THE EFFECT OF THERMAL AGING ON CARBON-FIBER-REINFORCED POLYETHERETHERKETONE (PEEK) .2. MORPHOLOGICAL-CHANGES

The morphological properties of carbon fibre-reinforced PEEK (APC-2) laminates subjected to long-term thermal ageing and cycling treatments have been studied using differential scanning calorimetry and wide-angle X-ray diffraction techniques. This work sought provided a structural explanation for measured changes in mechanical properties. Annealing at 120-degrees had no effect but significant changes in crystal content and crystal perfection occurred at 250-degrees and 310-degrees-C. At 250-degrees-C, for short ageing periods, both crystal growth and perfection processes were observed. For longer ageing periods, there was a multiple increase in capital perfection. Initial ageing at 310-degrees-C caused rapid crystal growth, but further ageing resulted in a reduction in measured crystal contents due to thermal degradation.