Influence of hybridisation and test geometry on the impact response of glass-fibre-reinforced laminated composites

Falling weight impact tests were carried out on glass fibre reinforced laminates and E-glass/Dyneema (high performance polyethylene fibre) hybrid laminates to determine the influence of hybridisation and test geometry on their impact responses. Tests included falling weight impact tests to determine penetration energy and experiments to determine the effect of hybrid construction on damage development. The results of these tests indicated that in order to fully utilise the potential of high performance PE fibres, they should be located on the tensile side of an impacted laminated, and that the geometrical test conditions are such that large bending deformations are allowed

Wide- and small-angle X-ray scattering studies on the deformation behaviour of poly(ethylene terephthalate)

In this study the microscopic deformation behaviour of amorphous PET during uniaxial tensile tests at room temperature was investigated by in-situ wide- and small-angle X-ray scattering using synchrotron radiation. WAXD patterns of deformed PET show a highly orientated amorphous halo and no significant crystallization was found. SAXS patterns of the slowest drawn samples show typical craze like patterns, which finally evolve in elliptically shaped patterns, indicating micro voiding. At higher draw rates the formation of fibrils is not observed and the material directly cavitates. This micro voiding phenomenon causes whitening of the deformed PET

Predicting the yield stress of polymer glasses directly from processing conditions: application to miscible systems

A previously developed model which predicts the yield stress of a polymer glass directly from processing conditions is applied to a system of miscible polymers. The selected system consists of a blend of polycarbonate with polyester and three blend compositions of increasing weight percentages polyester are investigated with respect to their aging kinetics. Based on these kinetics, the yield stress as it results form the thermal history experienced during processing is predicted and found to be in good agreement with experimental results. The parameters governing the evolution of the yield stress are shown to follow the rule of mixtures, enabling the prediction of the yield stress of any blend composition