THE CRYSTALLINITY OF PEEK COMPOSITES

Measurement of the degree of crystallinity of the polymer matrix in a composite is complicated by the presence of the reinforcing additive. This is particularly the case in poly(ether ether ketone) carbon fibre composite, APC-2, which may contain as much as 70% carbon fibre. A Fi rst Law procedure, developed for determining the degree of crystallini ty of poly(ether ether ketone) (PEEK), has been outlined previously. I t involved direct measurement of the enthalpy-changes associated with melting, crystallization and heat capacity changes, and was found to b e an effective method for determining the crystallinity of the PEEK ma trix. The procedure has been applied to carbon fibre and glass fibre P EEK composites.