抄録
The degradation of SBR vulcanizates subjected to outdoor-exposure testing in the Arizona desert for one year was studied. The dynamic viscoelasticity of sample sheets of 2mm thickness, and sliced thin films of 0.2mm thickness was measured.
SEM images of the surface and sheet cross sections were also taken in order to observe microscopic changes in the samples. Changes in dynamic viscoelasticity, due to the weathering test, were observed to be confined within a thin surface layer on the sunshine side. Nevertheless, the exposed sheet exhibited a large decrease in tanδ. This appears to be attributable to the large increase in E′ compared to the small increase in E" in the surface layer. A theoretical analysis taking into account of the variation in the value of dynamic viscoelasticity with sample thickness exhibited good agreement with the experimental data.
