Fabrication of Time-limited Biodegradable Fibers by Control of Micro- and Macro-scopic Order Structure using Sheath-core Type Bicomponent Melt Spinning

对不同D-丙交酯含量的聚乳酸进行了高速熔融纺丝，并对初生纤维的结构和性能进行了研究。低、中、高D-丙交酯含量的聚乳酸(聚乳酸-L、聚乳酸-M和聚乳酸-H)的最高卷绕速度分别为10、9和8公里/mm。初生纤维的双折射随卷绕速度的增加而增大。随着D-丙交酯含量的增加，在高卷取速度下得到的纤维的双折射降低。聚乳酸-L纤维和聚乳酸-M纤维分别以5和6公里/分钟及更高的速度纺丝，其广角X射线衍射谱显示出明显的晶态反射。晶型为a-晶型。在差示扫描量热图中，由于聚合物结晶度的差异和分子取向对结晶速率的影响，在低卷绕速度区得到的聚乳酸-L纤维观察到冷结晶，而在高卷绕速度区观察到聚乳酸-M…纤维的冷结晶更多的纤维。从差示扫描量热图分析，聚乳酸-L和聚乳酸-M的结晶度随着卷绕速度的增加而增加。聚乳酸-L纤维的结晶度明显高于聚乳酸-M纤维，而聚乳酸-H纤维在达到最高的卷绕速度时是非晶态的。初生纤维的力学性能随卷绕速度的增加而提高。以10 km/min的速度制得的聚乳酸-L纤维的初始杨氏模量和最大强度分别为5.9 GPA和570 Mpa。对不同D-丙交酯含量的聚乳酸进行了高速熔融纺丝，并对初生纤维的结构和性能进行了研究。低、中、高D-丙交酯含量的聚乳酸(聚乳酸-L、聚乳酸-M和聚乳酸-H)的最高卷绕速度分别为10、9和8公里/mm。初生纤维的双折射随卷绕速度的增加而增大。随着D-丙交酯含量的增加，在高卷取速度下得到的纤维的双折射降低。聚乳酸-L纤维和聚乳酸-M纤维分别以5和6公里/分钟及更高的速度纺丝，其广角X射线衍射谱显示出明显的晶态反射。晶型为a-晶型。在差示扫描量热图中，由于聚合物结晶度的差异和分子取向对结晶速率的影响，在低卷绕速度区得到的聚乳酸-L纤维出现冷结晶，而在高卷绕速度区观察到冷结晶。从差示扫描量热图分析，聚乳酸-L和聚乳酸-M的结晶度随着卷绕速度的增加而增加。聚乳酸-L纤维的结晶度明显高于聚乳酸-M纤维，而聚乳酸-H纤维在达到最高的卷绕速度时是非晶态的。初生纤维的力学性能随卷绕速度的增加而提高。以10 km/min的速度制得的聚乳酸-L纤维的初始杨氏模量和最大强度分别为5.9 GPA和570 Mpa。较少

High-speed melt spinning of polylactides with various D-lactide contents was carried out and the structure and properties of the as-spun fibers were investigated. The highest take-up velocities attained for polylactieds with low, middle and high D-lactide contents (PLA-L, PLA-M, and PLA-H) ware 10, 9, and 8 km/mm, respectively. Birefringence of as-spun fibers increased with an increase in the take-up velocity. Fiber obtained at high take-up velocities showed lower birefringence with increasing the D-lactide contents. Distinct crystalline reflections appeared in WAXD patterns of PLA-L and PLA-M fibers spun at 5 and 6 km/min and higher, respectively. The crystal modification was a-form. In DSC thermograms, because of the difference in crystallinity of polymers and the effect of molecular orientation on crystallization rate, cold crystallization was observed for the PLA-L fibers obtained in a low take-up velocity region, whereas in a high take-up velocity region it was observed for PLA-M … More fibers. Crystallinity analyzed from DSC thermograms of PLA-L and PLA-M increased with an increase in the take-up velocity. PLA-L fibers showed significantly higher crystallinity than PLA-M fibers, whereas PLA-H fibers were found to be amorphous up to the highest take-up velocities attained. Mechanical properties of as-spun fibers increased with increasing take-up velocities. The highest initial Young's modulus and tenacity, which were PLA-L fibers obtained at 10 km/min, were about 5.9 Gpa and 570 Mpa, respectively. High-speed melt spinning of polylactides with various D-lactide contents was carried out and the structure and properties of the as-spun fibers were investigated. The highest take-up velocities attained for polylactieds with low, middle and high D-lactide contents (PLA-L, PLA-M, and PLA-H) ware 10, 9, and 8 km/mm, respectively. Birefringence of as-spun fibers increased with an increase in the take-up velocity. Fiber obtained at high take-up velocities showed lower birefringence with increasing the D-lactide contents. Distinct crystalline reflections appeared in WAXD patterns of PLA-L and PLA-M fibers spun at 5 and 6 km/min and higher, respectively. The crystal modification was a-form. In DSC thermograms, because of the difference in crystallinity of polymers and the effect of molecular orientation on crystallization rate, cold crystallization was observed for the PLA-L fibers obtained in a low take-up velocity region, whereas in a high take-up velocity region it was observed for PLA-M fibers. Crystallinity analyzed from DSC thermograms of PLA-L and PLA-M increased with an increase in the take-up velocity. PLA-L fibers showed significantly higher crystallinity than PLA-M fibers, whereas PLA-H fibers were found to be amorphous up to the highest take-up velocities attained. Mechanical properties of as-spun fibers increased with increasing take-up velocities. The highest initial Young's modulus and tenacity, which were PLA-L fibers obtained at 10 km/min, were about 5.9 Gpa and 570 Mpa, respectively. Less