PP-g-MAH对PLA性能的影响

Effects of PP-g-MAH on Properties of PLA

采用双螺杆挤出机以熔融共混法制备了聚乳酸(PLA)和马来酸酐接枝聚丙烯(PP-g-MAH)共混物,以傅立叶变换红外光谱(FTIR)、热重(TG)分析、动态热机械分析(DMA)和扫描电子显微镜研究了不同PP-g-MAH含量对PLA力学性能和微观结构的影响。DMA测试发现,随着PP-g-MAH含量的增加,PLA/PP-g-MAH共混物的损耗因子向低温区移动,表明PLA与PP-g-MAH分子链具有良好的相容性。FTIR分析证实了这种良好的相容性归因于PLA分子链羟基和酸酐基团之间的酯化反应。TG分析研究表明,PP-g-MAH的加入限制了PLA分子链的运动,提高了共混物的耐热性,一定程度上抑制了PLA的分解。PP-g-MAH在一定程度上提高了PLA/PP-g-MAH共混物的力学性能,添加质量分数15%的PP-g-MAH时,PLA/PP-g-MAH共混物的Iozd缺口冲击强度和弯曲弹性模量都有所提高,分别由纯PLA的2.83 k J/m2,2 668 MPa提高到5.38 k J/m2,2 970 MPa,分别提高了90.1%和11.3%,但拉伸强度却有一定程度的降低。阻隔性能实验表明,随着PP-g-MAH含量的增加,水蒸气和氧气透过系数降低。添加质量分数20%的PP-g-MAH,氧气和水蒸气的透过系数分别为4.5×10-15(cm3·cm)/(cm2·s·Pa)和1.3×10-10 g/(m·s·Pa),与纯PLA相比,分别下降了74.7%和45.1%。

Polylactic acid(PLA)and maleic anhydride grafted polypropylene(PP-g-MAH)blends were prepared by melt blending with twin-screw extruder.The effects of different PP-g-MAH content on the mechanical properties and microstructure of PLA were studied by FTIR,DMA,TG and SEM.DMA measurements show that the loss factors of the PLA/PP-g-MAH blends move to the low temperature region,which indicate that the PLA and PP-g-MAH molecular chains have good compatibility.FTIR confirms that this good compatibility is attributed to the esterification between hydroxyl groups and anhydride groups in PLA molecules.The TG analysis shows that the addition of PP-g-MAH limits the movement of PLA molecular chains,which improves the heat resistance of the blends,and inhibits the decomposition of PLA to some extent.PP-g-MAH improves the mechanical properties of PLA/PP-g-MAH blends to some extent.When the mass fraction of15%PP-g-MAH is added,the Iozd notched impact strength of blend is increased from2.83kJ/m2of pure PLA to5.38kJ/m2,the flexural modulus of elasticity of blend is increased from2668MPa of pure PLA to2970MPa,which increase by90.1%and11.3%,respectively.While the tensile strength is reduced to certain extent.The barrier performance test shows that the water vapor and oxygen permeability decrease with the increase of PPg-MAH content.When the mass fraction of20%PP-g-MAH is added,the transmittance coefficients of water vapor and oxygen are4.5×10-15(cm3·cm)/(cm2·s·Pa)and1.3×10-10g/(m·s·Pa),which are74.4%and45.1%lower than pure PLA respectively.