纳米蒙脱土对木粉/聚丙烯复合材料发泡性能的影响

采用高压釜间歇式发泡法，结合超临界CO₂微孔发泡技术制备了发泡木粉-纳米蒙脱土(NMMT)/聚丙烯(PP)复合材料。通过对复合材料的结晶行为、流变性能、泡孔形貌及压缩性能进行分析，主要研究了NMMT对其微孔结构及力学性能的改善作用。结果表明:NMMT的引入使木粉/PP复合材料中PP基体的结晶速率加快，结晶度减小，有利于发泡均相体系的形成和泡孔生长；PP分子链的运动受到NMMT片层的抑制作用，导致木粉/PP复合材料的熔体弹性提高，泡孔合并与塌陷的现象减少，发泡材料的平均泡孔直径从30.4 μm降低至20.3 μm，并且泡孔尺寸的均匀性得到明显改善，压缩强度和模量分别提高了187%和223%。 

Effect of nano-montmorillonite on foaming properties of wood flour/polypropylene composites

The foamed wood flour-nano-montmorillonite (NMMT)/polypropylene (PP) composites were prepared by the batch foaming method using supercritical CO₂ microcellular foaming technology. Effects of NMMT on the microcellular structure and mechanical properties of the composites were explored by investigating crystallization behavior, rheological properties, cell morphology and compression properties. The results show that NMMT accelerates the crystallization rate of the PP matrix in the wood flour/PP composites, and reduces the crystallinity rate. This is beneficial to the formation of foamed homogeneous system and cell growth. The PP molecular chain is inhibited by the NMMT interlayer, resulting in the melt elasticity increasement of the wood flour/PP composites. The phenomena of cell coalescence and collapse are reduced, the average cell diameter of the foamed composites is decreased from 30.4 μm to 20.3 μm, and the uniformity of cell size is obviously improved. The compressive strength and modulus are increased by 187% and 223%, respectively.