聚乳酸/聚烯烃弹性体共混体系的发泡行为

Foaming behavior of poly(lactic acid)/polyolefin elastomer blends

为研究聚乳酸(PLA)共混体系的界面相互作用对发泡材料泡孔结构的影响,选择聚烯烃弹性体(POE)和马来酸酐接枝聚烯烃弹性体(POE-g-MAH)分别与PLA共混,制备PLA/POE和PLA/POE-g-MAH共混物,然后利用釜压发泡,制备共混体系发泡材料。首先,利用扫描电子显微镜(SEM)观察了POE和POE-g-MAH在PLA中的分散情况;然后,利用旋转流变仪研究了PLA/POE和PLA/POE-g-MAH共混体系的流变行为;最后,利用SEM研究了PLA/POE和PLA/POE-g-MAH共混体系发泡材料的泡孔结构,通过测试样品发泡前后的密度计算了膨胀倍率,并探讨了界面相互作用对泡孔结构的影响。结果显示,随着弹性体含量增加,POE和POE-g-MAH的相区尺寸都随之增大,后者的相区尺寸较小;POE和POE-g-MAH含量增加,体系的复数黏度和储能模量也都增大,由于后者与PLA的界面相互作用更强,因此其体系复数黏度和储能模量增大得更显著;当弹性体质量分数为10%和20%时,POE的加入可增强体系的气泡异相成核,因此形成的泡孔尺寸较小,而POE-g-MAH的加入有利于泡孔生长,因此形成的泡孔尺寸较大;在90℃发泡后,PLA/POE-g-MAH10和PLA/POE-g-MAH20发泡材料的膨胀倍率比PLA/POE10和PLA/POE20的更大。

To study the effect of interfacial interaction of poly(lactic acid)(PLA)blends on cell structure,polyolefin elastomer(POE)and POE grafted with maleic anhydride(POE-g-MAH)were chosen to mix with PLA to prepare PLA/POE and PLA/POE-g-MAH blends,and then the blend foams were prepared via batch foaming process.First,the dispersion of POE and POE-g-MAH in PLA were observed using scanning electron microscope(SEM).Then,the rheological behavior of PLA/POE and PLA/POE-g-MAH blends were studied with rheometer.Last,the cell structure of PLA/POE and PLA/POE-g-MAH blend foams were studied with SEM,the expansion ratio of the foams was obtained via measuring the density before and after foaming,and the effect of interfacial interaction on cell structure was discussed.The results show that with increase in elastomer content,the phase domains of POE and POE-g-MAH both increase,and the latter has smaller phase domains.With increase in POE and POE-g-MAH content,the complex viscosity and storage modulus of both blends increase.POE-g-MAH has stronger interfacial interaction with PLA,and resultantly,the complex viscosity and storage modulus of the blend increase more significantly.With elastomer content of 10%and 20%,the heterogeneous cell nucleation is enhanced for PLA blends with POE,and hence,the cell size is smaller.The cell growth is facilitated for PLA blends with POE-g-MAH,and hence,the cell size is larger.For foams prepared at 90℃,PLA/POE-g-MAH10 and PLA/POE-g-MAH20 have larger expansion ratio than PLA/POE10 and PLA/POE20.