Fiber-reinforced rubber composites (FRRC) are widely used in tires, hoses, conveyor belts and other fields. Currently, the industry heavily relies on the resorcinol-formaldehyde-latex (RFL) system to enhance interfacial adhesion performance of FRRC; however, both resorcinol (R) and formaldehyde (F) pose significant risks to human health and the environment. Thus, some two-step RF-free dipping systems have been developed to replace RFL system. Nevertheless, these complex two-step systems face challenges during industrialization. In this study, we proposed a novel one-step eco-friendly dipping system (PCGL) for polyamide66 (PA66)fibers. By using the new system, a solid transition bridge between PA66 fiber and rubber matrix can be formed, due to the bonding between PA66 and isocyanate, the interaction among polyacrylic acid resin, isocyanate and epoxy, the catalytic effect of triethanolamine, as well as the co-crosslinking of styrene-butadiene-vinyl-pyridine latex and rubber. The interfacial adhesion performance of PA66 fiber/rubber composites treated by PCGL with optimized ratio of epoxy groups/isocyanate groups can reach more than 90% of RFL level, meeting industry requirements for high interfacial bonding performance, while maintaining strength and safety of composites. The mechanism of largely enhanced interfacial adhesion was revealed through the analysis of modulus transition and co-crosslinking at the composite interface.
Fiber-reinforced rubber composites (FRRC) are widely used in automobile, aero tires, and conveyor belts , etc. In order to obtain high performance of FRRC, strong interfacial adhesion between fibers and rubber is a key. Resorcinol-formaldehyde-rubber latex (RFL) as the widely used dipping system in industry can do harm to human health and environment because of the release of resorcinol and formaldehyde in air. In this study, a new kind of eco-friendly dipping system for PA66 fibers was designed and successfully prepared, especially to meet the harsh service environment of aero tires. Such new dipping system is composed of the first coating of tea polyphenols (TP) on fiber surface through the hydrogen bonding between TP and PA66 fibers followed by the second coating with the mixture of glycerol triglycidyl ether (GTE), 2-ethyl-4-methylimidazole (MZ) and styrene-butadiene-vinyl-pyridine (VP) latex, in which the covalent bonding between TP and GTE, the crosslinking of GTE and the co-crosslinking of VP and NR matrix result in the formation of a solid transition bridge between PA66 fibers and NR matrix. By using such eco-friendly dipping system with optimized ratio of MZ/GTE, PA66 fibers/NR composites exhibit equivalent interfacial adhesion and aging stability as that using RFL system, while maintaining the strength and safety of composites. More importantly, PA66 fibers using the eco-friendly dipping system exhibit even better fatigue stability of interfacial adhesion after 46800 times of cyclic fatigue than that using RFL system. The relationship between the dipping layer structure and the interfacial adhesion of the composites was established.
危险品化学品经营许可证（带存储）