Abstract:

In this study， the effect of a catalyst DZ composed of a proportional mixture of 2，2'⁃dibenzoylaminodiphenyl disulfide （DBD） and zinc oxide （ZNO） on the desulfurization temperature of gum powders was investigated by using naphthenic oil as a desulfurization solvent. Based on this， the solubility of recycled gum in a trichloroethylene solution was taken as a core index， and the effects of catalyst admixture， desulfurization time， and gum⁃oil ratio were further evaluated to determine the optimal process parameters for the preparation of low⁃temperature desulfurization rubber powders. The mechanism and microscopic morphology of low⁃temperature desulfurization ^{of the gum powder were investigated by using scanning electron microscopy and Fourier⁃transform infrared spectroscopy. The results indicated that the catalyst DZ has a positive effect on the desulfurization of rubber powders， and the recycled rubber treated by low⁃temperature desulfurization exhibited reduced roughness alone with a more obvious ‘groove’ structure on the surface. This is advantageous to the engineering applications. The solubility of recycled rubber reached 76.9 % when the desulfurization temperature of rubber powders was lower than 160 ℃， which was close to the solubility of recycled rubber prepared by a traditional dynamic desulfurization method. This indicated that there was almost no adverse effect on the solubility of rubber powders by lowering temperature. The preparation parameters of low⁃temperature desulfurization rubber powders were determined to be a rubber powder/naphthenic oil mass ratio of 4/6， a catalyst DZ⁃doping amount of 3 wt%， a stirring rate of 450 rpm， a desulfurization time of 2 h， and a desulfurization temperature of 160 ℃.}

Key words: catalyst, scrap rubber, low temperature desulfurization, high solubility, microscopic morphology