轮胎胶应力诱导脱硫化及PE-HD动态交联热塑性弹性体制备

Devulcanization of Ground Tire Rubber Through Stress-induced Reaction and Preparation of Dynamic Vulcanized PE-HD Thermoplastic Elastomer

采用在废旧轮胎胶粉(GTR)与高密度聚乙烯(PE-HD)的熔融挤出过程中提高双螺杆挤出机螺杆转速的高剪切应力诱导方法,研究了双螺杆挤出机的螺杆转速、挤出反应温度及脱硫促进剂仲丁醇、烷基酚多硫化物(420或450)和正丁胺对轮胎胶脱硫共混物的凝胶含量、熔体流动速率、溶胶红外吸收光谱及轮胎胶脱硫共混物/三元乙丙橡胶(EPDM)动态交联热塑性弹性体力学性能的影响。结果表明:高转速同向双螺杆挤出机的高剪切作用可诱发废旧轮胎胶共混物中交联网络的断链和解交联反应,引起脱硫共混物凝胶含量的下降、未熔融凝胶颗粒尺寸的减小及熔体流动速率的增加;4种促进剂均具有明显促进脱硫反应的作用,其中450或正丁胺的促进脱硫效果较好,并引起脱硫共混物凝胶含量下降、熔体流动速率上升及动态交联热塑性弹性体力学性能的明显改善;当以正丁胺为脱硫促进剂时,最佳脱硫反应条件(240℃和1000r/min)下,脱硫共混物/EPDM动态交联热塑性弹性体的拉伸强度和断裂伸长率分别达到12.5MPa和440.6%。

The effects of screw rotation speed, extrusion temperature and the addition of devulcanizing agents （2-butyl alcohol, n-butyl amine, and alkyl phenol disulfide 420 or 450） on the various behavior of mixtures of ground tire rubber （GTR） and PE-HD were investigated. The high shear stress during melt extruding induced chain scission and oxidative degradation of the cross- linking network of the ground tire rubber, leading to the decrease of the gel content of the devulcanized blends, the increase of their melt flow rate, and the decrease of the size of gel grain in dynamic vulcanized PE-HD thermoplastic elastomer. The four devulcanizing agents all accelerated the devulcanization reaction during the extruding process, especially the alkyl phenol disulfide 450 and n-butyl amine achieved a better accelerating effect. In the best devulcanization condition （240℃ and 1000 r/min and in presence of n-butyl amine）, the tensile strength and elongation at break of a dynamically vulcanized devulcanized blends/EPDM thermoplastic elastomer reached 12.5 MPa and 440.6 %, respectively.