注塑发泡木塑复合材料微孔结构及增韧改性

Microcellular Structure and Toughening Modification of Injection Molded Foamed Wood/Plastics Composite

通过调整注塑工艺参数(注射温度、保压压力)制备具有不同微孔结构的PP木/纤维复合材料,测试试样的孔隙率、微孔孔径、微孔密度、冲击韧性。通过扫描电镜(SEM)观察试样的断面形貌,研究注塑工艺参数与发泡PP木/纤维复合材料微孔结构和冲击性能的关系。结果表明:注射温度为180℃、保压压力为10 MPa时,所得微孔平均孔径为53μm,微孔密度为2.8×106个/cm3,微孔为"蜂窝"状形貌。与未发泡的相比,密度降低22%,冲击韧性提高60%。其原因是微孔改变裂纹扩展方向,形成"台阶"、"分叉",从而增加其扩展路径,同时微孔使周围基体变形时易产生强迫高弹形变。

Foamed polypropylene/wood-fiber composite （ FWPC ） were prepared by injection molding process. The influence of injection molding processing parameters（ including injection temperature and dwell pressure） on the microcellular structure and the impact strength was investigated. A comparative study of microcellular structure, the porosity and impact ductility of FWPC was conducted. Microcellular structure was observed using scanning electron micrographs （ SEMs）. The results indicated that when the melting temperature was 180 ℃ and pressure was 10 MPa, the composite showed uniformly distributed microcellular structure. The reasons were propagation direction of crack changed by skip mechanism or bifurcation mechanism due to microcellular, and the surrounding matrix of microeellular was easy to produce forced high-elastic deformation.