Analysis of thermal ageing of elastomers -: Mechanical characterization of the network topography Part 2

Typical ageing effects on sulfur-crosslinked elastomers are the anaerobic restructuring of polysulfidic crosslinks and the thermal-oxidative induced scission of polymerchains. The consequences of this processes are changes in the properties of elastomers. With stress-strain-curves, which were interpreted in this paper with help of the non-affine tube model, we determined the crosslinking-modulus and the topological constraint-modulus. The use of statistic polymer parameters for the investigated styrolbutadien rubber, as the statistic segment length, make it possible to calculate the mechanically effective chain density and the chain fluctuation length (tube diameter). This allows conclusions on the developing of crosslinks and the mobility of chain segments, which are strongly influenced by chain scission.