生物可降解聚丁二酸/甲基丁二酸丁二酯系列共聚物的合成和表征

Synthesis and Characterization of Biodegradable Poly(butylene succinate-co-butylene methyl succinate)

合成了一系列聚丁二酸／甲基丁二酸丁二醇共聚酯（PBSM），利用DSC，^1HNMR和X射线衍射等方法对共聚物组成、热学性能、结晶性能、等温结晶行为进行了研究．结果表明，引入甲基丁二酸共聚单元较为显著地改变了聚丁二酸丁二酯（PBS）的热学性能，利用Hoffman-Weeks方程得到的共聚物平衡熔点随共聚物的组分含量增加而降低，玻璃化转变温度亦有所降低，熔点则符合无规共聚物的Flory方程．此外，利用Avrami方程分别研究了均聚物PBS及共聚物PBSM-20的等温结晶行为，结果表明，在所研究的温度范围内，聚酯结晶速率随温度升高而降低，PBS和PBSM-20的Avrami指数分别介于2．8～3．0和2．7～3．0之间，结晶方式为三维生长异相成核，而X射线衍射测试结果表明晶体结构几乎不变．

A series of polyesters PBSM, poly （ butylene succinate-co-butylene methyl succinate）, were obtained by direct melting polycondensation of succinate and methyl succinic acid with 1,4-butanediol. The compositions and physical properties of the resulted homopolyester and copolyesters were investigated by i H NMR, differential scanning calorimetry（DSC） and X-my diffraction. The results suggest that the introduction of comonomer containing a side-chain methyl group led to a change in thermal properties and crystallization behavior. The DSC analysis indicates that with the increase of comonomer content, the Tg, Tm, Tm^0 and crystallinity were decreasing gradually, and the depression of Tm followed Flory＇ prediction for random copolymer. Furthermore, an Avrami method was used to analyze the kinetics of isothermal crystallization of PBS and PBSM-20. The Avrami exponents, estimated by Avrami plots, ranging from 2.8 to 3. 0 for PBS and 2. 7 to 3.0 for PBSM-20 indicate that the mechanism of crystallization for both homopolyester and copolyester was a tridimensional growth with heterogeneous nucleation. Meanwhile, X-ray analysis shows that there was almost no effect of the methyl succinate unit on the crystal structure.