利用超临界二氧化碳流体脱硫再生丁基橡胶

研究了硫黄硫化的丁基橡胶在超临界二氧化碳流体辅助下的脱硫降解行为,讨论了脱硫工艺的条件,并通过凝胶渗透色谱、核磁共振、差示扫描量热等对丁基再生胶的结构和性能进行了考察。结果表明,在二氧化碳的超临界状态下丁基橡胶的脱硫降解更加充分。脱硫的最佳工艺条件为:反应温度180℃,反应压力14.1 MPa,脱硫剂二苯基二硫的用量为橡胶质量的8%;经过120 min脱硫反应后丁基再生胶中溶胶的质量分数为98.5%。在有热降解和脱硫剂参与的脱硫反应的共同影响下,丁基再生胶中溶胶的数均分子量降至原胶的40%左右;再生胶主链上接枝了部分脱硫剂的苯环;硫化和脱硫过程中在接枝于主链上的极性基团的影响下,再生胶中溶胶主链双键氢的振动峰几乎消失,但再生胶的玻璃化转变温度并没有明显变化。

Desulfurization of sulfur-cured butyl rubber by using supercritical carbon dioxide

The sulfur-cured butyl rubber was desulfurized in supercritical carbon dioxide with diphenyl disulfide(DD) as a desulfurizing agent,the effect of processing condition on desulfurization was investigated,and the structure and properties of reclaimed butyl rubber were characterized by gel permeation chromatography,proton nuclear magnetic resonance spectroscopy,differential scanning calorimetry.The results showed that in supercritical carbon dioxide,the sulfur-cured butyl rubber could be fully desulfurized and degradated.The optimal processing condition was found out: temperature 180 ℃,pressure 14.1 MPa,mass fraction of DD in rubber 8%.Under this condition,the mass fraction of sol component in reclaimed rubber could achieve 98.5% after the cured butyl rubber was desulfurized for 120 min.With the joint action of thermal degradation and desulfurized by DD,the number-average molecular weight of the sol component would decreased to about 40% of the virgin rubber′s.Owing to the effect of polar groups grafted onto backbone during sulfurization and desulfurization,such as benzene ring in DD,the vibration absorption peak for the doule bond hydrogen on the backbone of sol component almost disappeared,but the glass transition temperature for reclaimed rubber had no obvious change.