WHISKERS .3. WHISKERS OF POLY(ESTER-IMIDE)S DERIVED FROM 4-HYDROXPHTHALIC ACID

N-(4-Carboxyphenyl)-4-acetoxyphthalimide was prepared from 4-hydroxyphthalic acid and polycondensed under various reaction conditions. Only a highly purified monomer yields whisker-like crystals. Cocondensations with 4-acetoxybenzoic acid were conducted over a broad range of molar composition (feed ratio), and whiskers were obtained in all cases. These whiskers were characterized by elemental analyses, WAXS patterns, scanning electron micrographs, and DSC measurements. Regardless of composition they possess the same type of orthorhombic crystal lattice and a degree of crystallinity above 85 %. All attempts to obtain whiskers from the isomeric monomer, i.e., N-(4-acetoxyphenyl)trimellitic acid, failed, even when copolyesters with acetoxybenzoic acid were prepared.