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In order to solve the problem that alumina based ceramic core is not easy to remove core, a certain amount of PA66 fiber was added as pore forming material to prepare porous aluminum based ceramic core by hot pressing. The influence of PA66 fiber content on the porosity, room temperature bending strength and sintering shrinkage of aluminum based ceramic core was investigated, and the mechanism of PA66 fiber content on the porosity of aluminum based ceramic core was analyzed. The results show that the porosity of alumina based ceramic core is significantly increased by adding PA66 fiber, and the sintering shrinkage of the core is effectively blocked. With the increase of PA66 fiber, the porosity of alumina based ceramic core is increased, and the bending strength and line shrinkage rate at room temperature are decreased. When the PA66 fiber content is 0.9%(mass fraction), the porosity of the aluminum based ceramic core is 41.14%, the bending strength is 15.33 MPa, and the linear shrinkage rate is 0.418%.

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. [Display omitted] • A novel one-step eco-friendly dipping system was developed for PA66 fibers. • The adhesion of this new dipping system reaches 90% of traditional RFL system. • It overcomes complex process and high cost of current two-step RF-free systems. • It shows equal interfacial adhesion with current two-step RF-free systems. • The mechanism of its high interfacial adhesion performance was revealed. [ABSTRACT FROM AUTHOR]

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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. [Display omitted] • A new kind of eco-friendly dipping system for PA66 fiber cords was developed. • The new dipping system shows equivalent adhesion effect as that using RFL. • The new dipping system exhibits better fatigue stability than that using RFL. • The dipping layer structure and interfacial adhesion relationship was established. [ABSTRACT FROM AUTHOR]