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More or less universally, bis(3-triethoxysilyl propyl) tetrasulfide (TESPT) has been used as a coupling agent during dispersion of silica filler in a virgin nonpolar rubber compound. It is for the first time that TESPT has been used as a devulcanizing agent and as-grown devulcanized rubber facilitates the silica dispersion in nonpolar rubber compound without any coupling agent. Dual functionalities of TESPT have been modeled and validated in this work. Various factors like the role of sol-gel content, inherent viscosity of sol rubber, crosslink density, and degree of devulcanization were investigated as a function of devulcanization time and amount of TESPT to optimize devulcanization time and TESPT amount. To study the silica reinforcement, revulcanization of devulcanized SBR was carried out with silica filler and the curing characteristics of the material were evaluated. From the mechanical properties and thermogravimetry analysis the optimum time for devulcanization is determined. Further, scanning electron microscopy (SEM) studies were undertaken to check the coherency and homogeneity of the material., INTRODUCTION Generally, the demand of styrene butadiene rubber (SBR) in tyre industries increases manifold primarily for less C[O.sub.2] emission since SBR offers low rolling resistance and hence accounts for low [...]

This article illustrates the reclaiming of guayule natural rubber (GNR) vulcanizate by bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT), and as-grown reclaim rubber facilitates the silica dispersion in GNR product application without adding any coupling agent. This article deals with the performance evaluation of silica-filled revulcanizates with promising application in green tire. The extent of reclaiming was monitored through the measurement of sol content, cross-link density, Mooney viscosity, and degree of reclaiming. The differential scanning calorimetry study was carried out to evaluate the fraction of immobilized polymer chains and its dependence on cross-link density of the vulcanizates. The Fourier transform infrared study and also sulfur analysis independently indicate the attachment of the fragmented TESPT with the polymer chain and cross-link bonds. The study of mechanical properties clearly shows that in revulcanized GNR, the optimum property is achieved when reclaiming time is set for 40 min. The effect of reclaiming time on dynamic mechanical behavior such as storage modulus and loss tangent was studied. The scanning electron microscopy studies show the coherency and homogeneity of silica-filled revulcanize rubber with reclaiming time. [ABSTRACT FROM AUTHOR]

Ethoxy functionalized devulcanize natural rubber (DeVulcNR) is used as compatibilizer for silica/graphene oxide (SiO2@GO) hybrid fillers in the styrene butadiene rubber (SBR) to fabricate SBR composites. The dispersion behavior of SiO2@GO hybrid filler was investigated through scanning electron microscopy (SEM) analysis of the tensile fracture surface along with the broken rubber surface developed by plunging into liquid nitrogen. The rubber–filler interfacial interactions were evaluated through the measurement of equilibrium swelling experiment, fraction of immobilized polymer chain by DSC study, FTIR analysis, and molecular dynamics simulation. The results reveal that in the presence of DeVulcNR, the rubber–filler interaction is enhanced compared with that of the control formulations containing only SBR. SiO2@GO hybrid‐filler shows synergistic effect on the mechanical properties of the composites in the presence of DeVulcNR. The improved mechanical properties of the SiO2@GO hybrid filler rubber composites may be due to chemical interaction among the functional groups of SiO2 and GO with the DeVulcNR. Further, XRD study indicates that there is no significant layer‐by‐layer restack of GO in the SBR/DeVulcNR composites. The higher storage modulus and lower tan δ of the SiO2@GO hybrid filler rubber composites show superior interfacial interaction between rubber and filler compared with that of the control formulations. POLYM. COMPOS., 40:E1559–E1572, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]