MOLECULAR CHAIN STRUCTURE AND CRYSTALLINE STRUCTURE OF PB-ET COPOLYESTER

The molecular chain structure and crystalline structure of PB-ET copolyester made by con-densation polymerization are studied by means of;C nuclear magnetic resonance spectroscopy(;C NMR),dynamic mechanical analysis （DMA）,wide angle X-ray scattering （WAXS）,depolarized light intensity （DLI） and stress-strain measurement（S-S）.It is shown that PB-ETcopolyester is a random copolymer.Because of different ratios of EG（ethylene glycol）to BD（butane diol）in the copolyester,its crystalline forms and mechanical properties vary remarkably.With the increasing amount of BD,its crystallization kinetic parameters n,k and t;increaserapidly.When EG/BD equals 25/75 （mole ratio）,the copolyester has αβ transition as PBTdoes.