Tunable mechanical properties of vulcanised styrene-butadiene rubber by regulating cross-linked molecular network structures

Abstract

ABSTRACT Establishing the relationship between molecular structures and mechanical properties is of great significance for the structural design of vulcanised styrene-butadiene rubber (SBR). The molecular dynamics method was used to study the mechanical properties of cross-linked SBR with controlled network topology, and the corresponding molecular mechanism was analysed by the energy contribution during the stretching process. The results showed that the tensile stress of the end-linked network sample could be up to 20 times higher than that of the sample with dangling chains at an engineering strain of 1.4. Moreover, under the same fixed cross-linking degree, the tensile stress of the long-chain network sample was significantly higher than that of the short-chain network sample. This is because the molecular chains located in the main chain network will be highly oriented during the stretching process, while the proportion of highly oriented molecular chains is high in samples with end-linked networks or a large proportion of long chains. In addition, due to the limited relaxation of structural units, the end-linked network structure has good thermal stability.