Preparation of lignin‐based filling antioxidant and its application in styrene‐butadiene rubber

Abstract

A novel filling antioxidant (Lig‐g‐RT) to improve the mechanical properties and antiaging performance of styrene‐butadiene rubber (SBR) composites was prepared by grafting antioxidant intermediate p‐aminodiphenylamine (RT) on the surface of lignin via the linkage of silane coupling agent. Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) measurements confirmed that RT was successfully grafted on the surface of lignin to produce the functionalized Lig‐g‐RT which shows a better thermal stability than lignin. Compared with SBR/lignin composite, the SBR/Lig‐g‐RT composite using latex co‐precipitation method exhibits a much better filler dispersion, which contributes to the maintain of the physical mechanical properties of SBR vulcanizates. Moreover, the SBR/Lig‐g‐RT vulcanizate exhibits less chemical crosslink concentration and higher entanglement density than SBR/lignin vulcanizate according to the Mooney–Rivlin model analysis. In addition, the stabilizing effect of lignin/Lig‐g‐RT on the carbon‐black filled SBR vulcanizates is comparable with that of commercial antioxidant N‐1,3‐dimethylbutyl‐N′‐phenyl‐p‐phenylenediamine (4020), especially the SBR vulcanizate filled with 10 phr Lig‐g‐RT obtains the optimum thermo‐oxidative aging properties. This functionalized Lig‐g‐RT not only provides an intramolecular synergistic antiaging effect for SBR vulcanizates and an improvement of filler dispersion, but greatly extends the comprehensive utilization of industrial lignin.

Recent Advances of Lignin Functionalization for High-Performance and Advanced Functional Rubber Composites

“…The AL also promoted the activation of sulfur to increase the curing rate and cross-link density of rubber, improving the fatigue resistance for NR composites. Zhao et al grafted p -aminodiphenylamine (RT) onto lignin molecules via a bridge of silane coupling agent. The stabilizing effect of the resulted antioxidant Lig- g -RT on the SBR vulcanizates was comparable to that of commercial antioxidant 6PPD, especially the SBR vulcanizate filled with 10 phr of Lig- g -RT showed the optimum antithermo-oxidative properties.…”

“…Possible antioxidization mechanism of the SBR/Lig- g -RT vulcanizate. Reproduced with permission from ref . Copyright 2021 Wiley.…”

Amine-Functionalized Lignin as an Eco-Friendly Antioxidant for Rubber Compounds

“…In this context, amine-functionalized lignin (AL) can be a promising candidate for overcoming the drawbacks of lignin. The aliphatic amine functional groups grafted onto a lignin surface are known as one of the most effective groups for removing ozone and free radicals. , Therefore, AL may impart significantly enhanced aging resistance to rubber compounds compared to that of KL through its radical-scavenging effect. − Furthermore, amine-based antioxidants have been reported to open the octatomic rings of S 8 through direct nucleophilic attack, thus accelerating the vulcanization of rubber and generating more active sulfonating agents for rubber curing. − This reaction offers the possibility of the antioxidant to participate in the vulcanization reaction with a mechanism similar to that of the accelerator, and it can improve the compatibility of the antioxidant with rubber by maintaining chemical bonds with the rubber chains even after the reaction is completed.…”

Antioxidative Behavior of an Eco-Friendly Chitosan-Based Biomass Macromolecular Antioxidant for Styrene–Butadiene Rubber (SBR)/Silica Composites

“…Generally, the addition of antioxidants during rubber compounding can delay the aging process of rubber materials and extend their service life. , But most of the traditional rubber antioxidants are small molecular organic compounds, which are easily prone to migration from the polymer matrix during the process and usage. Many studies showed that the migration of antioxidants not only reduces the anti-aging effect of antioxidants but also causes environmental pollution. , In order to overcome the shortcomings of traditional small molecular antioxidants, some effective strategies have been proposed, such as preparing macromolecular antioxidants, reactive antioxidants, and inorganic particle-immobilized antioxidants. − Among them, macromolecular antioxidants have attracted wide attention due to their low diffusion rates, excellent extraction resistance, and superior thermal stability. − Generally, there are two main methods for preparing macromolecular antioxidants. One way is through the polymerization of functionalized antioxidant monomers.…”