Reconstructing the mechanical response of polybutadiene rubber based on micro-structural evolution in strain-temperature space: entropic elasticity and strain-induced crystallization as the bridges

Strain-induced crystallization (SIC) in polybutadiene rubber (BR) was studied by in situ synchrotron radiation wide-angle X-ray diffraction (SR-WAXD) over a broad temperature range (-90 °C → 25 °C). Depending on the presence or absence of SIC and quiescent crystallization temperature, three temperature regions are divided. Detailed structural evolution is summarized in the strain-temperature space. Based on this micro-structural evolution information, the macroscopic mechanical response of BR, together with poly(isobutylene-isoprene) rubber (IIR) and natural rubber (NR), is reproduced based on Flory's and Plagge's theories. The origins of the mismatch of calculated and experimental stress-strain curves, especially in the large strain region, are discussed, and are mainly ascribed to the micro-macro connection approach and the network inhomogeneity.