STUDY ON THE PRESSURE-VOLUME-TEMPERATURE PROPERTIES OF SEALING RUBBER MATERIALS

To obtain accurate prediction of the performance of sealing rubbers and to optimize the processing parameters, the P-V-T data of three kinds of sealing rubbers: styrene-butadiene rubber, nitrile-butadiene rubber and nitrile-butadiene/chlorobutyl rubber composites, were studied. The parameters of Tait equations were calculated and compared with experiments. The results showed that the P-V-T relationship calculated by Tait equation was agreed well with the observation results. The value of parameter b(3) and b(4) were constants which mean the parameter B was a constant. The average residuals of P-V-T data between theoretical calculation and experimental values were all less than 0.02. It showed that the Tait equation can be used to describe the P-V-T relationship of these sealing rubber materials. Thermal expansion coefficients (alpha) and isothermal compressibility (beta) of the three rubbers were evaluated form Tait equations. The experimental results showed that in these three rubbers, NBR has the best size stability and NBR/CIIR has the worst size stability. Furthermore, the thermal expansion coefficients of NBR/CIIR would reduce significantly with the decrease of pressure. Through accurate description of the changes of alpha and beta with different pressures and temperatures for for the three sealing rubbers, a method with the function of guiding processing and applications research was obtained.