左旋聚乳酸/聚己内酯/氧化锌复合材料的制备及性能

Preparation and Properties of Poly(L-lactic acid)/Polycaprolactone/ZnO Nanocomposites

基于左旋聚乳酸(PLLA)固有低韧性的缺点,分别引入可降解且柔韧性好的聚己内酯(PCL)和刚性纳米粒子氧化锌(nano-ZnO)对其改性,通过溶液共混的方法制备了PLLA/PCL/ZnO复合材料。借助DSC、DMA考察了复合材料的热行为和粘弹性,研究发现,PCL和ZnO的引入对PLLA复合材料的玻璃化转变温度没有影响,说明复合材料是不相容体系;随着PCL、ZnO含量的增多,PLLA的熔融峰向低温偏移。拉伸实验结果表明,PLLA/2%PCL/1%ZnO组分的复合材料拉伸韧性最佳,断裂伸长率达到了35%,比纯PLLA的断裂伸长率提升了20倍。然而,相同比例的PCL和ZnO单独对PLLA改性时,断裂伸长率分别为17%和4%,说明两者协同作用的增韧效果更好。拉伸断面的观察结果表明,PCL/ZnO含量增多时PCL分散相尺寸增大、相分离显著,且ZnO粒子趋于聚集,因而导致增韧效率下降。

Based on the inherent low toughness of PLLA,the biodegradable and flexible PCL and rigid ZnO nanoparticles were introduced to modify it.PLLA/PCL/ZnO nanocomposites were prepared by solution blending.The thermal behavior and viscoelasticity of the composites were investigated by DSC and DMA separately.It is found that the introduction of PCL and ZnO has no effect on the glass transition temperature of PLLA,indicating that the composites are incompatible.With the increase of PCL and ZnO content,the melting peak of PLLA shifts toward low temperatures.The largest break elongation reaches 35%for PLLA/2%PCL/1%ZnO composite,which is 20 times higher than that of pure PLLA.However,the elongation at break is 17%and 4%respectively when PLLA is toughened by PCL and ZnO alone with the same proportion.It indicates that the toughening effect is better for the synergistic effect by the addition of PCL and ZnO both.The SEM observation of the tensile fracture surface shows that the size of PCL dispersed phase increases resulting from phase separation and ZnO particles tend to aggregate with the increasing content of PCL/ZnO,resulting in a decrease in toughening efficiency.