Influence of environmentally friendly curing system on properties of railway rubber pad

Improving the aging resistance and elasticity of rubber materials can increase the service life of rubber pads and reduce railway operation costs. The purpose of this work was to improve aging resistance, decrease compression set and ratio of dynamic stiffness to static stiffness (Rd/s) of railway rubber pads by using environmentally friendly accelerators N-t-butyl-2-benzothiazole sulfenimide (TBSI) and tetrabenzylthiuram disulfide (TBzTD). The influence of the curing system on the properties of rubber pads was assessed using multiple techniques. Compared to sulfur/tetramethylthiuram disulfide (TMTD) /N-cyclohexyl-2-benzothiazole sulfenamide (CZ), compression set of S/TBSI/TBZTD decreased to 29.5% from 35.7%, retention of elongation at break after hot air aging increased to 77.7% from 66.1%, and Rd/s decreased to 1.82 from 1.85. Thermogravimetry (TG) and derivative thermogravimetry (DTG) analysis indicated that maximum thermal decomposition temperature of TBSI/TBZTD was higher, which was the reason for the good aging resistance and low compression set results. Rubber processing analysis (RPA) demonstrated that the loss factor of TBSI/TBZTD was smaller. The rubber cured by TBSI/TBZTD had a higher crosslinking density and smaller loss factor, which decreased the Rd/s. This study provides a reference for preparing of environmentally friendly rubber pads with a low Rd/s and long service life. Compared with TT/CZ combination, combination TBSI/TBZTD binary accelerator system is environment-friendly. After the combination TBSI/TBZTD was used, the crosslinking density can be increased and the loss factor can be reduced. The properties of aging resistance, compression set and dynamic-static ratio of the rubber pad are improved. image