Development of a new tyre tread by using silanized pre-treated silica nanofiller

The tyre tread compound for passenger car tyres is a blend of natural rubber (NR), styrene butadiene rubber (SBR), polybutadiene rubber (BR) and synthetic polyisoprene (IR). It is designed to have high abrasion resistance and traction, low rolling resistance and long durability in service. To achieve these requirements, reinforcing fillers such as colloidal carbon blacks and synthetic silicas are added to raw rubbers. Reinforcing fillers helps to increase the properties mentioned above and also hardness, tensile properties and tear strength. In recent years, silica has been replacing carbon black in industrial rubber articles, for example passenger car tyres, offering significant benefits. Some studies have shown that using silicas in rubber compounds can reduce the excessive use of the curing chemicals without compromising the mechanical properties of rubber vulcanisates, which are essential for long service life. In this study, effects of 60 parts per hundred rubber by weight (phr) precipitated amorphous white silica nanofiller on the viscosity, curing, mechanical and dynamic properties of NR, SBR, BR and IR rubber compounds were investigated. [Continues.

A review of the reclaiming of rubber waste and recent work on the recycling of ethylene-propylene-diene rubber waste

Rubbers do not decompose easily and therefore disposal of rubber waste is a serious environmental concern. Raw material costs, diminishing natural resources, and the growing awareness of environmental issues and sustainability have made rubber recycling a major area of concern. Reclaiming and recycling rubber waste is a major scientific and technological challenge facing rubber scientists today. This paper reviews a number of important areas related to the reclaiming, characterizing, testing and recycling of rubber waste. These include: chemical and microbial devulcanization with particular emphasis on main chain scission and kinetics of chemical devulcanization reactions; the cutting-edge techniques for reclaiming devulcanized rubber waste by the action of large shearing forces, heat and chemical agents: and analytical techniques and methods for characterizing composition and testing of devulcanized rubber waste, respectively. In addition, some aspects of the recycling of devulcanized ethylene-propylene-diene rubber (EPDM) waste will be reported. EPDM is used extensively in automotive components world-wide and recycling the rubber at the end of its useful service life is of major importance to manufacturers of automotive components

Effect of various efficient vulcanization cure systems on the compression set of a nitrile rubber filled with different fillers

Effect of various efficient vulcanization (EV) sulfur cure systems on the compression set of a nitrile rubber filled with carbon black and silica/silane fillers was examined. The cure systems had different amounts of thiuram and sulfenamide accelerators and elemental sulfur, whilst the loading of zinc oxide and stearic acid activators was kept constant. The fillers had surface areas from 35 to 175 m 2 /g. In this study, the lowest compression set was measured for the rubber filled with carbon black with 78 m 2 /g surface area, which was cured with an EV cure system made of a small amount of elemental sulfur and large amounts of the two accelerators. Interestingly, a small change in the amount of elemental sulfur had a bigger effect on the compression set than did large changes in the loading of the accelerators in the cure system. Among the fillers, carbon black caused less compression set of the rubber vulcanizate than the silica/silane system did

Devulcanization and recycling of waste automotive EPDM rubber powder by using shearing action and chemical additive

In automotive applications, ethylene-propylene-diene rubber (EPDM) is used to manufacture various components and therefore recycling scrap rubber is a major issue. The primary aim of this study was to develop a new method for devulcanizing waste automotive EPDM rubber powder by using shearing action and chemical additive and recycle the devulcanized powder. A semi-industrial twin screw extruder with a shearing action and reactor along with 2-mercaptobenzothiazole-disulfide (MBTS) chemical were used to devulcanize the waste powder at two different feed screw speeds and main rotor speeds at a constant temperature of 220°C. To recycle the devulcanized powder, different amounts of the devulcanized powder were mixed with a commercial EPDM-based automotive rubber strips compound to produce blends. The blends, commercial compound and devulcanized powder were cured with a semi-efficient (SEV) vulcanization system and their viscosity, cure and mechanical properties measured. For the blends, the Mooney viscosity was unchanged with 40 wt%, crosslink density with 20 wt%, tensile strength and elongation at break with 10 wt%, and compression set with 20 wt% of the devulcanized powder. Interestingly, the hardness benefitted from 50 wt% of the devulcanized powder in the blends. The scorch and optimum cure times shortened and the cure rate index rose when the loading of the devulcanized powder in the blends was raised. This new method offered a major new route for devulcanizing and recycling the waste powder

Two advanced styrene-butadiene/polybutadiene rubber blends filled with a silanized silica nanofiller for potential use in passenger car tire tread compound

This is the peer reviewed version of the following article: Journal of Applied Polymer Science, which has been published in final form at http://dx.doi.org/10.1002/app.34221. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Styrene-butadiene rubber (SBR) and poly- butadiene rubber (BR) were mixed together (75:25 by mass) to produce two SBR/BR blends. The blends were re- inforced with a precipitated amorphous white silica nano- filler the surfaces of which were pretreated with bis(3- triethoxysilylpropyl)-tetrasulfide (TESPT). TESPT is a sul- fur-bearing bifunctional organosilane that chemically bonds silica to rubber. The rubbers were primarily cured by using sulfur in TESPT and the cure was optimized by adding non-sulfur donor and sulfur donor accelerators and zinc oxide. The hardness, Young’s modulus, modulus at different strain amplitudes, tensile strength, elongation at break, stored energy density at break, tear strength, cyclic fatigue life, heat build-up, abrasion resistance, glass transition temperature, bound rubber and tan d of the cured blends were measured. The blend which was cured with the non-sulfur donor accelerator and zinc oxide had superior tensile strength, elongation at break, stored energy density at break and modulus at different strain amplitudes. It also possessed a lower heat build-up, a higher abrasion resistance and a higher tan d at low tem- peratures to obtain high-skid resistance and ice and wet- grip. Optimizing the chemical bonding between the rubber and filler reduced the amount of the chemical curatives by approximately 58% by weight for passenger car tire tread. This helped to improve health and safety at work and reduce damage to the environment

Using a sulfur-bearing silane to improve rubber formulations for potential use in industrial rubber articles

The availability of the coupling agent bis (3-triethoxysilylpropyl)-tetrasulfide (TESPT) has provided an opportunity for enhancing the reinforcing capabilities of precipitated amorphous white silica in rubber. Styrene-butadiene rubber, synthetic polyisoprene rubber (IR), acrylonitrile-butadiene rubber, and natural rubber (NR) containing the same loading of a precipitated silica filler were prepared. The silica surface was pretreated with TESPT, which is a sulfur-bearing bifunctional organosilane to chemically bond silica to the rubber. The rubber compounds were subsequently cured by reacting the tetrasulfane groups of TESPT with double bonds in the rubber chains and the cure was optimized by adding sulfenamide accelerator and zinc oxide. The IR and NR needed more accelerators for curing. Surprisingly, there was no obvious correlation between the internal double bond content and the accelerator requirement for the optimum cure of the rubbers. Using the TESPT pretreated silanized silica was a very efficient method for cross-linking and reinforcing the rubbers. It reduced the use of the chemical curatives significantly while maintaining excellent mechanical properties of the cured rubbers. Moreover, it improved health and safety at work-place, reduced cost, and minimized damage to the environment because less chemical curatives were used. Therefore, TESPT was classified as "green silane" for use in rubber formulations

Effect of various efficient vulcanization cure systems on the compression set of a nitrile rubber filled with different fillers

This is the peer reviewed version of the following article: OSTAD-MOVAHED, S., ANSARIFAR, A. and MIRZAIE, F., 2015. Effect of various efficient vulcanization cure systems on the compression set of a nitrile rubber filled with different fillers. Journal of Applied Polymer Science, 132 (8), DOI: 10.1002/APP.41512, which has been published in final form at: https://doi.org/10.1002/app.41512. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Effect of various efficient vulcanization (EV) sulfur cure systems on the compression set of a nitrile rubber filled with carbon black and silica/silane fillers was examined. The cure systems had different amounts of thiuram and sulfenamide accelerators and elemental sulfur, whilst the loading of zinc oxide and stearic acid activators was kept constant. The fillers had surface areas from 35 to 175 m 2 /g. In this study, the lowest compression set was measured for the rubber filled with carbon black with 78 m 2 /g surface area, which was cured with an EV cure system made of a small amount of elemental sulfur and large amounts of the two accelerators. Interestingly, a small change in the amount of elemental sulfur had a bigger effect on the compression set than did large changes in the loading of the accelerators in the cure system. Among the fillers, carbon black caused less compression set of the rubber vulcanizate than the silica/silane system did

Using a sulfur-bearing silane to improve rubber formulations for potential use in industrial rubber articles

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Adhesion Science and Technology on 13/08/2012, available online: http://dx.doi.org/10.1080/01694243.The availability of the coupling agent bis (3-triethoxysilylpropyl)-tetrasulfide (TESPT) has provided an opportunity for enhancing the reinforcing capabilities of precipitated amorphous white silica in rubber. Styrene-butadiene rubber, synthetic polyisoprene rubber (IR), acrylonitrile-butadiene rubber, and natural rubber (NR) containing the same loading of a precipitated silica filler were prepared. The silica surface was pretreated with TESPT, which is a sulfur-bearing bifunctional organosilane to chemically bond silica to the rubber. The rubber compounds were subsequently cured by reacting the tetrasulfane groups of TESPT with double bonds in the rubber chains and the cure was optimized by adding sulfenamide accelerator and zinc oxide. The IR and NR needed more accelerators for curing. Surprisingly, there was no obvious correlation between the internal double bond content and the accelerator requirement for the optimum cure of the rubbers. Using the TESPT pretreated silanized silica was a very efficient method for cross-linking and reinforcing the rubbers. It reduced the use of the chemical curatives significantly while maintaining excellent mechanical properties of the cured rubbers. Moreover, it improved health and safety at work-place, reduced cost, and minimized damage to the environment because less chemical curatives were used. Therefore, TESPT was classified as "green silane" for use in rubber formulations