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The addition of rubber powder (RP) to natural rubber (NR) matrix using the dry mixing method leads to uneven distribution and poor interface bonding while the wet mixing method is not feasible due to the hydrophobic nature of the RP surface. To address this issue, we developed a method for producing RP with weakened hydrophobicity on the surface by high‐pressure waterjet and successfully achieved even distribution of the waterjet‐produced rubber powders (WPRPs) in NR and strong interface adhesion between WPRPs and NR by the wet mixing method. The properties of NR/WPRP composites were tested and characterized carefully. When adding 6 phr of 140‐mesh WPRPs in the NR matrix, the tensile strength and elongation at break of the NR/WPRP composites were 30.2 MPa and 627.2%, respectively, which were 4% and 7% higher than NR without WPRPs. Moreover, the anti‐abrasion property of the NR/WPRP composite was also strengthened by the addition of WPRPs. Our findings demonstrate that recycling waste rubber through a reasonable recycling method can not only reduce material waste and alleviate environmental pollution but also enhance the performance of the raw rubber, which offers significant economic benefits. [ABSTRACT FROM AUTHOR]

Low-temperature mechanical chemical devulcanization is a process that can produce reclaimed rubber with exceptional mechanical properties. However, the inadequacy and low efficiency of the devulcanization have significantly restricted its application. To address the issues, alcoholic amines, including hydroxyethyl ethylenediamine (AEEA), ethanolamine (ETA), and diethanol amine (DEA), are utilized as devulcanizing agents to promote the devulcanization process. Careful characterizations are conducted to reveal the devulcanizing mechanism and to depict the performances of reclaimed rubbers. Results show that the amine groups in the devulcanizing agents can react with sulfur after the crosslink bonds are broken by mechanical shear force, thus blocking the activity of sulfur and introducing hydroxyl groups into the rubber chains. The incorporation of alcoholic amines can enhance the devulcanizing degree and devulcanizing efficiency, reduce the Mooney viscosity, and improve the mechanical and anti-aging performance. When using DEA as the devulcanizing agent, the sol content of reclaimed rubber increases from 13.1% to 22.4%, the devulcanization ratio increases from 82.1% to 89.0%, the Mooney viscosity decreases from 135.5 to 83.6, the tensile strength improves from 14.7 MPa to 16.3 MPa, the retention rate of tensile strength raises from 55.2% to 82.6% after aging for 72 h, while the devulcanization time is shortened from 21 min to 9.5 min, compared with that without using alcoholic amines. Therefore, alcoholic amines exhibit remarkable advantages in the devulcanization of waste rubber, thus indicating a promising direction for the advancement of research in the area of waste rubber reclamation. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT), as reinforcing agents in natural rubber (NR), has gained a large amount of consideration due to their excellent properties. Uniform dispersion of CNT is the key to obtaining high-performance NR nanocomposites. In this contribution, a novel ultrasonic grinding dispersion method of CNT with waterjet-produced rubber powder (WPRP) as a carrier is proposed. Microscopic morphologies show that a Xanthium-like structure with WPRP as the core and CNTs as the spikes is formed, which significantly improves the dispersion of CNT in the NR matrix and simultaneously strengthens the bonding of the WPRP and NR matrix. With the increase in the WPRP loading, the Payne effect of CNT/WPRP/NR composites decreases, indicating the effectiveness of the dispersion method. The vulcanization MH and ML value and crosslinking density increase with the increase in the WPRP loading, whereas the scorch time and cure time exhibit a decreasing trend when the WPRP loading is less than 15 phr. It is found that the CNT/WPRP/NR composites filled with 5 phr WPRP have a 4% increase in 300% modulus, a 3% increase in tensile strength, while a 5% decrease in Akron abrasion loss, compared to CNT/NR composites. [ABSTRACT FROM AUTHOR]