非晶聚对苯二甲酸乙二酯的制备与表征

通过单体酯交换法和聚 2 ,6 萘二甲酸乙二酯 (PEN)与低分子量PET酯交换的方法分别合成了一系列NPA/TPA/EG和IPA/TPA/EG共聚酯 .随着NPA或IPA单元含量的增加 ,等温结晶速度迅速降低 ,共聚物的结晶性降低甚至非晶化 .由NMR分析得知单体酯交换法与聚合物酯交换法得到的共聚酯NPA/TPA/EG序列分布相近 ,链结构都接近完全无规 .由DSC结果分析 ,随共聚单体含量的增加 ,熔点和熔融热降低 ,结晶度也随之降低 .当NPA或IPA含量达到 2 0 %时 ,可以得到非晶的共聚酯 (APET) .本文还对共聚物组成与结晶温度的关系进行了表征

PREPARATION AND CHARACTERIZATION OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE)

Copolyesters based upon ethylene glycol(EG),terephthalic acid(TPA) and 2,6-naphthalenedicarboxylic acid(NPA) or isophthalic acid(IPA) of different composition were synthesized by transesterification polycondensation of monomers or polymers.With the involvement of IPA or NPA moieties in the chains,the copolyesters became less crystallizable or amorphous,and the isothermal crystal growth rate decreased rapidly.The H+1-NMR studies of the copolyesters NPA/TPA/EG showed that the samples prepared by different method exhibited a similar random sequence distribution.DSC measurements indicated that the copolyesters NPA/TPA/EG or IPA/TPA/EG are amorphous if the contents of moieties NPA of IPA are higher or equal to 20 mol%.The WAXD of the copolyester sample containing 20 mol% NPA moieties,after an anneal at 140℃ for 2 hours,exhibited some weak diffraction peak,which is attributed to the crystals of PET moiety in the copolyester.Due to the introduction of IPA or NPA moieties,the melting temperatures and the cooling crystallization temperatures of the copolyesters were changed.