Relationship Between Temperature Rise With Heat Generation And Thermal Conduction Of The Rubber In The Compression Flexometer Test

The hysteresis property of rubber is important to rubber products such as tire and damper.In this paper, styrene butadiene rubber was chosen as base material, the effect of carbon block loading on the properties of the rubber were studied, particularly static viscoelastic property,heat generation, thermal conductivity and dynamic mechanic property. And thermal analysis mathematical model was established when the rubber block was in the steady-state, the relationship between the steady-state temperature rise in the center of the rubber blocks with different hardness in compression flexometer experiment and dynamic modulus, loss factor tanδ, dynamic compression strain ε0 as well as thermal conductivity is discussed.Then the orthogonal experiment design was adopted to evaluate the contribution of each factor to heat buildup in this study.Stress relaxation test, DSC, LFA, compressing flexometer experiment and RPA, DMA were employed to research the properties of the rubber, the results were shown as follows.With the increasing of carbon black loading, the interaction between carbon black and rubber was strengthen, so the bound rubber content and apparent cross-linking density were increased, the Mooney viscosity was also increased, curing speed was quickened, mechanical strength was strengthened, resilience was decreased, the Payne effect was become stronger,the stress relaxation effect was more apparent, the area enclosed by hysteresis loop was enlarged, compression temperature rise was increased, the heat capacity was reduced, the thermal diffusion coefficient and thermal conductivity were increased. With increasing the amount of carbon black, when the rubber was under high strain, the trend which was the storage modulus of G’ increasing with the increase of temperature was turned slow. In addition, because increasing temperature can improve the activities of the molecular chain segment, the results showed that with the increase of temperature, for a rubber, the resilience was increased, the storage modulus G’ was also increased, thermal diffusion coefficient was decreased, specific heat capacity and thermal conductivity were increased.In this paper, establishing thermal analysis mathematical model is depended on the fact that at steady-state conditions the total generated heat should be equal to the heat lost at the upper and the bottom as well as the side of the rubber block. The equation about temperature rise in the center was1)2(4tan32max 22’2022212wRh Rf G Rh TTTTww++=++-ldpe. From this equation,the steady-state temperature rise in the center of the rubber blocks in compression flexometer experiment was bound up with dynamic modulus, loss factor tanδ, dynamic compression strain ε0 as well as thermal conductivity. The values corresponding to specific temperature and strain of the rubber blocks in compression flexometer experiment was used to calculate temperature rise in the center of the rubber block with temperature estimation formula. The predicted temperature rise in the center of the rubber block under steady-state calculated by mathematical model were approached to practical testing values. The relative errors range from 1.98% to 9.81%, which are within 10%, thus proving the rationality of the derivation of the equation from experimental perspective. The origin of deviation between testing values and theoretical values was analyzed from the perspective of model approximation and actual operation. The results of orthogonal design analysis are shown as follows. The loss factor tanδis the most sensitive factor, and have a very significant impact on temperature difference(Tmax-Tw1). The effects of storage modulus G’ and dynamic compression strain ε0 are smaller than that of loss factor tanδ. Thermal conductivity λ is the most insensitive factor.