聚乳酸/纳米SiO2复合纤维的制备及力学性能

首先用硅烷偶联剂(GPS)对纳米SiO2进行接枝改性,利用粒径分析仪、FTIR和沉降实验对改性前后纳米SiO2的粒径大小、结构和溶剂稳定性的变化进行了表征;然后将改性前后的纳米SiO2分别与聚乳酸(PLA)在双螺杆挤出机中熔融混合,利用牵伸卷绕装置制备了PLA/SiO2和PLA/M-SiO2(改性后SiO2)复合纤维。利用视频显微镜和单纱强力仪研究了不同纳米SiO2含量对PLA/SiO2和PLA/M-SiO2复合纤维结构形貌和力学性能的影响,以及不同牵伸倍数对PLA/M-SiO2复合纤维结构形貌和力学性能的影响。结果表明M-SiO2粒径明显减小,且硅烷偶联剂结构中的有机官能团与SiO2表面硅羟基发生反应,减少了其表面Si-OH的量,使得M-SiO2表现出良好的溶剂稳定性和分散性;PLA/M-SiO2复合纤维的力学性能较PLA/SiO2复合纤维得到了明显的改善;当改性纳米SiO2含量为1%时复合纤维强度最好;当牵伸倍数为3时复合纤维强度最好。

Preparation and Mechanical Property of PLA/SiO2 Composite Fibers

The modified nano-SiO₂ (M-SiO₂) was prepared using silane coupling agent to graft and modify nano-SiO₂. The particle size, structure and solvent stability of nano-SiO₂ before and after modification were characterized by particle size analyzer, FTIR and settlement experiment, respectively. Then the PLA/SiO₂ and PLA/M-SiO₂ compo-site fibers were prepared using twin-screw extruder with molten mixing and followed by a draft collecting process. The effects of different SiO₂ amounts on structural morphologies and mechanical properties of PLA/SiO₂ and PLA/M-SiO₂ composite fibers, and different drafting ratios on structural morphologies and mechanical properties of PLA/M-SiO₂ composite fibers were studied by optical microscopy and signal-yarn strength tester. The results indicate that the organic modification decrease the particle size of nano SiO₂. The M-SiO₂ possesses excellent solvent stability and dispersion, attributed to the chemical reaction between organic functional groups of silane coupling agent and hydroxyl groups of nano silica surface. Compared to the PLA/SiO₂ composite fibers, the mechanical properties of PLA/M-SiO₂ composite fibers have notable improvements. The PLA/M-SiO₂ composite fibers reach the maximum strength of the fiber, when the M-SiO₂ amount and drafting ratio is 1% and 3 times, respectively.