Accelerator and zinc-free prevulcanized latex based on natural rubber-bearing benzyl chloride groups

The present study aimed to prepare prevulcanized latex from modified natural rubber (NR) latex, graft copolymers of natural rubber and poly(vinylbenzyl chloride), NR-g-PVBC.The prevulcanized latex was prepared by heating NR-g-PVBC latex in the presence of adipic acid dihydrazide (ADH).The study showed that the tensile strength of the NR-g-PVBC films with ADH was significantly higher than that without ADH.Interactions of NR-g-PVBC with ADH were further investigated using X-ray photoelectron spectroscopy (XPS).Higher storage modulus (E′) in the rubbery plateau region was also observed for the films with ADH than that without ADH.These results corroborated that the crosslinking reaction occurred in the film with the addition of ADH.It was found that the optimal prevulcanization time was 20 min at 55 °C.After that, the effect of storage on the tensile properties of the prevulcanized latex was studied.Atomic force microscopy (AFM) analysis was performed to follow changes in the surface morphology of films obtained from the prevulcanized latex.A zeta potential value of -37.83 was observed for the prevulcanized latex after being stored for 60 days.Therefore, the present study demonstrated that grafting poly(vinylbenzyl chloride) onto NR particles offered an opportunity to prepare a new type of prevulcanized latex.This new system was accelerator-free and zinc-free, considered more environment-friendly than a sulfur-prevulcanization system.