on Fracture (EGF) to test the reproducibility from one lab to another. These results were discussed, along with the influence of defect type and specimen geometry on the values of delamination resistance of this material. The mechanical properties of chalk-filled polypropylene: a prefiminary investigation Vollenberg, P.H.T. and Heikens, D. Journal o f Materials Science Vol 25 No 7 (1990) pp 3089-3095 The mechanical properties of polypropylene containing particulate chalk (0 to 25 vol%) were investigated to highlight points for further research. A range of particle sizes were used from 3.5 to 130 ~tm and an adhesion promoter was applied to the chalk filler in some cases. Tensile and notched impact tests were carried out and SEM was used to observe microdeformation mechanisms. Qualitative explanations of the relationship between the two sets of observations are offered. Mechanical properties of weft knit glass fibre/ polyester laminates Rudd, C.D., Owen, M.J. and Middleton, V. Composites Science and Technology Vol 37 No 3 (1990) pp 261-277 An investigation of fibre configuratons produced in weft knitting and the mechanical
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to the silica seemed to cause some destabilization of the initiator. The kinetics of the grafting are greatly affected by the Trommsdorf effect. This leads to higher molecular ffe~ghfs bfgrafted and non-grafted polymer and hence to a high load on the silica surface. Highly filled particulate composites enhancement of performances by using compound coupling agents Yu, X.D., Malinconico, M. and Martuscelli, E. Journal of Materials Science Vol 25 No 7 (1990) pp 3255-3261 Two coupling agents have been used to increase adhesion in composites containing silica particles in polyester and epoxy resins. Filler contents of up to 90 wt% have been used. Mechanical properties were measured using a three-point bend test and increased strength and toughness were observed when the correct type of coupling agent was used to form a link between the filler and the matrix, Adhesion between the matrix and the filler was observed by SEM of the fracture surfaces, leading to a qualitative relationship between the increased adhesion and strength. Identification of factors affecting single filament pull-out test results Penn, L.S. and Chou, C.T. Journal o f Composites Technology and Research Vo112 No 3 (1990) pp 164-171 The origin of scatter was investigated for single fibre pull-out tests using plots of pullout load vs. embedded length on Kevlar/ epoxy samples. Scatter was found to be due to the size variation of the original crack and, to a lesser extent, to the variation in fibre surface energy. Residual stress, which reduced the pull-out load, was observed to displace the data to the right. An integrated methodology for optimizing the passive damping of composite structures Saravanos, D.A. and Chamis, C.C. Polymer Composites Vo111 No 6 (1990) pp 328-336 Duc to their heterogeneity and viscoelastic matrix, polymer-matrix composites offer superior vibration and damping performance compared with most metals. A method is presented which optimizes passive damping for laminated composites taking into account structural factors and micromechanics (fibre volume fraction, ply angle, etc.). The method is applied to composite beam and cylindrical shell examples. Interface morphology of carbon fibre/PEEK composites Saicllo, S., Kenny, J. and Nicolais, L. Journal o f Materials Science Vol 25 No 8 (1990) pp 3493-3496 Four samples of poly-ether-ether-ketone/ carbon fibre composites with different degrees of crystallinity were obtained by isothermally heating an amorphous composite at various temperatures. A semicrystalline composite fabricated by melt crystallization was also used. Fracture surfaces were examined by SEM. The melt-crystallized matrix showed the highest level of interfacial adhesion. Low-temperature thermal expansion of PEEK, HTA and some of their composites reinforced with carbon fibres Gaitande, J.M. and Lowson, M.V. Composites Science and Technology Vol 40 No 1 (1991) pp 69-85
Thermal expansion characteristics of poly(ether ether ketone), a modification of poly(ether sulphone) and carbon fibre-reinforced composites of these polymers were measured from -153 to 27°C using a cryogenic push-rod dilatometer. Agreement was found with other available results within experimental scatter. Multidirectional composites were also tested and qualitatively analysed with the specimen size being specifically discussed. The longitudinal and transverse coefficients of thermal expansion of Hercules AS4 fibre were also calculated. Measurement of the adhesion of poly(ether block amide) to E-glass by single filament fragmentation Merle, G. and Xie, M. Composites Science and Technology Vo140 No I (1991) pp 19-30 The single filament fragmentation test was used to study the adhesion between E-glass fibre and thermoplastic elastomer poly(ether block amide). Matrix polymers with ratios of poly(oxytetramethylene) to polyamide 12 between 77:23 and 20:80 were used. Fibres were either heat-cleaned or sized with A1100 silane coupling agent. Comparison of the shear strength of the matrix with values calculated from models for the interracial shear strength showed the interface to be elastic and weaker than the matrix. The coupling agent was shown to enhance the adhesion as a result of its affinity for the amine groups in the polymer matrix. Measurement of Gk and Gitc in carbon/epoxy composites Davies, P., Moulin, C. and Kausch, H.H. Composites Science and Technology Vol 37 No 3 (1990) pp 193-20,5 Unidirectional carbon/epoxy double cantilever beam, end-notched flexure and endloaded split specimens were tested to give values for G1¢ and Giic at crack initiation and propagation. A 10-laboratory round-robin exercise was organized by the Polymer and Composite Task Group of the European Group on Fracture (EGF) to test the reproducibility from one lab to another. These results were discussed, along with the influence of defect type and specimen geometry on the values of delamination resistance of this material. The mechanical properties of chalk-filled polypropylene: a prefiminary investigation Vollenberg, P.H.T. and Heikens, D. Journal o f Materials Science Vol 25 No 7 (1990) pp 3089-3095 The mechanical properties of polypropylene containing particulate chalk (0 to 25 vol%) were investigated to highlight points for further research. A range of particle sizes were used from 3.5 to 130 ~tm and an adhesion promoter was applied to the chalk filler in some cases. Tensile and notched impact tests were carried out and SEM was used to observe microdeformation mechanisms. Qualitative explanations of the relationship between the two sets of observations are offered. Mechanical properties of weft knit glass fibre/ polyester laminates Rudd, C.D., Owen, M.J. and Middleton, V. Composites Science and Technology Vol 37 No 3 (1990) pp 261-277 An investigation of fibre configuratons produced in weft knitting and the mechanical
COMPOSITES. MAY 1991
251