不同pH条件下PBS-PPS的降解性能研究

Degradation Property of Block Polyester PBS- PPS under Different pH Conditions

从质量损失率、表面结构形态变化和结晶形态变化等方面,研究了PBS-PPS嵌段聚酯在不同pH条件下的水解情况。结果表明,随着PBS-PPS嵌段聚酯中PPS链段的增加,材料的降解率提高,不同pH条件下材料降解率由高到低排序为:碱性环境(PBS-PPS嵌段聚酯(PBS与PPS的质量比为10:3)在10周内降解率为46.15%)>酸性环境(33.45%)>中性环境(11.46%);聚酯膜的降解从薄膜表面开始,整个过程是一个由外及内逐步深入的过程,并且优先降解无定形区;PPS的引入阻碍了PBS的结晶,随着PPS链段的增加,材料的结晶半径减小。初步探讨了PBS-PPS嵌段聚酯在不同pH环境下的水解机理,实验结论与机理相符。在碱性环境下,PBS-PPS嵌段聚酯能够完全水解,在酸性与中性环境中,酯键水解的同时也伴随着其可逆反应的进行。

Hydrolysis behavior of block polyester PBS- PPS under different pH conditions was studied. The degradability, surface morphology and crystal morphology of the copolymer before and after degradation were also discussed, which demonstrated that with the increasing amount of PPS segments in PBS - PPS block polyester, the material degradation rate increased. The degradation rate under different pH conditions was as follows： alkali environment （46.15%） 〉 acid environment （33.45%） 〉 neutral environment （11.46%）. The degradation process of polyester film started from the membrane surface and was prior to degrade amorphous region. With the increasing of PPS segments, the crystallization radius of the material was reduced, which mainly due to the introduction of PPS hindered the crystallization of PBS. The experiment result of hydrolysis under different pH conditions was consistent with hydrolysis mechanism for block polyester PBS- PPS. Under the alkali environment, hydrolysis was complete. However, under the acid environment and neutral environment, the hydrolysis of ester bond was accompanied with its reversible reactions.