【摘要】 利用差示扫描量热法(DSC)研究了三臂L-乳酸-b-D-乳酸(PLLA-b-PDLA)嵌段共聚物的非等温结晶及熔融行为。引入单位时间结晶程度来表征非等温结晶速率,运用Avrami和Ozawa等方法分析了三臂PLLA-bPDLA嵌段共聚物的非等温结晶及熔融行为。结果表明:3种三臂PLLA-b-PDLA嵌段共聚物TLD1/0.5、TLD1/1和TLD1/2.5的立构复合晶体最快结晶速率分别为19.9、7.2和4.5%/min,其Ozawa指数均在2~3之间,说明三臂PLLA-b-PDLA嵌段共聚物非等温结晶形成了球晶。另外,聚乳酸立构复合晶体和聚乳酸均聚物晶体的形成与分子链组成、结构和冷却速率有关。其中当冷却速率高于20℃/min时,TLD1/1和TLD1/0.5仅能生成立构复合晶体。更多还原

【Abstract】 The non-isothermal crystallization behavior of tri-arm poly(L-lactide)-b-poly(D-lactide)(PLLAb-PDLA) was investigated by differential scanning calorimetry(DSC). The per unit time crystallinity was introduced to evaluate the non-isothermal crystallization rate, and the methods of Avrami and Ozawa were used to analyze the non-isothermal crystallization behavior and melting behavior of tri-arm PLLA-b-PDLA. The results show that the fastest crystallization rates of the three kinds of tri-arm PLLA-b-PDLA(TLD1/0.5, TLD1/1 and TLD1/2.5) are 19.9, 7.2 and 4.5%/min, respectively. And the Ozawa exponents are in the range of 2~3, which reveals that the truncated sphere or spherical crystals might be formed during non-isothermal crystallization. Moreover, the formation of stereocomplex crystals and homopolymer crystals is controlled by chain composition, chain structure and cooling rate. TLD1/1 and TLD1/0.5 could only form stereocomplex crystals when the cooling rate is above 20℃/min.更多还原