Aramid/poly(ether sulphone) blend: crystallization accelerated by the presence of amorphous polymer

An aramid, prepared by the polycondensation of bis(4-aminophenyl) ether with isophthaloyl chloride, was found to render a single-phase mixture with poly(ether sulphone) (PES) by solution casting. Crystallization of the blend was studied by wide-angle X-ray diffraction, H v light scattering, differential scanning calorimetry, Fourier-transform infra-red spectroscopy and scanning electron microscopy. The crystallization of aramid was found to be accelerated dramatically by adding PES, e.g. the crystallization rate constant of a 50 50 blend was shown to be one decade higher than that of neat aramid at around 310°C. The accelerated crystallization was ascribed to the elevation of chain mobility of aramid by blending with PES. It may be caused by the decrease of T g via blending of a low- T g component (PES), but this contribution was estimated to be small. The major contribution seems to be due to the partial dissociation of aramid-aramid interactions and the ‘up-hill diffusion’ associated with the liquid-liquid phase separation.