Accelerated Storage Induced Structural Evolution in Natural Rubber: A Comparative Study of Two Constant Viscosity Treatment Methods

In order to compare the effects of current mainstream preparation methods for the constant viscosity natural rubber (CV) on structure during storage, this study used dry-mixing and latex-mixing methods to prepare the CV. The variation in mesostructure and microstructure of the CV prepared by the two constant viscosity treatment methods after accelerated storage for 48 h was analyzed. The result shows that both methods for preparing the CV can keep the macrogel content almost consistent after accelerated storage, while the microgel_>1μ content increased slightly. Meanwhile, both methods for preparing the CV can also stably maintain the molecular weight, the molecular weight distribution, and the shape of molecular chains after accelerated storage. However, the CV prepared by dry-mixing method demonstrated superior constant viscosity performance in Mooney viscosity (ML) and Wallace plasticity (P₀) during accelerated storage. The latex-mixing method for preparing the CV showed better advantage in preserving the number of branches per chain during accelerated storage.