Abstract: Copolyester (BPET) modified with trimethylolpropane (TMP) was prepared through direct esterification and melt polycondensation method. Their structure and properties, crystallization and rheological behaviors were characterized. With TMP content increasing, the half crystallization time of BPET became longer and the melt crystallization peak temperature decreased. The non-Newtonian index of BPET melt became smaller and the dependence of the apparent viscosity on shear rate increased. The viscous flow activation energy of BPET at the experimental shear rates was lower than that of polyethylene terephthalate, so it would not be suitable to improve BPET’s flowability by rising temperature.

Key words: trimethylolpropane, modified　copolyester, crystallization, rheological behavior