PLA/木质素基复合材料的非等温结晶动力学

Non-Isothermal Crystallization Kinetics of PLA/Lignin Based Composite

聚乳酸(PLA)存在结晶速度慢、结晶度较低等问题,使其热学性能及力学性能均较差。环氧大豆油(ESO)可以改善PLA的结晶性能,但是ESO与PLA的相容性较差,使其对PLA结晶行为的改善程度有限。采用木质素(LM)改善PLA和ESO的相容性,制备PLA/ESO/LM复合材料,从而调控其结晶行为。为了深入研究ESO/LM对PLA结晶行为的调控机制,采用差示扫描量热仪(DSC)分析PLA/ESO/LM复合材料的结晶行为,并利用Avrami和莫志深等理论模型分别对PLA及PLA/ESO/LM复合材料的非等温结晶动力学行为进行详细的分析。研究结果表明,ESO/LM具有较好的成核作用;在不同的降温速率下,PLA/ESO/LM复合材料的非等温结晶行为更符合莫志深方程,这表明,ESO/LM在PLA结晶过程中作为异相成核剂,可以使PLA的结晶能垒由46.25 kJ/mol降低至5.05 kJ/mol,从而促进结晶形成。

Polylactide(PLA)suffers slowed crystallization rate and relatively low crystallinity,limiting the further practical application.The crystallization behavior had been demonstrated to be improved by bio-based plasticizer such as epoxy soybean oil(ESO).However,the poor compatibility between PLA and ESO hinders the nucleation effected of ESO.Herein,lignin(LM)was incorporated to enhance the compatibility of PLA and ESO,and the crystallization behavior of asprepared PLA/ESO/LM composite was investigated by using differential scanning calorimeter(DSC).Further,the nonisothermal crystallization kinetic behavior of PLA/ESO/LM composite was analyzed in detail by using Avrami and Mo Zhishen theoretical models.The results showed that,ESO/LM played a key role as a nucleating agent;in heterogeneous nucleation manner;the non-isothermal crystallization of the PLA/ESO/LM composite was fitted better by Mo Zhishen’s equation under different cooling rates,further demonstrating that ESO/LM as a heterogeneous nucleating agent played a vital role in effectively reducing the energy barrier decreased from 46.25 kJ/mol to 5.05 kJ/mol required for PLA crystallization and was beneficial for the formation of the PLA crystallization.