Crystallization and mechanical properties of a thermoplastic PET reinforced with unidirectional glass fibres

The influence of processing conditions on the resulting mechanical properties of glass/PET composites has been investigated. First, we studied the anisothermal crystallization of PET with and without glass fibres, considering both thermodynamic and kinetic aspects. The main variables considered were temperature of treatment in the molten state (T(i)) and cooling rate (nu). Second, according to the results of the first part unidirectional composites were compression moulded. Short-term (dynamic and static) shear tests and long-term flexural fatigue tests were performed to characterize the effects of moulding conditions. This study demonstrates that the thermochemical history during the composite processing significantly influences the short- and long-term mechanical properties of the composite especially in the presence of shear stresses.