有限変形下における加硫SBRの力学的性質

概要

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The stress relaxation properties of SBR vulcanizates, those unfilled and those filled with carbon, under orthogonal-biaxial deformation, were subjected to observation in a region from 3.4 to 10 of I1 values where I1 was invariant of deformation tensor, and the contour maps of ∂W/∂I1 and ∂W/∂I2 were obtained as functions of time t. The following results have been obtained. The time dependence of both ∂W/∂I1 and ∂W/∂I2 of the unfiilled SBR vulcanizate are very similar within experimental error, but in the case of the filled SBR, those are quite different. In the filled SBR, the relaxation rate of ∂W/∂I1 decreases with increase in I1, and on the contrary, the rate of ∂W/∂I2 increases with increase in I1. The shape of ∂W/∂I1 surface of the filled SBR is similar to that of the unfilled SBR, but the former is on a considerably higher level than the latter, while the shape of ∂W/∂I2 surface of the filled SBR is different from that of the unfilled SBR. The values of ∂W/∂I1 and ∂W/∂I2 in the uniaxial deformation are obtained by the extrapolating method using the biaxial data. It is shown that the values of ∂W/∂I1 and ∂W/∂I2 in the uniaxial deformation decrease with increase in deformation. In this fact is suggested that strain energy function W cannot be estimated by Mooney-Rivlin plot, and that the constants C1 and C2 obtained from the plot are almost of no significance.
社団法人日本材料学会の論文