热机械剪切脱硫过程中橡胶结构的变化

Change of Rubber Structure in Thermal Mechanical Shearing Devulcanization

采用自行组装的长径比为60∶1的双螺杆挤出机对废旧轮胎胎面胶粉热机械剪切脱硫。研究发现,通过热机械剪切的橡胶交联密度降低了62.35%,并且随着主机转速的增加,橡胶的交联密度进一步降低,微观结构也发生了变化。利用凝胶渗透色谱仪分析脱硫前后相对分子质量分布情况,发现随着主机转速的增加,橡胶溶胶的相对分子质量由大变小,相对分子质量分布宽度由宽变窄;用红外光谱仪对胶粉脱硫前后进行表征,结果表明,交联结构被破坏,生成了含硫基团的化合物,同时证实了线型天然橡胶(NR)的存在。根据脱硫前后橡胶官能团的变化以及键能与分子链的关系,研究了热机械剪切对橡胶结构的影响。

The mechanical shearing devulcanization of waste tire rubber( WTR) was conducted in a twin-screw extruder with aspect ratio of 60 /1 developed by Changzhou University. It is found that the crosslink density of the rubber reduces 62. 35% by mechanical shearing. With increase of the speed of the host,the crosslinking density of the rubber is further reduced. The molecular weight of rubber was analyzed by gel permeation chromatorgraphy. With increase of the speed of the host,the molecular weight of the rubber becomes less,molecular weight distribution becomes narrower.Fourier transform infrared spectra reveal that main component of the crosslinked structure was damaged to generate the sulfate ion and confirm the presence of linear natural rubber( NR). According to the changes of function groups and the relation between the chain structure and bond energy,the effect of mechanical shearing on the structure of rubber was speculated.