The study of ionic and entanglements self‐healing behavior of zinc dimethacrylate enhanced natural rubber and natural rubber/butyl rubber composite

Abstract

This study reported the self-healing behavior of natural rubber (NR) and NRbutyl rubber (IIR) composites, which was enhanced by graft-polymerization of zinc dimethacrylate (ZDMA) onto rubber chains. Using dicumyl peroxide (DCP) as the vulcanization agent formed a reversible covalent/ionic crosslinking supermolecular network. By controlling the vulcanization process, a reversible supramolecular network composed of covalent cross-linking, ionic cross-linking, and physical entanglement is obtained. Experiments shown that the self-repairing behavior of ionic bonds comes from the recombination of ionic clusters. Although the saturated backbone of IIR is hardly to provide ionic or covalent crosslinks, the addition of IIR can increase the degree of physical entanglements level of rubber and provide physical self-healing behavior. The entanglement healing is weaker than ionic cross-linking, but due to the better chain mobility, the multiple times healing ability of IIR introduced by entanglements is better than covalent or ionic bonds.

Dual X-ray- and Neutron-Shielding Properties of Gd2O3/NR Composites with Autonomous Self-Healing Capabilities

“…The reduction in the tensile strength and elongation at break of the self-healed NR composites in comparison to the original samples could be explained by the NR molecular chains in the uncut samples being originally cross-linked with a combination of covalent and ionic bonds, which resulted in relatively high tensile strength and elongation at break before the cut [ 46 ]. However, as the two damaged surfaces were gently pressed together and remained in contact for 60 min at room temperature (approximately 25 °C), a reversible ionic supramolecular network via the polymerization of ZDMA was able to recreate the sample through the mobility of NR molecular chains and, subsequently, restore some recoverable strength to the self-healed surfaces [ 47 ]. Nonetheless, the overall strengths of the self-healed samples were considerably lower than the original samples, with %Recovery values in the range of 3.7–9.1% ( Figure 9 c).…”

A new strategy for improving high‐temperature mechanical properties of HNBR/ZDMA composites through polymerization of ZDMA promoted by zinc methylmercaptobenzimidazole

“…In the HNBR/ZDMA composite, ZDMA can be initiated by peroxide to polymerize to form PZDMA, which includes the homo-polymerized PZDMA (homo-PZDMA) and the PZDMA grafted onto the HNBR chains (graft-PZDMA). 15,26 The ion pairs in PZDMA form ionic cluster structure owing to electrostatic interaction, and the ionic cluster structure strongly restrain the movement of adjacent rubber chains in the presence of graft-PZDMA. Meanwhile, the interaction between the graft-PZDMA and homo-PZDMA also limits the movement of the surrounding rubber molecular chains, leading to the construction of a new crosslinking network, namely ionic crosslinking network.…”

“…12,13 Rubber reinforced by ZDMA contains many ionic crosslinking bonds and nanoparticles, providing vulcanized rubber with unique mechanical properties. 14,15 In HNBR, ZDMA can polymerize to form poly(zinc dimethacrylate) (PZDMA) upon peroxide initiation. 16,17 However, only a small amount of PZDMA graft onto the HNBR molecular chains, and the interaction between HNBR and PZDMA primarily based on physical interaction is easy to be disrupted at high temperature, leading to a decrease in the high-temperature mechanical properties of HNBR.…”

Effect of Zn2+ salt bonding on thermo‐reversible self‐healing natural rubber

“…Many researchers encountered the lack by grafting the NR chains with zinc. 20 Recently, Xu et al 15 used ionic interactions to synthesize room temperature self-healing NR; however, no substantial evidence recorded that supramolecular networks were successfully integrated into the molecular networks. Thus, it causes the lack of a deeper understanding of rubber network formation and the correlation between the molecular structure of NR and the final properties, which limits further research.…”