流动场诱导成核剂TMC-300取向分布对聚乳酸性能的影响

Influence of Flow Field Induced TMC-300 Orientation on Performances of Poly (lactic acid)

聚乳酸(PLA)分子链呈半刚性,结晶速率缓慢导致PLA制品几乎都为非晶态或低结晶度态。制品的耐久性与韧性较差,极大地限制了其在工业领域的应用。文中首先添加高效有机成核剂TMC-300用以改善其结晶性能,研究了TMC-300含量对其成核效率的影响;随后利用多级拉伸复合应力场诱导TMC-300取向分布研究其对PLA结晶及力学性能的影响。结果表明,TMC-300在多级拉伸复合应力场的诱导下沿流动方向取向分布,继而诱导PLA片晶垂直其轴向方向生长,实现PLA片晶沿流动方向的高度取向。在PLA/1%TMC-300体系中,PLA的结晶度达到38%,拉伸强度及断裂伸长率分别达到了92 MPa与32%。

Poly(lactic acid)(PLA) exhibits slow crystallization rate due to its semi-rigid molecular chains, which brings about the fact that almost all PLA products are amorphous or with low crystallinity. The durability and toughness of the products are very poor, which greatly limits its application in the industrial field. In this paper, TMC-300 was added to improve the crystallization performance of PLA products. The effect of nucleating agent contents on the nucleating efficiency was studied. Subsequently, the TMC-300 orientation was induced by a special extensional flow field offered by the self-developed multi-stretch extrusion technology, and the influence of this induction on the crystallization and mechanical properties of PLA was studied. The results show that TMC-300 is oriented along the flow direction then induces the PLA lamellas to grow vertically along its axial direction, which at last realizes a high degree of the orientation of the PLA lamellas along the flow direction. In the PLA/1% TMC-300 system, the crystallinity of PLA reaches 38%, the yield strength and elongation at break reach 92 MPa and 32%, respectively.