Study On The Synthesis And Properties Of Poly(1,4-Cyclohexyledimethylene Terephthalate) (PCT)

Terephthalic Acid (TPA) and 1,4-cyclohexanedimethanol(CHDM) as the raw materials and titanium as the preferable catalyst were used to prepare the Poly(1,4-cyclohexylenedimethylene terephthalate) (PCT) through the direct esterification and melt-state polycondensation.The effects of esterification condition on the esterification extent and reaction time were studied. The results showed that the best technology was TPA/CHDM=1:1.6, and the content of catalyst was 3.5/104. Based on the esterification kinetics, the reaction activation energy was about 9--15kJ/mol.The results of melt-state polycondensation showed that the product's intrinsic viscosity [η] of PCT is 0.6677dL/g while terminal reaction temperature is 304oC and the stir voltage is 95V. The PCT glassy transition temperature (Tg), crystallization temperature (Tc) and melting point(Tm) were 93.23oC, 135.62oC and 299.65oC, respectively.The intrinsic viscosity decrease of PCT was also studied. It was found that the intrinsic viscosity decrease was obviously with the extension of heat-treatment time. Moreover, the intrinsic viscosity decrease was more severely in the air than in N2 gas flow. The solid-state polycondensation of PCT was firstly studied systematically. The best condition was 26.5h at 250oC, the intrinsic viscosity of the product PCT was 0.9008dL/g. The differential scanning calorimetry (DSC) showed that there were double melting peak for the most products PCT.In the last, the isothermal and non-isothermal crystallization kinetics of PCT was performed by DSC. The classical theory of Avrami model was applied to describe PCT's isothermal crystallization process. It was shown that Avrami equation only represented the initial period of isothermal crystallization. As to non-isothermal crystallization, Ozawa and Jeziomy's equations were not suitable. Mo equation could analyze non-isothermal crystallization of PCT. Using Kissinger equation, the activation energy of non-isothermal crystallization was 16.82kJ/mol.