The crystalline structures and transitions of poly(phthalazinone ether sulfone) (PPES)/monomer casting (MC) nylon 6 composites were studied by wide-angle X-ray diffraction (WXRD) and Fourier-transform infrared (FTIR) spectroscopy. WXRD analyses demonstrated that the γ-form crystals of quenched samples could transform into a-form crystals by raising the annealing temperature. And increasing the PPES content promoted the γ→α form transition, which was conducive to crystallizing in the stable α-form crystal. FTIR analyses indicated that the α-form crystals of the pristine samples could transform to γ-form crystals through treating with aqueous I₂/KI. The inclusion of PPES to MC nylon 6 hindered the α→γ form transition, which was conducive to crystallizing in the stable α-form crystal. Two consistent observations have come from these studies: PPES favored the α-form crystal in PPES/MC nylon 6 composites. The crystalline transition mechanism was the strong interactions between PPES and MC nylon 6 anchored the antiparallel chains hydrogen bonding of the a-form crystal.

Keywords: poly(phthalazinone ether sulfone), monomer casting nylon 6, composite, crystalline structure, crystalline transition.