Cure kinetics and morphology of natural rubber reinforced by the in situ polymerization of zinc dimethacrylate

Peroxide-cured natural rubber (NR) reinforced by zinc dimethacrylate (ZDMA) was prepared. The cocrosslinking action of ZDMA and the formation and evolution of the phase morphology induced by ZDMA during the curing process were systematically investigated. A curemeter and a differential scanning calorimeter were used to investigate the cure kinetics, and the kinetic parameters and the apparent activation energy were obtained. The phase morphology of the composites obtained from transmission electron microscopy revealed that separated nanophases of poly(zinc dimethacrylate) (PZDMA) existed in the rubber matrix. Covalent crosslinking, physical adsorption, and ionic crosslinking simultaneously existed in the composites, and they were determined with an equilibrium swelling method. On the basis of this, new microstructure models of NR/ZDMA composites and ionic crosslinking were put forward.