左旋聚乳酸/右旋聚乳酸嵌段共聚物的共混物及其纤维的结构与性能

以右旋聚乳酸-聚乙二醇-右旋聚乳酸(PDLA-PEG-PDLA)三嵌段共聚物作为改性剂,通过熔融共混法及熔融纺丝-后牵伸两步法分别制备了左旋聚乳酸(PLLA)/PDLA-PEG-PDLA共混物及其共混纤维。采用差示扫描量热分析、热重分析、毛细管流变仪、扫描电镜、广角X射线衍射及力学性能测试等方法对共混物及其共混纤维的结晶行为、热性能、取向及力学性能等进行了研究。结果表明,熔融温度对PLLA及其共混物的结晶行为有较大的影响。当熔融温度为230℃时,共混物中PDLA-PEG-PDLA含量为10%时,α晶的结晶温度最高,为127℃;另外,共混物具有较好的纺丝性能,相同条件下制备的共混纤维的结晶度和取向度均高于纯PLLA纤维,当嵌段共聚物质量分数为2%时,共混纤维的结晶度及取向度最大,分别为27%和-0.39;嵌段共聚物的加入,对PLLA的热稳定性和力学性能的影响较小。

Preparation and Properties of Poly(L-Lactic Acid)/Poly(D-Lactide)Block Copolymer Blends and Its Fibers

Poly (L-Lactide) (PLLA)/poly (D-Lactide)-poly (ethylene glycol)-poly (D-Lactide) (PDLA-PEG-PDLA) triblock copolymer blends and fibers were prepared by melting blend and two-step melt spinning.The crystallization behavior,thermal properties,orientation and mechanical properties were investigated by DSC,TG,capillary rheological,SEM,WAXS and mechanical tests.The results show that melting temperature has a significant impact on the crystallization behavior of PLLA/PDLA-PEG-PDLA blends.Upon cooling from 230 ℃,the highest crystallization temperature for a form at about 127 ℃ is observed in the PLLA/PDLA-PEG-PDLA (90/10) blends.PLLA/PDLA-PEG-PDLA blends own good spinnability.The crystallinity and orientation of PLLA/PDLA-PEG-PDLA fibers are higher than that of the PLLA fiber.As the content of PDLA-PEG-PDLA is 2 ％,the crystallinity and orientation of the fibers are about 27 ％ and-0.39,respectively.The heat stability and mechanical properties of PLLA fibers are less affected by the addition of PDLA-PEG-PDLA.