POLYAMIDES AND POLYESTER FROM TETRAFLUOROTEREPHTHALIC ACID

Abstract

Polyamides and polyester were prepared from tetrafluoroterephthalic acid (T_F4) and diamines (hexamethylenediamine, piperazine, p-phenylenediamine and 4, 4′-diaminodiphenyl ether) or bisphenol A by the interfacial or low temperature solution polycondensation. The effect of fluorine substitution on synthesis and properties of these polymers were investigated by comparing with those of the homologous polymers prepared from terephthalic acid (T) or tetrachloroterephthalic acid (T_Cl4).
η_sp/C decreased generally in the order for the polymers from T_??_T_F4>T_Cl4. IR of the polymer from T_F4 showed an absorption of C-F bond at 1230cm^-1. T_m, measured by DTA decreased in the order T>T_Cl4>T_F4, while the crystallinity estimated by DTA peak area decreased in the order T>T_F4>T_Cl4. Thermal stability of the polymers estimated by TG was found to decrease in the order T>T_Cl4>T_F4. Flame-retardancy estimated by flash-point measurement increased by the fluorine substitution as well as the chlorine one. Solubility of the polymers increased in the following order T<T_Cl4<T_F4. The difference in behaviour between the polymers from T_F4 and that from T_Cl4 can be explained mainly by the smaller van der Waals radius and lower intermolecular cohesion energy of the fluorine atom.