Improving reinforcement of natural rubber latex by introducing poly‐zinc dimethacrylate and sulfur vulcanizing system

Abstract In this work, zinc dimethacrylate (ZDMA) was employed to reinforce natural rubber latex (NRL) and a new process was introduced. Polymethacrylic acid was prepared by emulsion polymerization of methacrylic acid (MAA), then mixed with ZnO in a different mole ratio (ZnO/MAA) and the mixture was noted as PZDMA. It was added to NRL and a traditional sulfur vulcanizing system was adopted simultaneously. The mechanical test results show that compared with the sample “NR,” the tensile and tear strength are significantly improved by the addition of PZDMA. When 7 phr ZnO (NR‐7A) are loaded, it can reach 25.1 MPa and 62.8 N/mm, which are higher than “NR” by 52.0% and 104.6%, respectively. While the strength of the NRL film reinforced only with PZDMA is quite limited. Detailed analysis by Fourier‐transforms infrared spectroscopy, X‐ray diffractometers, scanning electron microscopy, thermogravimetric, and dynamic mechanical analysis revealed that PZDMA is successfully formed and dispersed uniformly in NRL, PZDMA acts as a nanoparticle and ionic cross‐linking agent, and the covalent cross‐linking network is formed by a sulfur vulcanizing agent. The dual cross‐linking network shows a synergistic effect on the reinforcement of NRL. The present work provides a process to reinforce NRL with adjustable mechanical properties.