ANALYSIS OF POORLY CRYSTALLIZED POLYMERS USING RESOLUTION ENHANCED X-RAY-DIFFRACTION SCANS

The use of resolution enhanced X-ray diffraction scans for studying small differences in the structures in poorly crystallized semicrystalline polymers is illustrated with examples from three polymers with different crystallization behaviour, namely nylon 6,6, nylon 6 and poly(chlorotrifluoro ethylene). The effects of small coherence length were deconvolved using maximum entropy methods to obtain clearly resolved peaks. In polymers such as nylon 6,6, the crystalline structure at low levels of crystallinity can be regarded as highly disordered ('paracrystalline') forms of the structures present in highly crystalline samples. In polymers such as nylon 6, it is necessary to identify the presence of less stable crystalline phases. Finally, in some instances, such as in rapidly quenched films of poly(chlorotrifluoro ethylene), transient crystalline phases could be present during initial phases of crystal growth. Coexistence of the crystalline phases, transient crystalline phases and the amorphous phase are discussed.