Effect of Temperature on Devulcanization of Waste Sidewall Rubber by Supercritical Ethanol

Li, Xiang; Deng, Xiujuan; Dong, Chao

doi:10.21577/0103-5053.20180093

Cited by 7 publications

(8 citation statements)

References 35 publications

(43 reference statements)

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“…Not only solvents, such as alcohol and ketone, were used during GTR regeneration processes, but supercritical solvents (water, ethanol, carbon dioxide and toluene) were also studied. Li et al [110] investigated the effect of temperature on the regeneration of waste sidewall rubber from passenger car tires using supercritical ethanol and diphenyl disulfide (DPDS) as a regeneration agent. As shown in Figure 18, increasing the reaction temperature from 240 to 270 • C increased the RTR sol fraction from 25 to 55% since ethanol reached its supercritical state making it easier to penetrate into the GTR vulcanized structure to facilitate the crosslinked network breakdown.…”

Section: Thermo-chemical Processesmentioning

confidence: 99%

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Recycling Waste Tires into Ground Tire Rubber (GTR)/Rubber Compounds: A Review

2020

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Recycling and recovery of waste tires is a serious environmental problem since vulcanized rubbers require several years to degrade naturally and remain for long periods of time in the environment. This is associated to a complex three dimensional (3D) crosslinked structure and the presence of a high number of different additives inside a tire formulation. Most end-of-life tires are discarded as waste in landfills taking space or incinerated for energy recovery, especially for highly degraded rubber wastes. All these options are no longer acceptable for the environment and circular economy. However, a great deal of progress has been made on the sustainability of waste tires via recycling as this material has high potential being a source of valuable raw materials. Extensive researches were performed on using these end-of-life tires as fillers in civil engineering applications (concrete and asphalt), as well as blending with polymeric matrices (thermoplastics, thermosets or virgin rubber). Several grinding technologies, such as ambient, wet or cryogenic processes, are widely used for downsizing waste tires and converting them into ground tire rubber (GTR) with a larger specific surface area. Here, a focus is made on the use of GTR as a partial replacement in virgin rubber compounds. The paper also presents a review of the possible physical and chemical surface treatments to improve the GTR adhesion and interaction with different matrices, including rubber regeneration processes such as thermomechanical, microwave, ultrasonic and thermochemical producing regenerated tire rubber (RTR). This review also includes a detailed discussion on the effect of GTR/RTR particle size, concentration and crosslinking level on the curing, rheological, mechanical, aging, thermal, dynamic mechanical and swelling properties of rubber compounds. Finally, a conclusion on the current situation is provided with openings for future works.

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Section: Thermo-chemical Processesmentioning

confidence: 99%

“…Effect of temperature on the sol fraction of regenerated sidewall rubber obtained from a passenger car tire (regeneration reaction conditions are 8 MPa for 60 min) (reproduced with permission from[110]). …”

mentioning

confidence: 99%

Recycling Waste Tires into Ground Tire Rubber (GTR)/Rubber Compounds: A Review

2020

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“…Sufficient experiments analyzed the efficiency of the devulcanization process by investigating the DoD and mechanical properties of composite materials. Methods like gel permeation chromatography (GPC), NMR, infrared (IR) spectroscopy, differential scanning calorimetry (DSC), or thermogravimetric analysis (TGA), in addition to Horikx plots, are commonly used to identify structural changes, compositions, or characteristics of the material after recycling 32,35–38 . The flowability and revulcanization ability are essential characteristics of reclaimed rubber.…”

Section: Introductionmentioning

confidence: 99%

“…Methods like gel permeation chromatography (GPC), NMR, infrared (IR) spectroscopy, differential scanning calorimetry (DSC), or thermogravimetric analysis (TGA), in addition to Horikx plots, are commonly used to identify structural changes, compositions, or characteristics of the material after recycling. 32,[35][36][37][38] The flowability and revulcanization ability are essential characteristics of reclaimed rubber. The first is important to produce a new product, and the second is a key step to obtaining a useful product.…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical devulcanization ofEPDMrubber waste. Correlation of process parameters with sol–gel analyses and revulcanization properties

Gschwind

Jordan

Vennemann

et al. 2023

J of Applied Polymer Sci

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Ethylene-propylene-diene rubber (EPDM) scrap was devulcanized in an internal mixer with varying amounts of dibenzamido diphenyl disulfide (DBD) at temperatures below 200 C. The devulcanization effect and sol-gel analyses of the devulcanizates, and the mechanical properties of the sulfur-cured revulcanizates were studied. Residual DBD was still present in the sol at 160 C and degraded DBD at 200 C. DBD affects the curing leading to poor properties. So, the temperature must be adjusted according to the DBD concentration to obtain a superior recyclate for sealing systems. At 0.4 wt% DBD, the degradation reaction was already complete at 120 C, but only 52% and 61% of the tensile strength σ and strain at break ε of the virgin material were achieved. At 160 C and 2 wt%, the degradation reaction was complete, and the DBD effect on properties was small; 65% and 86% of σ and ε were recovered, respectively. To prevent property degradation, 200 C was required at 3.9 wt% DBD, resulting in 97% and 95% of σ and ε, but only 70% of hardness.

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“…Supercritical fluids are generally defined as substances at a temperature and pressure above their critical point, and several of these have been used in a variety of industrially important processes (Kazarian, 2000; Park et al, 2001). For instance, Shirai et al (2015) have used supercritical water for the production of fuel gases from a component of woody biomass; Chen et al (1995) have performed depolymerization for oil and chemical recovery using different supercritical fluids; whilst Li et al (2018) performed devulcanization of waste sidewall rubber by supercritical ethanol. Amongst all supercritical fluid, CO 2 is the most common and preferred fluid, particularly for the devulcanization of rubber vulcanizates, because it is an excellent solvent for rubber materials, inexpensive and has a relatively practical and user-friendly critical point (~31.1°C and ~7.38 MPa; Chen et al, 1995; Kazarian, 2000; Khaw et al, 2017; Kojima et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Organic chemical devulcanization of rubber vulcanizates in supercritical carbon dioxide and associated less eco-unfriendly approaches: A review

et al. 2021

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There is a growing need to recover raw materials from waste due to increasing environmental concerns and the widely adopted transition to circular economy. For waste tyres, it is necessary to continuously develop methods and processes that can devulcanize rubber vulcanizates into rubber products with qualities and properties that can closely match those of the virgin rubber. Currently, the most common, due to its efficiency and perceived eco-friendliness in recovering raw rubber from waste rubbers, such as tyres, is devulcanization in supercritical carbon dioxide (scCO2) using commercial and typical devulcanizing agents. The scCO2 has been generally accepted as an attractive alternative to the traditional liquid-based devulcanization media because of the resultant devulcanized rubber has relatively better quality than other processes. For instance, when scCO2 is employed to recover rubber from waste tyres (e.g. truck tyres) and the recovered rubber is blended with virgin natural rubber (NR) in various compositions, the curing and mechanical properties of the blends closely match those of virgin NR. The atmospheric toxicity and cost of the commonly used devulcanization materials like chemical agents, oils and solvents have enabled a shift towards utilization of greener (mainly organic) and readily available devulcanization chemical components. This literature review paper discusses the approaches, which have less negative impact on the environment, in chemical devulcanization of rubber vulcanizates. A special focus has been on thermo-chemical devulcanization of waste tyres in scCO2 using common organic devulcanizing agents.

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Effect of Temperature on Devulcanization of Waste Sidewall Rubber by Supercritical Ethanol

Cited by 7 publications

References 35 publications

Recycling Waste Tires into Ground Tire Rubber (GTR)/Rubber Compounds: A Review

Recycling Waste Tires into Ground Tire Rubber (GTR)/Rubber Compounds: A Review

Mechanochemical devulcanization ofEPDMrubber waste. Correlation of process parameters with sol–gel analyses and revulcanization properties

Organic chemical devulcanization of rubber vulcanizates in supercritical carbon dioxide and associated less eco-unfriendly approaches: A review

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