复合硫化剂和硫化温度对氢化丁腈橡胶性能的影响

以硫黄与过氧化二异丙苯(DCP)为复合硫化剂,考察了DCP用量和硫化温度对氢化丁腈橡胶(HNBR)硫化特性及物理机械性能、压缩应力弛豫特性的影响。结果表明,随着DCP用量的增大,HNBR混炼胶的转矩差值增大,焦烧时间延长,正硫化时间先延长后缩短;随着硫化温度的升高,HNBR混炼胶的转矩差值先增大后减小,焦烧时间和正硫化时间均缩短;当DCP用量为7份、硫化温度为160℃时,HNBR硫化胶的物理机械性能和压缩应力弛豫特性最佳。     

苯甲酸釜残液全部回收的工艺开发利用

Benzoic acid residue is solid waste produced from the production of benzoic acid by oxidizing toluene. Because it contained important chemical raw materials such as benzoic acid, benzyl benzoate and fluorenone, it is necessary to recover them from the residue. In this work the technique featured with high efficiency evaporation and vacuum distillation was developed to obtain total recovery and utilization of the benzoic acid residue. By controlling the operation temperature at 260°C and the pressure of 16 kPa in the rising and falling film evaporators, heavy components separated efficiently from the residue can be polymerized and the light components consisting of 63% of the residue entered into a benzoic acid vacuum distillation column. Keeping the temperature of polymerization at (280±10)°C, coumarone resin was produced after adjusting the softening point according to the market re-quirements. Vacuum distillation was operated under the following conditions: top temperature at 186°C, top pres-sure of 16 kPa, bottom temperature at 240-250°C, reflux ratio being 3︰1. Benzoic acid of 98% purity was distilled out from the column as a side stream and the bottom product was crude benzyl benzoate. By the developed tech-nique, the benzoic acid residue was splitted into three products, benzoic acid, crude benzyl benzoate and coumarone resin without any surplus waste.