GLASS-TRANSITION, CRYSTALLIZATION, AND MORPHOLOGY RELATIONSHIPS IN MISCIBLE POLY(ARYL ETHER KETONES) AND POLY(ETHER IMIDE) BLENDS

The relationships among glass transition, crystallization, melting, and crystal morphology of poly(aryl ether ketone) (PAEK) /poly(ether imide) (PEI) blends was studied by thermal, optical and small-angle x-ray scattering (SAXS) methods. Two types of PAEK were chosen for this work: poly (aryl ether ether ketone), PEEK, and poly (aryl ether ketone ketone), PEKK, which have distinctly different crystallization rates. Both PAEKs show complete miscibility with PEI in the amorphous phase. As PAEK crystallizes, the noncrystallizable PEI component is rejected from the crystalline region, resulting in a broad amorphous population, which was indicated by the broadening and the increase of T(g) over that of the purely amorphous mixture. The presence of the PEI component significantly decreases the bulk crystallization and crystal growth rate of PAEK, but the equilibrium melting temperature and crystal surface free energies are not affected. The morphology of the PEI segregation was investigated by SAXS measurements. The results indicated that the inter (lamellar-bundle) PEI trapping morphology was dominant in the PEEK/PEI blends under rapid crystallization conditions, whereas the interspherulitic morphology was dominant in the slow crystallizing PEKK/PEI blends. These morphologies were qualitatively explained by the expression delta = D / G, where G was the crystal growth rate and D was the mutual diffusion coefficient.