“…[1][2][3] To meet the needs of practical application, vulcanization is one of the most important techniques for rubber products, which endows rubber materials with outstanding mechanical properties. 4,5 The difficulties in achieving the reversibility of sulfur crosslinking network lead to a large number of wastes and causes serious environmental pollution. How to realize the rearrangements of sulfur crosslinking network has been an unsolved problem in rubber industry.…”
Achieving the reversibility of conventional sulfur crosslinking network is beneficial for the sustainability of rubber products. However, sulfur crosslinking network has been considered as an irreversible network. Here, natural rubber (NR) is chosen as an example and trimethylsulfonium iodide (TMSI) can enable the transalkylation reaction between aliphatic sulfonium salts and the alkyl chains of vulcanized NR, which further realizes the rearrangements of sulfur crosslinking network in the elastomers. Such rearrangement reaction enhances the interfacial adhesion and fuse the fractured surface of vulcanized NR. Moreover, the rearrangements of sulfur crosslinking network induced by TMSI conforms to the characteristics of vitrimer network. This work solves the rearrangement problem of conventional sulfur crosslinking network, which is beneficial for the sustainability of rubber products.
“…[1][2][3] To meet the needs of practical application, vulcanization is one of the most important techniques for rubber products, which endows rubber materials with outstanding mechanical properties. 4,5 The difficulties in achieving the reversibility of sulfur crosslinking network lead to a large number of wastes and causes serious environmental pollution. How to realize the rearrangements of sulfur crosslinking network has been an unsolved problem in rubber industry.…”
Achieving the reversibility of conventional sulfur crosslinking network is beneficial for the sustainability of rubber products. However, sulfur crosslinking network has been considered as an irreversible network. Here, natural rubber (NR) is chosen as an example and trimethylsulfonium iodide (TMSI) can enable the transalkylation reaction between aliphatic sulfonium salts and the alkyl chains of vulcanized NR, which further realizes the rearrangements of sulfur crosslinking network in the elastomers. Such rearrangement reaction enhances the interfacial adhesion and fuse the fractured surface of vulcanized NR. Moreover, the rearrangements of sulfur crosslinking network induced by TMSI conforms to the characteristics of vitrimer network. This work solves the rearrangement problem of conventional sulfur crosslinking network, which is beneficial for the sustainability of rubber products.
“…DBTH could participate in the vulcanization of the NR matrix, and increased the crosslink density of NR, resulting in the increase of the tensile strength. 29 NR/CB-dS/0.2D had the similar mechanical properties to NR/CB.…”
The reversion during the curing and the poor thermal oxidative aging resistance of natural rubber are two main problems for its use as a tire tread. To solve the problems, a crosslinking agent, 1,6-bis(N,N 0 -dibenzyl thiocarbamoyl dithio)-hexane (DBTH), is added into natural rubber/carbon black composites.DBTH can increase the crosslink density, improve the mechanical properties and thermal oxidative aging resistance of the composites. The composites with DBTH can maintain good wet-skid resistance after thermal oxidative aging. When 0.2 phr DBTH is used to substitute 0.1 phr sulfur and 0.1 phr accelerator in a natural rubber/carbon black composite, the reversion during the curing is reduced and the DIN abrasion decreases by 6%, while the modulus and hardness of the composite keep close to the original. Besides, after thermal oxidative aging at 100 C for 48 h, the rate of change of stress at 300% strain of the composite decreases by 27% with the substitution of DBTH.
“…This is due to the fact that the protein in the natural latex is decomposed into amino acids after enzymatic hydrolysis, which is removed in layers after high-speed centrifugation 30 . The loss of protein will affect the vulcanization kinetics 31 , 32 , resulting in a weakening of the interaction force between the molecular chains 33 , an increase in the curl up-extension between the molecular chains and in heat dissipation. Figure 1 Temperature rise curve of FNR, CNR-1, CNR-2 and CNR-3.…”
Under high-speed strain, the thermogenesis performance of natural rubber products is unstable, leading to aging and early failure of the material. The quality of rubber latex and eventually that of the final products depends among others on the protein content. We found that when the protein is almost removed, the heat generated by the vulcanized rubber increases rapidly. After adding soy protein isolate to the secondary purification rubber, the heat generation of the vulcanized rubber is reduced, and the heat generation is the lowest when the added amount is 2.5–3.0 phr, which on account of protein promotes the construction of a vulcanization network and increases the rigidity of the rubber chain, resulting in a decrease in the potential frictional behavior of the rubber chain during the curl up-extension process.
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