Peijin Weng’s research while affiliated with South China University of Technology and other places

The wet traction, rolling resistance and abrasion resistance have rarely been improved simultaneously in tread rubbers, which is regarded as “magic triangle” in tire industry. Recently, we have demonstrated that phosphoniums are effective in lowering rolling resistance of tread via catalyzing the interfacial silanization. In addition, incorporating the C5/C9-based petroleum resin into tread formulation is a well-established technology toward high wet traction. Accordingly, we aim to solve the “magic triangle” dilemma by using phosphonium-modified petroleum resin (PSR), which is prepared through a two-step reaction. PSR is incorporated into the silica-filled styrene-butadiene rubber (SBR) composites with bis [3-(triethoxysilyl)propyl] tetrasulfide (TESPT). Due to the electrostatic interaction between PSR and silica, the dispersion of silica is improved. Moreover, PSR exhibits catalytic effect on the interfacial silanization, leading to the improvement of interfacial interactions. With incorporation of 2 phr of PSR, the tan δ at 0 °C and abrasion loss of the rubber composite are increased by 19% and decreased by 28%, respectively, which suggests that the wet traction and abrasion resistance are increased. The tan δ at 60 °C of the rubber composite is decreased by 14%, indicating that the rolling resistance is decreased. In addition, the overall excellent “magic triangle” performance of a typical tread rubber is also demonstrated by incorporating PSR, indicating that PSR has great potential in practical applications. We envisage that this study provides a new solution for high-performance tread rubber for green tires.

Silane coupling agent has been used for ages to improve the performances of silica-filled rubber composites. To improve the degree of silanization of silica, ionic liquids (ILs) as a catalyst are incorporated to the styrene-butadiene rubber (SBR)/silica composites. The reaction between bis [3-(triethoxysilyl) propyl] tetrasulfide (TESPT) and silica with different basic ILs is investigated. The results show that the ILs with stronger alkalinity exhibit higher catalytic efficiency. The silanization occurs at lower temperature with the incorporation of ILs. The parameters characterizing interfacial interactions show that the interfacial adhesion is gradually improved with increasing alkalinity of ILs. Consequently, the resulting composite with ILs possessing strong alkalinity exhibits excellent whole performance compared with the composites without ILs. Especially, the energy loss of rubber wheel in rolling process is gradually decreased. The composites exhibit excellent abrasion resistance and heat build-up.

The dispersion of filler and interfacial interaction are crucial in determining the properties of rubber composites. Aiming to improve the dispersion and filler–rubber interaction, we introduce rubber graft bearing oniums in a rubber/silica composite. To fulfill this goal, the graft, which is prepared via thio‐ene click reaction between 1‐methylimidazolium mercaptopropionate (MMP) and the pendent vinyl groups of a solution‐polymerized styrene‐butadiene rubber (SSBR), is introduced into the silica‐filled styrene‐butadiene rubber (SBR) composite. The dispersion of silica and interfacial interaction are improved via hydrogen bonding interaction. Moreover, the graft exhibits catalytic effect toward the silanization, which can improve interfacial interaction in the composites with bis [3‐(triethoxysilyl) propyl] tetrasulfide. With 2 phr of the graft, the tensile modulus (stress at 300% strain) is increased by 18% and the abrasion loss is decreased by 31%. This study opens a new attempt to improve the filler dispersion and filler–rubber interaction in the composites with onium‐bearing polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48243.

With increasing concerns in energy saving and environmental protection, the green tire with low rolling resistance, low heat build-up, and high wear resistance have drawn extensive attention in tire industry and academic community. In order to meet the requirements of green tire, the development of high-performance rubber composites with high dynamic properties and outstanding abrasion resistance is critical. However, the balance between the "magic triangle" of tire tread properties (wet resistance, rolling resistance and abrasion resistance) is challengeable due to many influencing factors. In this review paper, we mainly discuss the effects of the dispersion of nanofillers and interface interaction between nanofillers and rubber on the dynamic properties of the rubber composites. Particularly we have discussed the regulation of wet resistance and rolling resistance by using tan δ value at temperature of 0℃ and 60℃ as the measurement indexes. Firstly, the influence of dispersion of nanofillers in the rubber matrix on the properties of rubber composites has been reviewed. According to the current research results, the dispersion of carbon black, silica, layered silicate, etc. could be improved significantly through the methods of surface modification, improvement of the processing and hybridization between two different kinds of filler, and so on. As a result, the improvement of the dispersion of nanofillers in the rubber matrix is achieved. The increased wet traction and lowered rolling resistance could be realized simultaneously. Consequently, the better balance of the wet resistance, rolling resistance and abrasion resistance could be achieved. Secondly, we have discussed the effect of interface interaction between nanofillers and rubber on the properties of tread rubber. It is well know that the compatibility between fillers and rubber is critical to achieve the excellent dynamic properties of rubber composites. And the compatibility between fillers and rubber is affected by the interfacial interaction. With introducing the physical interaction (such as hydrogen bond), or the chemical interaction (such as ionic bond and chemical bond), the interface interaction between fillers and rubber could be strengthened. Accordingly, the dynamic properties, including the increased wet traction and decreased rolling resistance, have been improved. However, the dynamic properties might be deteriorated due to the strong interaction. In conclusion, in order to get the best balance of wet resistance, rolling resistance and abrasion resistance, appropriate dispersion method and rational interfacial design are crucial in developing tread materials. The emerging of new nanoparticles also provides unique opportunity to achieve the better dynamic properties of the tread rubbers. � 2016, Science Press. All right reserved.

The strategy of using hybrid fillers with different geometric shapes and aspect ratios has been established to be an efficient way to achieve high-performance polymer composites. While, in spite of the recently renowned advances in this field, the mechanism of synergistic behavior in the system is still unclear and equivocal. In this study, we systematically investigated the mechanism for the synergistic reinforcement in an elastomer reinforced by nanocarbon hybrids consisting of 2D reduced graphene oxide (rGO) and 1D carbon nanotubes (CNTs). The improved dispersion state of hybrid filler was attested by Raman, UV-Vis spectra and morphological observations. In addition to the phenomenological evidences, we substantiated a stronger confinement effect of hybrid network on chain dynamics, for the first time, with molecular concepts by dielectric relaxation analysis. The formation of a glassy interphase with orders of magnitude slower chain dynamics than that for bulk chains has been explicitly demonstrated in the hybrid system. Besides improved dispersion upon hybridization, it is believed the formation of a glassy interphase is another crucial factor in governing the synergistic reinforcement capability of hybrid composites. We envision this new finding provides significant insight into the mechanism of synergistic behavior in hybrid-filled polymer composites with molecular concepts.

The filler dispersion and network in rubber composites are critical factors in determining the properties of the composites. In this study, we incorporate a graphene-like layered material, molybdenum disulfide (MoS2), to partly substitute carbon black (CB) in styrene butadiene rubber/CB composites, and primarily focus on the filler dispersion and network as well as their effects on the mechanical properties of the composites. With the addition of MoS2, the dispersion of CB is greatly improved and the CB agglomerates are suppressed. When MoS2 substitution content is less than 1 phr, the modulus and strength of the composites are slightly decreased due to the release of trapped rubber from CB agglomerates, while the dynamic properties are significantly improved. At higher MoS2 substitution loading, MoS2 and CB form a denser and continuous hybrid filler network, which shows remarkable synergistic effects in improving the both static and dynamic mechanical properties of the composites. For example, the addition of 3 phr MoS2 leads to a 50% increase in the tensile modulus and 10 °C decrease in the heat build-up of the composite.

The application of polymers as an essential class of material was greatly inhibited due to the aging failure of these versatile materials during normal use. Hence, it is generally recognized that stabilization against thermo-oxidative aging is indispensable to extend the service life of polymers for long-term applications. However, toxicity and pollution of the state-of-the-art antiaging technologies have long been puzzles in the polymer industry. Herein, sustainable carbon nanodots (CDs), synthesized by facile and cost-effective microwave-assisted pyrolysis, are used for first time as radical scavengers to resist the thermo-oxidative aging of elastomers. We have demonstrated that incorporation of the resultant CDs could be green and generic radical scavengers toward highly aging-resistant elastomers. Furthermore, by controlling the photoluminescent quantum yield of the CDs with various passivated agents, tunable radical scavenging activity was achieved. We established for the first time that the aging resistance originates from the prominent reactive radical scavenging activity of the CDs, which was rationally controlled by their photoluminescent quantum yield.

The dispersion of nanofiller in polymer composites is critical in governing the ultimate performances. Present study aimed to improve the dispersion of silica in elastomeric materials based on natural rubber (NR) composites using the nanoplatelets of molybdenum disulfide (MoS2), a graphene-like layered inorganic. NR latex was co-coagulated with MoS2 suspension to form NR/MoS2 compounds (1∼5 phr). Then silica (30 phr) was incorporated into NR/MoS2 compounds, followed by curing with sulfur, to obtained NR/MoS2/silica composites. The dispersion state of silica in the composites was examined by TEM and the effects of MoS2 on the performance of the composites were investigated. It was found that a small amount of MoS2 nanoplatelets significantly improved the silica dispersion. Consequently, the static and dynamic mechanical properties of the crosslinked natural rubber materials were greatly enhanced. The improved dispersion of silica is associated with charge transfer interaction, giving rise to electrostatic repulsion among silica.

The use of silica to partially replace carbon black is a common practice in the fabrication of "green tires." Although some degree of consensus has been approached concerning the improved performance conferred by silica substitution, such as the improved dispersion of carbon black, a quantitative understanding of the relationship between filler networking and the performance of rubber composites has not been established. Thus, an investigation focusing on filler network structure and the correlation between the network structure and the reinforcement of rubber composites was conducted. We prepared solution-polymerized styrene-butadiene rubber (SSBR) reinforced by carbon black and carbon black/silica in different ratios. To exclude as much of the effect from changed crosslinking, and figure out how filler blending influences filler dispersion and filler network structure, the silane generally used in the tire industry was not adopted. The quantitative predictor, the mass fractal dimension d(f), was derived from the Kraus model and the Huber-Vilgis model. We found that when the amount of substituted silica increases, the filler cluster branching decreases, accompanied by increased reinforcement efficiency. The depressed filler networking induced by silica substitution at an appropriate proportion leads to improved dynamic properties, including lower rolling resistance and better wet skid. When the silica proportion in the filler is too high, severe filler networking is observed, resulting in decreased reinforcing efficiency and impaired dynamic properties.

Reduced graphene oxide (RGO) was prepared by the reduction of graphene oxide (GO) with rhodanine. During the reduction, rhodanine was converted into polyrhodanine via oxidative polymerization initiated by GO, and the RGO was subsequently decorated with polyrhodanine. The reduction process and polymerization have been verified. Rhodanine reduced GO with high efficiency. Additionally, rhodanine is polymerized during the GO reduction process. The wrapping of polyrhodanine onto RGO is also verified. Using this novel modification process, the elastomer/graphene composites were prepared by the in situ interfacial modification of elastomer/GO compounds with rhodanine during the processing. Because of the unique reactivity of polyrhodanine during curing, strong interfaces were observed to form in the resulting elastomer/RGO composites. Furthermore, because of the substantially improved interfacial adhesion, combined with the improved dispersion state, the elastomer/RGO composites exhibited significantly improved mechanical properties compared with the elastomer/GO composites. Regarding the facile process and strikingly high modification efficiency, the present work offers new insight into designing high-performance elastomer/graphene composites by combining interfacial chemistry and curing chemistry. This journal is