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

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

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。

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 α 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.