挤出工艺及螺杆组合对膨胀阻燃PP性能的影响

利用无卤膨胀阻燃剂对聚丙烯(PP)进行改性,研究了不同挤出工艺参数(温度、螺杆转速、喂料量)及螺杆组合对无卤膨胀阻燃PP材料性能熔体流动速率(MFR)、力学性能、阻燃性能、颜色等]的影响。结果表明,随着喂料量的增加,材料的MFR、断裂伸长率和缺口冲击强度总体呈下降趋势,适宜的喂料量为60 kg/h;随着螺杆转速的增加,材料的MFR逐渐提高,断裂伸长率、缺口冲击强度和极限氧指数呈现先增加后降低的趋势,材料颜色逐渐变黄;随着挤出温度升高,材料的断裂伸长率和缺口冲击强度呈现先升高后降低的趋势;使用弱剪切螺杆组合时阻燃剂分散性能较差,使用集中强剪切螺杆组合时容易导致材料降解,使用分散多段剪切的螺杆组合时,材料的断裂伸长率、缺口冲击强度提升显著,分别比弱剪切螺杆组合生产的材料提高了80%和40.5%。当喂料量为60 kg/h、螺杆转速为500 r/min、挤出温度为180~200℃并采用分散多段剪切的螺杆组合时,无卤膨胀阻燃PP材料的综合性能最优。

Inlfuence of Extrusion Process and Screw Conifguration on Properties of Halogen-Free Intumescent Flame Retardant Polypropylene

Polypropylene (PP) was modified by halogen-free intumescent flame retardant (IFR) and the influences of the ex-trusion process parameters (extrusion temperature,screw speed,feeding quantity) and screw configuration on the properties melt flow rate (MFR),mechanical properties,flame retardance,color) of halogen-free intumescent flame retardant PP materials were researched. The results show that with the increase of feeding quantity,the MFR,elongation at break and notched impact strength decrease in total,the proper feeding quantity is 60 kg/h. As the screw speed increases,the MFR increases,the elongation at break, notched impact strength and limiting oxygen index increase first and then decrease,the color of the material changes into yellow. With the increase of temperature,the elongation at break and notched impact strength of the materials also exhibit a trend of increas-ing firstly and decreasing lastly. The dispersion of the IFR in PP is poor while using weak shear screw configuration and the material degrades while using concentrate strong shear screw configuration,when using dispersed multi-stage shear screw configuration,the elongation at break and notched impact strength are improved obviously,which increase by 80%and 40.5%separately compared with those of weak shear screw configuration. The best performance of the material is received by using the following process condi-tions:the feeding quantity is set as 60 kg/h,the screw speed is set at 500 r/min,the extrusion temperature is set at 180–200℃, and the screw configuration is designed as dispersed multi-stage shear type.