轮胎胶脱硫共混物增韧聚丙烯的影响因素

Effect of Ground Tire Rubber Devulcanized Blends on Mechanical Properties of Toughening Polypropylene

在轮胎胶粉与热塑性弹性体(POE)共混物的熔融挤出过程中添加有机醇类化合物作为脱硫反应促进剂,研究双螺杆挤出机的螺杆转速和挤出反应温度对轮胎胶脱硫共混物的凝胶含量、溶胶分子链结构及增韧PP材料力学性能的影响。实验结果表明:随着双螺杆挤出机螺杆转速的增加或挤出反应温度的升高,轮胎胶粉颗粒所受到的机械剪切应力作用或热能作用均明显增强,强烈的剪切应力和热能可引发轮胎胶中交联网络的断裂、降解或解交联反应发生,引起脱硫共混物中凝胶含量明显下降、凝胶粒子尺寸明显减小以及与PP材料相容性明显改善。添加有机醇-1化合物作为脱硫反应促进剂时,有利于脱硫反应的进行,有利于脱硫产物中双键的保护,并引起脱硫共混物凝胶含量进一步下降、凝胶颗粒尺寸进一步减小和增韧PP材料力学性能进一步提高。在240℃条件下添加有机醇-1化合物进行脱硫反应,当脱硫反应螺杆转速由400 r/min增加至1 200 r/min时,所得脱硫共混物增韧PP材料(PP/DGTR/POE=70/24/6)的缺口冲击强度可由17.4 kJ/m2提高至34.4 kJ/m2,并且引起此共混材料拉伸强度、断裂伸长率、弯曲模量及熔体指数的明显增大。

The devulcanization reaction of ground tire rubber （GTR） performed during melt extruding of the mixture of GTR with polyethylene octene elastomer （POE） through a high shear stress-induced reaction by increasing the screw rotation speed and reaction temperature was investigated. The effect of organic chemical alcohol-1 on the devulcanization reaction and the mechanical properties of the devulcanized blend toughening polypropylene were studied. The results showed that the high shear stress came from the increasing of the screw rotation speed and reaction temperature. The strong stress-induce could cause the chain scission,the gel content of the devulcanized blend （DGTR/POE） decreasing and break up the cross-linking network of the GTR. Adding some organic chemical alcohol-1 as a devulcanized promoting agent could accelerate the devulcanization of the waste tire rubber and help to protect the double bonds in the sol chains and decrease the gel content and the size of the unfused gel particles in the devulcanized blend. As a result,in presence of alcohol-1 as an additive and at 240 ℃ condition, when the screw rotation speed increased from 400 r/min to 1 200 r/min, the impact strength of the devulcanized blend toughening polypropylene （ PP/DGTR/POE = 70/24/6） increased from 17.4 kJ/m^2 to 34.4 kJ/m^2. Meanwhile, the tensile strength,elongation at break,flexural modulus and melt flow rate of the toughened polypropylene were obviously increased.