PP-g-(MAH/St)和PP-g-MAH对聚丙烯/木粉复合材料性能的影响

在转矩流变仪中用熔融接枝法制备马来酸酐(MAH)和苯乙烯(St)接枝聚丙烯（PP）-PP-g-(MAH/St)和PP-g-MAH，将其作为聚丙烯/木粉复合材料的相容剂。 FTIR证实MAH和St单体与PP发生接枝反应。 用SEM和DSC等手段考察两种相容剂对PP/木粉复合材料微观形貌和结晶性能的影响，探索了各种PP/木粉复合材料加工和力学性能不同的内在原因。 SEM显示，PP-g-(MAH/St)改性木粉比PP-g-MAH改性木粉在PP基体中分散性更佳，木粉与PP的界面更加模糊，相容性进一步改善。 DSC结果表明，PP-g-(MAH/St)改性体系可增强木粉对PP的异相成核作用，提高结晶温度和结晶度。 复合材料的加工和力学性能测试结果表明，PP-g-(MAH/St)改性效果明显优于PP-g-MAH。 复合材料的熔体质量流动速率随相容剂用量的增加而逐步下降，PP-g-(MAH/St)改性体系拉伸强度和弯曲强度却逐步上升，并在相容剂用量为4.8 g/100 g PP时达到极值。 此时其拉伸强度达40.62 MPa，分别是未改性体系和PP-g-MAH改性体系的1.29和1.17倍；其弯曲强度达45.72 MPa，分别是未改性体系和PP-g-MAH改性体系的1.23和1.59倍；而无缺口冲击强度却在相容剂用量为3.6 g/100 g PP时达到极值13.35 kJ/m2，分别是未改性体系和PP-g-MAH改性体系的1.62倍和1.42倍。

Effects of PP-g-(MAH/St) and PP-g-MAH on the Properties of Polypropylene/Wood Flour Composites

PPg(MAH/St) and PPgMAH were prepared by melt grafting polypropylene(PP) resin with maleic anhydride(MAH) and styrene(St) in a torque rheometer, and were used as compatiblizers in polypropylene/wood flour composites. The structures of PPg(MAH/St) and PPgMAH were confirmed by FTIR analysis. The effect of these two compatiblizers on the microstructure and crystal properties of PP/wood flour composites was examined by SEM and DSC to interpret and explain the difference of processing and mechanical properties of PP/wood flour composites. SEM analysis indicates that wood flour modified by PPg(MAH/St) has better dispersion in the PP matrix with a blurrier interface and better compatibility than that modified by PPgMAH. DSC results show that the heterogeneous nucleation of wood flour to PP in PPg(MAH/St) modified system is stronger and their crystallization temperature and crystallinity increase. The processing and mechanical properties of PP/wood flour composites reveal that PPg(MAH/St) has better performance than PPgMAH. The meltmess flow rate of the two kinds of composites shows a steady downward trend with the increase of compatiblizer contents, while the tensile and flexural strength of PPg(MAH/St) modified system show a steady upward trend, and reach a maximum at 4.8 g PPg(MAH/St)/100 g PP. The tensile strength reachs to 40.62 MPa which is 1.29 and 1.17 times of the unmodified system and PPgMAH system, respectively, and at the meantime the flexural strength rises to 45.72 MPa which is 1.23 and 1.59 times as high as those of the unmodified system and PPgMAH system. At 3.6 g PPg(MAH/St)/100 g PP, the unnotched impact strength of PPg(MAH/St) system is 13.35 kJ/m2 which is 1.62 and 1.42 times as high as that of unmodified and PPgMAH system, respectively.