Synthesis and characterization of poly(p-phenylene terephthalate) crystals obtained by crystallization during polymerization
Poly(p-phenylene terephthalate) (PPTE) crystals were prepared by hightemperature solution polymerization via three different types of reaction as follows: bimolecular condensation of (1) 1,4-diacetoxybenzene and terephthalic acid and (2) hydroquinone and diphenyl terephthalate and self-condensation of (3) mono(4'-acetoxyphenyl) terephthalate. In spite of the reaction types, needle-like crystals are not obtained as found with poly(oxy-l,4-benzenediylcarbonyl) (POB) whiskers, under polymerization conditions identical with those used to produce POB whiskers. PPTE and POB have similar molecular structure that is, they comprise 1,4-phenylene groups and ester linkages. whereas the morphologies of the crystals obtained are quite different. From the structural study, PPTE crystals are single crystals, and polymer chains align perpendicular to the plane of the sheaf-like or plate-like crystal.