Facile Construction of Zn²⁺‐Carboxyl Salt‐Bonding as Sacrificial Unit in EPDM Rubber toward Mechanical and Sealing Resilience Performance Enhancement

Abstract

In view of the facile reaction between carboxyl groups and zinc oxide (ZnO), Zn2+‐carboxyl salt‐bonding is constructed in ethylene propylene diene monomer (EPDM) rubber system by grafting reaction of glutamic acid (Glu), serving as sacrificial unit endowed EPDM‐g‐Glu/ZnO sample with excellent reprocessing and recycling ability. Through reaction of ZnO/methacrylic acid (MAA), EPDM‐g‐Glu/zinc dimethacrylate (ZDMA) composite is further prepared by in situ formation of ZDMA, and ZDMA is rapidly polymerized to form poly‐ZDMA (PZDMA) containing massive Zn2+‐carboxyl ion pairs once vulcanized, which exhibits fuzzy interface with the matrix. Relative to EPDM/ZDMA, the higher polymerization degree of ZDMA is achieved with the reduction of the size of PZDMA clusters, demonstrating the improvement of interfacial bonding, which results in the formation of a developed crosslinking network structure for EPDM‐g‐Glu/ZDMA. The mechanical strength, fracture toughness, and hysteresis loss of EPDM‐g‐Glu/ZDMA‐40% show a significant increase in comparison with EPDM/CB‐40% and EPDM/ZDMA‐40%, meanwhile the relatively lower compression set and slower contact stress relaxation are achieved by energy dissipation mechanism of preferential rupture of Zn2+‐carboxyl salt‐bonding before breakage of covalent bonds during compression aging process, revealing the effective enhancement of durable sealing resilience performance.

Recyclable, Self-Healing, and Highly Thermal Conductive Natural Rubber Nanocomposites Enabled by a Dynamic Covalent Network with Carboxylated Boron Nitride Nanosheets

“…The white nanoparticles and small aggregates involved with BN-COOH and GO were observed. It was evident that the number and size of the BN-COOH/GO nanoparticles reduced with the increase of recycling times and the fractured surface showed relatively smooth features, suggesting that more BN-COOH had been reacted with ENR to form a β-hydroxyl ester bond and BN-COOH was further refined after recycling, which could participate in the reconstruction and rearrangement of the exchangeable crosslinking bonds during recycling …”

“…It was evident that the number and size of the BN-COOH/GO nanoparticles reduced with the increase of recycling times and the fractured surface showed relatively smooth features, suggesting that more BN-COOH had been reacted with ENR to form a β-hydroxyl ester bond and BN-COOH was further refined after recycling, which could participate in the reconstruction and rearrangement of the exchangeable crosslinking bonds during recycling. 41 The dynamic β-hydroxyl ester crosslinking was expected to exhibit the self-healing behavior. The ENR/BN-COOH/GO sample was cut into two pieces and then directly contacted at their freshly cut interfaces at room temperature, and the merging interface was observed without any external stimuli for the sample after 5 min by using an optical microscope, indicating the dynamic exchange and rearrangement of the βhydroxyl ester bonds at the healed interface.…”

The mechanical and thermal properties of natural rubber/zinc methacrylate composites by latex compounding techniques

“…The other is zinc oxide (ZnO) and methacrylic acid (MAA) is introduced and undergo a neutralization reaction in the mixing process and ZDMA is generated in situ (“in situ reaction” process). [ 23 ] Commercialized ZDMA has a certain degree of decomposition in the air and produces a pungent odor, and could occur self‐polymerization in a certain degree, which are potential hazards to human health and environmental safety. At the same time, ZDMA is a kind of polar unsaturated carboxylate, which is easy to aggregate in non‐polar rubber, resulting in poor dispersion, [ 24 ] so in comparison the in‐situ generation method shows an advantage to some extent.…”

Covulcanizing of Fluorinated Carbon Black Ability with Styrene Butadiene Rubber Combining Enhanced Low- and Wide-Frequency Microwave Absorption

“…However, lack of noncovalent interactions between the filler and the rubber matrix was the main reason that limited further mechanical enhancement in rubber composites. − Therefore, surface treatment of fillers was an important strategy to optimize the interfacial connection of the composite. Taking carbon black as an example, it is the most common filler used in rubber reinforcement and has been consumed for a large amount per year. , Due to the porous and fractal structure of carbon black, significant physical entanglement of rubber molecule chains always occurs with a carbon black filler with receptible interfacial combination. − With increasing demands in the field of rubber composites, it was gradually found that simple physical entanglement was not enough to meet further optimization of rubber products; hence, surface treatment of carbon black is also needed to induce stronger interfacial combination of the composite, like chemical grafting, − etching, , and surface coating. , However, due to the high proportion in the formula of the rubber product, surface treatment of carbon black needs rapidity; thus, complex chemical processing is not suitable in industrial application. In addition, strategies like etching and surface coating still stay in the stage of enhancing interfacial wettability between carbon black and the rubber matrix; hence, an efficient surface treatment strategy is still needed in carbon black pretreatment.…”