Preparation And Properties Of Self-healing Natural Rubber Composites

In the field of materials,natural rubber(NR),as a natural renewable resource,occupies an important position in the world due to its low price and excellent comprehensive performance.However,natural rubber will suffer various damages during processing or use,which reduces the mechanical properties of the product and shortens the service life of the product.The large amount of waste generated after the use of natural rubber(NR)products will also cause environmental pollution and waste of resources.Self-healing natural rubber materials came into being,which can make natural rubber(NR)have self-healing properties through reversible covalent bonds or non-covalent bonds,and realize the repair of damaged parts of natural rubber.The introduction of ion association is one of the effective ways to realize the self-healing properties of rubber.In this paper,by adding sorbic acid(SA)/zinc oxide(ZnO)in the natural rubber(NR)mixing process to generate zinc sorbate(ZDS)in situ,and using peroxide initiators to graft ZDS onto the NR,The zinc ion and the carboxylate anion on the main chain of the NR molecule form an ionic bond to prepare an NR-ZDS composite material with an ionic cross-linking network structure.The formation of ZDS was confirmed by XRD and FTIR,and the influence of SA/ZnO molar ratio on the vulcanization characteristics,swelling characteristics and self-healing properties of NR-ZDS composites was studied.The results showed that zinc sorbate(ZDS),which was generated in situ from sorbic acid and zinc oxide in the NR-ZDS composite,was grafted onto the natural rubber matrix;when the molar ratio of the two was more than 2:1,zinc oxide was used as a reinforcing agent Dispersed in the matrix of NR-ZDS composite material;when the SA/ZnO molar ratio is 2:1.4 and the vulcanization time is 1 min,the self-repairing efficiency of NR-ZDS composite material is 93%,the tensile strength is 0.85 Mpa,the comprehensive mechanical properties are good,and the self-repairing efficiency is high;by controlling the vulcanization time and SA/ZnO molar ratio,the mechanical properties and self-repairing properties of NR-ZDS composites can be controlled.In this paper,epoxidized natural rubber(ENR)with different degrees of epoxy was prepared by introducing epoxy groups into natural rubber(NR).Then use the initiator DCP to add methacrylic acid(MMA)/zinc oxide(ZnO)during the mixing process of ENR-25 to generate zinc methacrylate(ZDMA)in situ,which is grafted onto the ENR macromolecular chain to prepare The ENR-ZDMA composite material with a dual network structure of ionic cross-linking network and covalent cross-linking network.The results show that: when the vulcanization temperature is 140 ?,the vulcanization time is 3min,and the molar ratio of MMA/ZnO is 2:1.3,the tensile strength before self-healing of ENR-ZDMA composite is 1.89 Mpa,and the self-healing efficiency is 92%.The performance is the best;by controlling the vulcanization time and the MMA/ZnO molar ratio,the mechanical properties and self-healing properties of ENR-ZDMA composites can be controlled.