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Hygrothermal ageing of CSM-laminates during water immersion-an acousto-ultrasonic study
place through crack-tip blunting caused by localized shear yielding induced by the presence of rubber particles.
Dynamic mechanical, electrical and magnetic properties of ferrite-filled styrene-isoprenestyrene Saini, D.R., Nadkarmi, V.M.. Grover, P.D. and Nigam, K.D.P. Journal of Materials Science Vol 21 (1986) pp 3710-3716 The dynamic mechanical, electrical and magnetic properties of styrene-isoprene-styrene (SIS) block copolymer filled with barium ferrite (volume fractions of 75-88 wt %) have been reported. The storage modulus of the composite was found to increase considerably while the damping characteristics remained unaltered, even at ferrite loadings of 85 wt %, and the electrical insulation characteristics were also retained. It was found that the toughness and hardness could bc correlated to tan~ and storage modulus respectively. The use of titanote coupling agents for surface treatment of the ferrites improved the magnetic properties, due possibly to improved filler dispersion. The dynamic moduli of particulate-filled polymers as defined by the concept of interphase Sideridis, E. Composites Science and Technology Vo127 No 4 (1986) pp 305-332 A simplified theoretical approach is presented for the prediction of the dynamic moduli of particulate-filled polymers which takes into account the interphase between filler and matrix which possesses different physicochemical properties from those of the constituent phases. Calculated values were compared with results of tests on a cold-setting epoxy resin filled with iron particles. Effect of volume fraction of dispersed rubbery phase on the toughness of rubber-toughened epoxy polymers Kinloch, A.J. and Hunston, D.L. Journal of Materials Science Letters Vol 5 No 12 (1986) pp 1207-1209 The toughness of an epoxy may be improved by the presence of a dispersion of second phase rubbery particles. The initial results on the eft'oct of microstructural features on the toughness of an epoxy resin (diglycidyl ether of bisphenol A) cured with piperidine are presented. The rubber used was a carboxylterminated, random copolymer of butadiene and acrylonitrile. It is found that increasing the volume fraction of the rubbery phase does increase fracture toughness but the amount of toughening depends on test conditions such as the test rate and the test temperature. Effects of material constitutions on the strength of fiber reinforced plastic gears Ikegami, K.. Kikushima, K. and Shiratori, E. Composites Science and Technology Vol 27 No 1 (1986) pp 43-61 The strength of fibre-reinforced plastic gears was analytically and experimentally investigated. Glass or carbon roving cloths were used in the gear tooth surfaces as reinforcing fibres. while chopped glass or carbon fibres were used in the core region: epoxy resin was used throughout as matrix material. A stress analysis using a finite element method was performed for the gears subjected to bending loads. From the results, the most effective reinforcing method is discussed. Hygrothermal ageing of CSM-laminates during water immersion--an acousto-ultrasonic study Phani. K.K. and Bose, N.R. Journal of Materials Science Vol 21 (1986) pp 3633-3637 Random mat E-glass/polyester composites
COMPOSITES. APRIL 1987
were fabricated and their acoustic-ultrasonic stress wave factor (SWF) was monitored before, and at regular intervals after, ageing in distilled water at temperatures of 100°C, 42°C and 60°C. The room temperature flexural strength of aged samples was also measured at regular intervals. The authors conclude that the SWF is a sensitive indicator of strength reduction due to hygrothermal ageing and that. for a given system, SWF readings may be used to estimate the strength from data generated under accelerated conditions.
Interface strength effects on the compressiveflexurai/shear failure mode transition of composites subjected to four point bending Shih, G.C. and Ebert, L.J. Journal of Materials Science Vo121 (1986) pp 3957-3965 The modes of failure of unidirectional glass/ epoxy composites (in four-point bend) with different interface conditions have been investigated experimentally and analytically. Wang's microbuckling model has been extended to derive failure mode transition diagrams for composites with different interface strengths. It is suggested that the failure mode (flexural compressive or shear) may serve as a rule of thumb for estimating the interface condition for a new system of composites. The reinforced reaction-injection moulding revolution English, L.K. Materials Engineering (October 1986) pp 39-43 This article, on novel reaction injection moulding (RIM) systems, also described a new system introduced by Dow Chemicals which combines low viscosity RIM components with pro-placed mat reinforcements to provide long fibre composite properties. Sliding and abrasive wear of short glass-fibre reinforced PTFE-composites Voss, H. and Friedrich, K. Journal of Materials Science Letters Vol 5 No 11 (1986) pp 1111-1114 The influence of glass fibre additions on the wear properties of PTFE has been investigated. Four materials were used -- neat resin and three grades containing 13, 22, and 36% by volume of glass fibres of diameter approximately 10 p.m and length < 100 p.m. Wear tests were carried out against smooth steel rings and two grades of abrasive paper (abrasive particle sizes of 7 pm and 70 btm). Sliding speed (v) was found to be more detrimental to wear rate than pressure (P) if the (PV) factor is kept constant. SEM investigations were carried out to establish the wear mechanisms occurring. A rule-ofmixtures equation was used to relate wear rate with fibre fraction, Some aspects of shock consolidation of polymeric, PVC-metallic and PVC-silica powder mixtures Abousree Hegazy, A. and Blasynski, T.Z. Journal of Materials" Science Vol 21 (1986) pp 4262-4268 The explosive compaction technique and the effects of shock consolidation on PVC and mixtures of PVC with 304 stainless steel, iron powder and silica have been investigated. The properties discussed include morphology, fracture surfaces, the degree of densification and compressive strength. It is concluded that shock consolidation affords a means of producing new composite materials having well-defined and well-bonded structures which are of potential industrial interest. Static fatigue and time to failure predictions of particulate filled epoxide resin composites
Beer. H.R., Kaiser, T., Maloney. A.C. and Kaush. H.H. Journal of Materials Science Vo121 (1986) pp 3661-3667 The applicability of lifetime prediction techniques to two types of epoxide resins with high volume fractions (up to 60%) of particulate filler (alumina flour and silane-treated glass beads and silica flour) has been examined. The stress/ strain and static fatigue behaviour was studied at various temperatures. It was found that the composites were subject to static fatigue and that the static fatigue strength (under constant load) can be predicted on the basis of a fracture mechanics crack growth model. Crack growth measurements were determined by double torsion tests and constant stressing-rate experiments. Both procedures lead to nearly equivalent predictions of static fatigue which compare well with laboratory, static fatigue data from room temperature almost up to the glass transition temperature.
Stress corrosion cracking and its propagation in aligned short fibre composites Hsu, P.-L., You, S.-S. and C hou, T.-W.Journal of Materials Science Vol 21 (1986) pp 3703-3709 The crack propagation modes and service lives of aligned short fibre composites (glass, carbon and E-glass-carbon hybrid reinforced composites) have been examined in both air and 1N H2SO 4 environments. Crack growth characteristics were determined using compact tension specimens. Curves of crack growth vs loading time to failure (K I vs tf) are used successfully to evaluate the degradation of crack resistance due to stress corrosion and to predict the service life of a composite containing cracks. It was found that pro-immersion has significant effects on the K I vs tf curve and crack arrest of hybrid composites. Various crack propagation models are proposed to describe the different fracture modes observed. Sunhemp fibre-reinforced polyester. Part 1. Analysis of tensile and impact properties Sandi, A.R., Prasad, S.V. and Rohatgi. P.K. Journal of Materials Science Vol 21 (1986) pp 4299-4304 The properties of unidirectional. 'continuous' sunhemp/polyester composites have been evaluated. It was found that the tensile strength incrcascd linearly with increase in Vr (volume fraction) according to the rule of mixtures, and that the Izod impact strength also increased linearly with Vf. The toughness increase is discussed in terms of fibre pull-out and interface fracture. Temperature dependent mechanical behaviour of PI and PES resins used at matrices for short fibre reinforced laminates Schulte, K., Friedrich, K. and Horstenkemp, G. Journal of Materials Science Vol 21 (1986) pp 3561-3570 The mechanical behaviour of polyimide (PI) and polyethersulphone (PES) matrices, and their aligned, short fibre-reinforced corn posites, has been investigated at temperatures of 21°C, 100°C and 180°C. The PES matrix was found to have the highest fracture strain and fracture stress at room temperature but the poorest wettability. A rapid decrease in fracture stress with temperature was observed (69 MPa at 2 I°C to ~10 MPa at 18(/°C). The PI matrix had the higher modulus at 21°C ( ~ 4 9 GPa): this value was halved at 180°C (but was higher than that of PES at 180°C). Aligned short fibre composites including those made with an epoxy matrix were tested in both the fibre direction and at °AF to it. It was generally concluded that the properties of the PES matrix are not fully
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Dynamic mechanical, electrical and magnetic properties of ferrite-filled styrene-isoprenestyrene Saini, D.R., Nadkarmi, V.M.. Grover, P.D. and Nigam, K.D.P. Journal of Materials Science Vol 21 (1986) pp 3710-3716 The dynamic mechanical, electrical and magnetic properties of styrene-isoprene-styrene (SIS) block copolymer filled with barium ferrite (volume fractions of 75-88 wt %) have been reported. The storage modulus of the composite was found to increase considerably while the damping characteristics remained unaltered, even at ferrite loadings of 85 wt %, and the electrical insulation characteristics were also retained. It was found that the toughness and hardness could bc correlated to tan~ and storage modulus respectively. The use of titanote coupling agents for surface treatment of the ferrites improved the magnetic properties, due possibly to improved filler dispersion. The dynamic moduli of particulate-filled polymers as defined by the concept of interphase Sideridis, E. Composites Science and Technology Vo127 No 4 (1986) pp 305-332 A simplified theoretical approach is presented for the prediction of the dynamic moduli of particulate-filled polymers which takes into account the interphase between filler and matrix which possesses different physicochemical properties from those of the constituent phases. Calculated values were compared with results of tests on a cold-setting epoxy resin filled with iron particles. Effect of volume fraction of dispersed rubbery phase on the toughness of rubber-toughened epoxy polymers Kinloch, A.J. and Hunston, D.L. Journal of Materials Science Letters Vol 5 No 12 (1986) pp 1207-1209 The toughness of an epoxy may be improved by the presence of a dispersion of second phase rubbery particles. The initial results on the eft'oct of microstructural features on the toughness of an epoxy resin (diglycidyl ether of bisphenol A) cured with piperidine are presented. The rubber used was a carboxylterminated, random copolymer of butadiene and acrylonitrile. It is found that increasing the volume fraction of the rubbery phase does increase fracture toughness but the amount of toughening depends on test conditions such as the test rate and the test temperature. Effects of material constitutions on the strength of fiber reinforced plastic gears Ikegami, K.. Kikushima, K. and Shiratori, E. Composites Science and Technology Vol 27 No 1 (1986) pp 43-61 The strength of fibre-reinforced plastic gears was analytically and experimentally investigated. Glass or carbon roving cloths were used in the gear tooth surfaces as reinforcing fibres. while chopped glass or carbon fibres were used in the core region: epoxy resin was used throughout as matrix material. A stress analysis using a finite element method was performed for the gears subjected to bending loads. From the results, the most effective reinforcing method is discussed. Hygrothermal ageing of CSM-laminates during water immersion--an acousto-ultrasonic study Phani. K.K. and Bose, N.R. Journal of Materials Science Vol 21 (1986) pp 3633-3637 Random mat E-glass/polyester composites
COMPOSITES. APRIL 1987
were fabricated and their acoustic-ultrasonic stress wave factor (SWF) was monitored before, and at regular intervals after, ageing in distilled water at temperatures of 100°C, 42°C and 60°C. The room temperature flexural strength of aged samples was also measured at regular intervals. The authors conclude that the SWF is a sensitive indicator of strength reduction due to hygrothermal ageing and that. for a given system, SWF readings may be used to estimate the strength from data generated under accelerated conditions.
Interface strength effects on the compressiveflexurai/shear failure mode transition of composites subjected to four point bending Shih, G.C. and Ebert, L.J. Journal of Materials Science Vo121 (1986) pp 3957-3965 The modes of failure of unidirectional glass/ epoxy composites (in four-point bend) with different interface conditions have been investigated experimentally and analytically. Wang's microbuckling model has been extended to derive failure mode transition diagrams for composites with different interface strengths. It is suggested that the failure mode (flexural compressive or shear) may serve as a rule of thumb for estimating the interface condition for a new system of composites. The reinforced reaction-injection moulding revolution English, L.K. Materials Engineering (October 1986) pp 39-43 This article, on novel reaction injection moulding (RIM) systems, also described a new system introduced by Dow Chemicals which combines low viscosity RIM components with pro-placed mat reinforcements to provide long fibre composite properties. Sliding and abrasive wear of short glass-fibre reinforced PTFE-composites Voss, H. and Friedrich, K. Journal of Materials Science Letters Vol 5 No 11 (1986) pp 1111-1114 The influence of glass fibre additions on the wear properties of PTFE has been investigated. Four materials were used -- neat resin and three grades containing 13, 22, and 36% by volume of glass fibres of diameter approximately 10 p.m and length < 100 p.m. Wear tests were carried out against smooth steel rings and two grades of abrasive paper (abrasive particle sizes of 7 pm and 70 btm). Sliding speed (v) was found to be more detrimental to wear rate than pressure (P) if the (PV) factor is kept constant. SEM investigations were carried out to establish the wear mechanisms occurring. A rule-ofmixtures equation was used to relate wear rate with fibre fraction, Some aspects of shock consolidation of polymeric, PVC-metallic and PVC-silica powder mixtures Abousree Hegazy, A. and Blasynski, T.Z. Journal of Materials" Science Vol 21 (1986) pp 4262-4268 The explosive compaction technique and the effects of shock consolidation on PVC and mixtures of PVC with 304 stainless steel, iron powder and silica have been investigated. The properties discussed include morphology, fracture surfaces, the degree of densification and compressive strength. It is concluded that shock consolidation affords a means of producing new composite materials having well-defined and well-bonded structures which are of potential industrial interest. Static fatigue and time to failure predictions of particulate filled epoxide resin composites
Beer. H.R., Kaiser, T., Maloney. A.C. and Kaush. H.H. Journal of Materials Science Vo121 (1986) pp 3661-3667 The applicability of lifetime prediction techniques to two types of epoxide resins with high volume fractions (up to 60%) of particulate filler (alumina flour and silane-treated glass beads and silica flour) has been examined. The stress/ strain and static fatigue behaviour was studied at various temperatures. It was found that the composites were subject to static fatigue and that the static fatigue strength (under constant load) can be predicted on the basis of a fracture mechanics crack growth model. Crack growth measurements were determined by double torsion tests and constant stressing-rate experiments. Both procedures lead to nearly equivalent predictions of static fatigue which compare well with laboratory, static fatigue data from room temperature almost up to the glass transition temperature.
Stress corrosion cracking and its propagation in aligned short fibre composites Hsu, P.-L., You, S.-S. and C hou, T.-W.Journal of Materials Science Vol 21 (1986) pp 3703-3709 The crack propagation modes and service lives of aligned short fibre composites (glass, carbon and E-glass-carbon hybrid reinforced composites) have been examined in both air and 1N H2SO 4 environments. Crack growth characteristics were determined using compact tension specimens. Curves of crack growth vs loading time to failure (K I vs tf) are used successfully to evaluate the degradation of crack resistance due to stress corrosion and to predict the service life of a composite containing cracks. It was found that pro-immersion has significant effects on the K I vs tf curve and crack arrest of hybrid composites. Various crack propagation models are proposed to describe the different fracture modes observed. Sunhemp fibre-reinforced polyester. Part 1. Analysis of tensile and impact properties Sandi, A.R., Prasad, S.V. and Rohatgi. P.K. Journal of Materials Science Vol 21 (1986) pp 4299-4304 The properties of unidirectional. 'continuous' sunhemp/polyester composites have been evaluated. It was found that the tensile strength incrcascd linearly with increase in Vr (volume fraction) according to the rule of mixtures, and that the Izod impact strength also increased linearly with Vf. The toughness increase is discussed in terms of fibre pull-out and interface fracture. Temperature dependent mechanical behaviour of PI and PES resins used at matrices for short fibre reinforced laminates Schulte, K., Friedrich, K. and Horstenkemp, G. Journal of Materials Science Vol 21 (1986) pp 3561-3570 The mechanical behaviour of polyimide (PI) and polyethersulphone (PES) matrices, and their aligned, short fibre-reinforced corn posites, has been investigated at temperatures of 21°C, 100°C and 180°C. The PES matrix was found to have the highest fracture strain and fracture stress at room temperature but the poorest wettability. A rapid decrease in fracture stress with temperature was observed (69 MPa at 2 I°C to ~10 MPa at 18(/°C). The PI matrix had the higher modulus at 21°C ( ~ 4 9 GPa): this value was halved at 180°C (but was higher than that of PES at 180°C). Aligned short fibre composites including those made with an epoxy matrix were tested in both the fibre direction and at °AF to it. It was generally concluded that the properties of the PES matrix are not fully
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