In this work, ground tire rubber (GTR) was thermo-mechanically treated in the presence of styrene-butadiene-styrene (SBS) copolymers. During preliminary investigation, the effects of different SBS copolymer grades, the variable content of SBS copolymer on the Mooney viscosity, and the thermal and mechanical properties of modified GTR were determined. Subsequently, GTR modified by SBS copolymer and cross-linking agents (sulfur-based system and dicumyl peroxide) was characterized by assessment of rheological, physico-mechanical, and morphological properties. Rheological investigations showed that linear SBS copolymer, with the highest melt flow rate among studied SBS grades, was the most promising modifier of GTR, considering processing behavior. It was also observed that an SBS improves the thermal stability of the modified GTR. However, it was found that higher content of SBS copolymer (above 30 wt%) does not bring any effective changes and, for economic reasons, is inefficient. The results showed that samples based on GTR modified by SBS and dicumyl peroxide have better processability and slightly higher mechanical properties compared to samples cross-linked by a sulfur-based system. This is due to the affinity of dicumyl peroxide to the co-cross-linking of GTR and SBS phases.

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Processing, Mechanical and Morphological Properties of GTR Modified by SBS Copolymers

The disposal of scrap rubber, represented by retired tires, has achieved industrial achievements, but the handling of brass-coated steel wire as a structural reinforcement in retired tires has received little attention. A feasible and efficient method of acquiring economical resources is proposed to extract copper and zinc (Cu-Zn) from brass-coated steel wire. With 20% ammonia, 10% hydrogen peroxide, and a liquid-solid ratio of 10, the brass coating almost completely dissolved in 5 minutes. This technique may remedy the challenge of weak dissolving efficiency brought on by the dual phase microstructure of brass. Electrochemical measurements and density functional theory (DFT) simulations assist in verifying that hydrogen peroxide decreases the resistance of the corrosion and that OH- and O-2 in solution are the main contributors to the dissolution. In addition, the AH effectively enhances the corrosion of the α phase in brass, which is notably evident in comparable works. This effective strategy broadens the application of retired tires and provides a new method for extracting Cu-Zn resources. 

/pdf/enhancement-of-resource-recovery-from-retired-tires-vkc1yo1a.pdf

Enhancement of resource recovery from retired tires: Extraction of copper and zinc resources

Research on the mechanical properties of polyvinyl alcohol-modified waste rubber-filled cement paste using digital image correlation technology

Excessive accumulation of rubber waste necessitates the need to revisit the effectiveness of the existing rubber waste management system. This review provides an overview of the legislative frameworks, techniques, challenges, and trends of rubber waste management in various countries. The 4R (reduce, reuse, recycle and recover) framework applied in waste management system in some countries appears to be viable for the processing of rubber waste. Certain countries especially some of the European Union (EU) members have implemented extended producer responsibility (EPR) system to manage the collection of rubber waste, particularly used tires. The processing of rubber waste in each level of the 4R hierarchy was then discussed, with detailed elaboration on the most practiced 'R', recycling which encompasses the direct recycling of products, as well as material recycling via physical and/or chemical means. The challenges faced in the implementation of rubber waste management system in different countries were highlighted and recommendations for a more sustainable rubber consumption were provided at the end of this review. 

/pdf/4r-of-rubber-waste-management-current-and-outlook-3tl7zptu.pdf

Thiam-Young Koh

Papers

4R of rubber waste management: current and outlook