POLYMORPHIC CRYSTAL FORMS AND MORPHOLOGY OF SYNDIOTACTIC POLYSTYRENE IN MISCIBLE STATES

X-ray diffraction and optical microscopy characterization were perform ed to evaluate the phenomenon of alteration of polymorphism of syndiot actic polystyrene (s-PS) in the presence of other blending miscible po lymers: poly(2,6-dimethyl-p-phenylene oxide) (PPO) or atactic polystyr ene (a-PS). Both alpha and beta crystal forms were observed in the nea t s-PS sample, but only p-form crystal was found in miscible blends of s-PS with a-PS or PPO. The order and neighboring chain segments of ne at s-PS are different from those of s-PS/PPO or s-PS/a-PS blends; thus , it is plausible that the greater randomness in the melt state of s-P S/a-PS or s-PS/PPO blends might be unfavorable for formation of alpha- form crystals from melts. The final spherulitic morphology the s-PS/a- PS or s-PS/PPO blends suggests that the amorphous-state miscibility of does not change much the spherulitic structure of s-PS. The radial gr owth rate is, in general, depressed with the presence of blending misc ible polymers in s-PS of equal T-g or PPO of higher T-g. (C) 1998 John Wiley & Sons, Inc.