PBT/POE-g-MAH/PP共混体系的相态结构与性能

MORPHOLOGY AND PROPERTIES OF PBT/POE-g-MAH/PP TERNARY BLENDS

采用马来酸酐接枝乙烯-辛烯共聚物弹性体(POE-g-MAH)与聚丙烯(PP)在双螺杆挤出机上进行熔融共混,制备了3种新型增韧改性剂.研究了增韧改性剂的种类及其用量对共混物的力学性能、相形态结构、熔融与结晶行为的影响.力学性能测试表明,POE-g-MAH与适量PP并用具有显著的协同增韧作用,当POE-g-MAH与PP的配比为70/30时,所得增韧改性剂(POEg2)具有最佳的增韧效果.当POEg2含量达到15%时,共混物的缺口冲击强度(Is)从纯PBT的7.5 kJ/m2提高到51.2 kJ/m2,与15%的纯POE-g-MAH弹性体增韧PBT具有相近的缺口冲击强度值.同时,共混物的拉伸强度(σb)损失最小.采用AFM和SEM观察发现,新型增韧改性剂作为分散相具有软壳-硬核结构.DSC测试表明,随增韧改性剂中PP含量增加到一定值时,壳-核结构中软壳层出现不完整现象,导致界面作用力减小,共混物的Is和σb都出现明显下降.

Three types of novel impact modifiers were prepared by melt blending maleic anhydride-grafted ethyleneoctene copolymer （POE-g-MAH） with polypropylene （PP） through a twin screw extruder. The effect of different impact modifier and its content on mechanical properties, dispersion morphology and melting and crystallization behavior of the blends was investigated. The mechanical property testing indicates that POE-g-MAH and PP have significantly synergistic toughening effect on PBT. The impact modifier （POEg2） with POE-g-MAH/PP ratio of 70/ 30 has the best toughening effect. When POEg2 content is up to 15 %, the notched impact strength （ Is ） increases from 7.5 kJ/m^2 for pure PBT to 51.2 kJ/m^2 ,which is approximately equal to that for the blend toughened by 15% pure POE-g-MAH,and the loss of tensile strength （ab） of the blend is the least. The impact modifier particles dispersed in matrix have a soft shell-rigid core morphology evidenced by using AFM and SEM. DSC results reveal that the soft shell in shell-core structural particles becomes incomplete, when the PP content in the impact modifier is high （50%）. It may which result in a decline in interaction between the blend components, and consequently, Is and σb of the blend both begin to decrease obviously.