Study on Structure and Crystallinity of A New Biodegradable Aliphatic-Aromatic Copolyester

A series of biodegradable aliphatic-aromatic copolyesters, poly(butylene terephthalate-co-butylene adipate-co- ethylene terephthalate-co-ethylene adipate) (PBATE), were synthesized from terephthalic acid (PTA), adipic acid (AA), 1,4-butanediol (BG) and ethylene glycol (EG) through direct esterification and polycondensation. The sequence structure and crystallinity of the copolyester were investigated by 1H NMR spectroscopy and the wide-angle X-ray diffractometry (WAXD). The analytical results showed that the PBATE copolyester was a random copolymer and the composition of PBATE copolyester was almost consistent with the feed molar ratios. The crystal structure of PBATE copolyester belonged to the triclinic crystalline system; The variation in melting point of the synthesized PBATE copolyester agreed well with the estimation obtained by the Flory equation and was applicable to the random copolymer.

辛烯基琥珀酸菊粉酯的制备及其结构分析

以取代度（Ds）为指标，利用单因素试验研究了菊粉浓度、反应温度、pH值、OSA添加量等因素对制备辛烯基琥珀酸菊粉酯的影响，通过正交试验确定了适宜制备工艺条件为：菊粉浓度为25％，OSA／AFU摩尔比为0．35，pH8．5～9．0，反应温度30℃，在该工艺条件下所得产品取代度为0．0342。对制备产品的结构采用扫描电镜（SEM）、红外光谱仪（FT-IR）、核磁共振光谱做（^13CNMR和^1HNMR）等进行表征分析，结果表明：菊粉经过辛烯基琥珀酸酐（OSA）修饰后，其颗粒表面受到侵蚀，出现凹槽、破损孔纹。红外光谱图显示菊粉酯化后在1733．72cm^-1、1569．80cm^-1处分别出现酯键中羰基（C=O）振动和OSA上的烯基（C=C）伸缩振动的特征吸收峰。^13CNMR谱图中在化学位移175．6ppm和176．5ppm处出现羰基碳和羧基碳的特征峰；1HNMR谱图中在化学位移1-2ppm、0．8ppm附近出现OSA分子亚甲基和甲基质子峰。这均证实了OSA基团以酯键形式连接到菊粉分子上。