THERMAL TRANSITIONS IN POLY(ALKYL-4,4'-DIPHENOXY TEREPHTHALATE)S

The thermal transitions of poly(alkyl-4,4'-diphenoxy terephthalate)s, in which the flexible spacer contains 5,6 and 7 methylene groups, have been studied by thermogravimetry, differential scanning calorimetry, X ray diffraction, thermoptical microscopy and small angle light scatt ering. The series shows a marked influence of the even and odd number of methylene groups on the crystal-liquid crystal transition temperatu res and on the isotropization transition temperature. Nematic mesophas es have been observed for the odd terms, and a transition from a smect ic to a nematic mesophase has been observed for the even term.