Studies On The Synthesis And Properties Of Linear Saturated Polyesters And Copolyesters

A Series of linear saturated fatty-aromatic homo-polyesters (Polyehtylene terephthalate, PET; Polytrimethylene terephthalate, PTT; Polybutylene terephthalate, PBT; Polyethylene isophthalate, PEI; Polyethylene-2,6-naphthalate, PEN) and co-polyesters (PEIT, PENT, PEET) have been synthesized under the same conditions. The kinetics have been studied and compared, and the activation energies have been obtained for the esterification, ester-exchange reaction, and polycondensation. It has been shown that with the increase of secondary methyl(-CH2-), the rates of the reactions above decrease. The activations energies for esterification of TPA and PDO, IPA and EQ NDA and EQ and the activation energies for the polycondensation of PTT, PEI, PEN have not been reported on literature up to now.The study results of transition temperatures have shown that: the homo-polymer of PEI is not crystalline; with IPA leading into the macromolecules, the glassy transition and melting temperatures of PEIT decrease, the cold crystallization temperature of PEIT increases; with NDA leading into the macromolecules, the glassy transition and cold crystallization temperatures of PENT increase, the melting temperature of PENT increases; with PEG leading into the macromolecules, the glassy transition temperature, the cold crystallization temperature and the melting temperature of PEET all decrease.The isothermal and non-isothermal crystallization of homo-polyesters by themethod of DSC have shown that: the crystallization of PTT and PBT is fastest, that of PEN is slowest. The crystallization rates of co-polyesters with depolarized method have shown that with the quantities increase, IPA makes PEIT crystallization slowly, NDA makes PENT crystallization slowly, PEG make PEET crystallization quickly.Rheology results have shown that the rheological activation energies(En) of PET, PTT, PBT are quite similar, the En of PEI is bigger, and î—‰ of PEN is the biggest. For copolyesters, with the increases of IPA and NDA contents, the rheological activation energies(E,) of PEIT and PENT all increase. The rheological activation energies(Ea) of PEET mainly depends on the molecular weights of PEG...