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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]

The article studies the cure characteristics and mechanical properties of the virgin natural rubber/reclaim ground rubber tire (GRT) blend. According to the authors, the optimum cure time decreases but scorch time remain unaltered with increasing reclaim rubber content in the blend. The authors also reveal that reclaiming of GRT was carried out by tetra methyl thiuram disulfide in the presence of spindle oil at around ambient temperature.

Abstract: The present paper describes the mechanical reclaiming of ground rubber tire (GRT) by tetra methyl thiuram disulfide (TMTD), a multi-functional reclaiming agent. The versatility of the proposed agent is that it acts as a reclaiming agent during reclaiming and as a curing agent during revulcanization of the reclaimed sample. Reclaiming of GRT was carried out on an open two roll mixing mill at various time intervals and different concentrations of the reclaiming agent (TMTD). The degree of reclaiming was evaluated by measurement of the gel content, inherent viscosity of sol rubber, Mooney viscosity of the reclaimed rubber, crosslink density, swelling ratio and molecular weight between two crosslink bonds as a function of milling time. Also, the influence of the gel content on crosslink density at various time intervals on the open two roll mixing mill was determined. A unique correlation between gel fraction and crosslink density obtained at various time intervals and concentrations of reclaiming agent indicated that an optimization of the concentration of TMTD and milling time has a positive influence on improving the efficiency of reclaiming. The reclaiming conditions have been optimized in view of the mechanical properties of the revulcanized GRT and the aging resistance properties of the revulcanized reclaim. The influence of the concentration of sulfur on the mechanical properties in the revulcanized reclaim was also studied. Scanning electron microscopy (SEM) studies further indicate the coherency and homogeneity in the revulcanized reclaim rubber when reclamation is carried out by optimum concentration of TMTD after maximum time of reclaiming. [Copyright &y& Elsevier]

This work is about simultaneous devulcanization and chemical functionalisation of waste styrene butadiene rubber vulcanizate (SBR) using thermo-mechanical treatment and sulphide based multifunctional devulcanizing agent. The as-grown compounds are reinforced with nano-silica and re-vulcanized to prepare rubber composites. The curing and processing characteristics, and mechanical performance are further compared with those of conventional silica based green tire formulations. The extent and quality of devulcanized rubber are monitored through the measurement of sol content, inherent viscosity of sol fraction, cross-link density and degree of devulcanization as a function of cross-link density. By our method based on restoring the curing and other processing parameters, the revulcanized composites offer ∼11 MPa tensile strength, ∼26 MPa tear strength together with elongation at break value as much as 450 %. Such values are comparable with those of the composites consisting of the associated fresh components of the systems. Surprisingly, the higher storage modulus and lower tan ⁡ δ of SBR-devulcanized SBR-silica composite as compared with standard counterpart sample (SBR-silica composite) confirms magnificent dynamic mechanical performance of the composites. This work may pave a new route for reuse of waste tyre in tyre production. [ABSTRACT FROM AUTHOR]