Swelling behavior of rubber in the hydrocarbon liquids

The swelling behavior of natural rubber was investigated using the immersion and weighing technique to verify the transport mechanism and property of hydrocarbon solvent, which is ready for the study on the compatibility of endothermic hydrocarbon fuel and rubber. Natural rubber was vulcanized by sulfur vulcanization system which was filled with fast extruded furnace black and SiO₂, peroxide curing system and a mixture consisting of sulfur and peroxide system. The sulfur vulcanization system filled with fast extruded furnace black showed the lowest solvent sorption and the peroxide curing system showed the highest. The influences of the cross-linking density, solvent molecule and temperature were studied, and the diffusion results were also analyzed using Fickian model. The results deviated from the Fickian model and the diffusion was anomalous in nature. Moreover, the diffusion coefficient increased when the molar volume, molecular weight and the length of molecular chain increased. Weight gain of the rubber and diffusion decreased with the crosslinking density increasing. It was found that p-xylene and propyl benzene could swell the rubber more easily than alkanes in the experiment. The diffusion and sorption of n-decane through sulfur vulcanization system filled with SiO₂ was studied in the temperature interval 18-60℃. It was found that the solvent sorption increased with the temperature.