不同相对分子质量聚乙二醇增塑聚乳酸共混物的制备与性能

文中探究不同相对分子质量聚乙二醇(PEG)对聚乳酸(PLA)增塑改性的影响。采用转矩流变仪、万能试验机、差示扫描量热分析、动态力学、热重分析、旋转流变仪等测试表征方法对共混材料的增塑效果、力学性能、热行为、流变行为进行分析。实验结果表明,PEG可有效增塑PLA,PEG相对分子质量越低增塑效果越好,可以使PLA的塑化时间从250 s降低到128 s;加入PEG后,共混物的拉伸强度下降,断裂伸长率提高,PEG相对分子质量越低,拉伸强度下降越明显;PEG的加入使PLA的T_g和T_(cc)降低20℃左右,而T_m有所提高,其中低相对分子质量PEG可以更好地促进PLA结晶,但是随着PEG的加入共混体系的热分解温度降低,相对分子质量越低,热分解温度降低越明显;流变实验表明共混体系的复数黏度(η*)、储能模量(G')及损耗模量(G')的变化随PEG相对分子质量的减小下降越明显。

Preparation and Properties of Poly(lactic acid) Plasticized by Poly(ethylene glycol) with Different Molecular Weight

The influence of poly(ethylene glycol) (PEG) with different molecular weight on the plasticization of poly(lactic acid) (PLA) was explored in this study.The plasticizing performance,mechanical properties,thermal behavior,and theological property of the PLA/PEG blending materials were researched by torque rheometer,universal testing machine,differential scanning calorimetry (DSC),dynamic mechanical analyzer (DMA),thermogravimetric analysis (TGA),and rotational rheometer tests.The results show that PLA can be plasticized effectively by adding PEG,in which its plasticization performance increases with decreasing the molecular weight of PEG used,and the plasticization time of the PLA/PEG blends reduces from 250 s of the pure PLA to 128 s.The addition of PEG decreases tensile strength and increases elongation at break of the blends,where the lower molecular weight of PEG is used,the lower tensile strength of the blends will be achieved.The addition of PEG decreases the glass transition temperature(Tg) and cold crystallization temperature(Tcc) around 20 ℃,and increases the melting temperature (Tm) of PLA.Especially,lower molecular weight PEG presents better crystallization capability for PLA.However,the thermal decomposition temperature of the blends decreases with the addition of PEG,and lower molecular weight of PEG presents more decreasing in the thermal decomposition temperature.The theology experiments indicate the complex viscosity (η*),storage modulus (G′) and loss modulus (G") exhibit accelerated decrease with the decrease of molecular weight of PEG.