X-ray diffraction analysis technique for determining the polymer crystallinity in a polyphenylene sulfide composite

The degree of crystallinity in polymers is commonly known to significantly affect their mechanical properties. To that extent, it also affects the mechanical properties--such as compression, buckling, and creep--of thermoplastic composites that are matrix dominant. For this reason, it is important that the degree of crystallinity in a thermoplastic composite be precisely determined, which is the focus of this paper. In particular, the crystallinity for a thermoplastic poly(phenyl ene sulfide) composite reinforced with glass fibers is determined using an X-ray diffraction technique (XRD). While conventional methods have been adopted for homogeneous phases, a modified method has been adopted to account for the heterogeneous nature of the composite. The results have also been compared with results obtained using DSC and DMA techniques, indicating that the XRD method yielded lower values, which are considered to be more accurate. This was attributed to the absence of a recrystallization effect in the XRD method, which was unavoidable in the other two methods.