使用双螺杆挤出机制备高熔体强度PP的研究

Study on Preparation of High Melt Strength Polypropylene with Twin-Screw Extruder

使用双螺杆挤出机研究了聚丙烯(PP)在自由基引发下与反应单体二乙烯基苯发生挤出反应、制备高熔体强度PP的工艺条件和配方。结果表明:较高的螺筒温度不利于挤出反应,最佳螺筒温度为180,180,185,185,185,185,190,185,180℃(机头)。封闭螺筒第4区加料口,抗氧剂与其他原料从主加料口一起加入,会使产物熔体强度显著提高。螺筒尾部排气装置保持较高的真空度,能够使产物无气味。降低螺杆转速有利于支化反应的进行,产物的熔体强度明显提高。使用嵌段共聚PP料比均聚PP料更易于得到较高熔体强度的产物,引发剂2,5-二甲基-2,5-二(过氧化叔丁基)己烷(DHBP)的最佳质量分数为0.04%。

The processing conditions and formulas of high melt strength polypropylene(PP)were studied from extrusion reactive of PP and divinylbenzene in presence of free radical initiation by twin-screw extruder.The results show that higher temperature of screw barrel is not available for extrusion reactive.The optimum barrel temperature is 180,180,185,185,185,185,190,185,180℃(die-head).When the antioxidant and other raw materials are added together from the main feeding port,the feeding port of the fourth zone of barrel is closed,the melt strength of the product increases significantly.The product is odorless when the tail port of the screw barrel is kept at higher degree of vacuum.Reducing the screw speed is conducive to the branching reaction,and the melt strength of the product is significantly improved.The use of block copolymerized PP material is easier to obtain products with higher melt strength than homopolymerized PP material,and the optimum mass fraction of initiator DHBP is 0.04%.