A review on devulcanization of waste tire rubber

Abstract

Rubber has become an indispensable material for the technological development of civilization, including simple balloon and complex rocket propellant. Rubber Industry worldwide is using on an average 50% of raw materials. These materials were mostly petroleum-based, except natural rubber (NR), steel cord and bead wire. Using of these petroleum-based raw materials not only depletes natural resources, but also produces more extreme environmental hazards. The waste tire rubber problem is of great magnitude and has far reaching environmental and economic implications. There are some ways for recycling of rubber, such as reclaiming technology, surface treatment, grinding and pulverization technology, devulcanization technology. Methods of devulcanizing rubber (or elastomers) have been researched almost since the time of the discovery of the rubber/sulfur vulcanization process. By devulcanization process the cross-links in the structure of rubber are broken and devulcanized rubber can be revulcanized into a raw material for rubber industry, which is a highly valued form of waste rubber. This study provides a review of the recent advances in understanding of methods of recycling rubber and claims that the capacity of thermomechanical and mechanochemical devulcanization methods of recycling waste tire rubber can be improved in future studies.

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

“…As reported earlier, increasing the filler content with higher crosslink density restricts the chain mobility so higher load is required for elongation increasing the modulus of the blends. Increasing the proportion of rubber powders also increases the presence of carbon black as an effective reinforcing filler restricting the mobility of the rubber chains under tension; i.e., higher modulus [74]. The incorporation of rubber powders into virgin rubber affects the homogeneity of the rubber compounds, which can be corroborated from SEM micrographs.…”

“…On the other hand, reactive compatibilization methods are associated to reactive molecules added during mixing to form a chemically linked interphase, while non-reactive methods are based on the introduction of copolymers (block or graft) and/or nanoparticles (NP) to improve the blend compatibility [14,20,23,73]. It should be mentioned that rubber regeneration also leads to some compatibilizing effect due to possible molecular entanglement with thermoplastic resins and curable rubbers [74].…”

“…GTR regeneration processes are classified as physical and chemical processes in which thermo-mechanical [93], microwave-assisted [21,94], ultrasonic-based [65,95,96], and thermochemical processes [97] are broadly studied. A detailed description of these methods is reviewed in numerous papers and patent applications [28,74,90,92]. In general, physical regeneration uses external energy sources to breakdown the vulcanized structure, while chemical regeneration is based on organic and inorganic reclaiming agents to react with the crosslinked rubber.…”

Recycling NR/SBR waste using probe sonication as a new devulcanizing method; study on influencing parameters

“…The tire waste, due to their huge content and negative effects on ecosystems, have become a major environmental problem. On this basis, recycling of waste tire rubber has been essential from environmental and economical points of view 7,8 Some methods were used for elimination of waste tire rubbers that include burning as a heat source, 9 landlling, 10,11 reclaiming 12-14 etc. It has been known that burning and land-lling of tire rubbers impact environment by releasing greenhouse gases (i.e.…”

Guidelines for Development of Area-Based Plantation of Rubber Commodity in Musi Rawas

“…In terms of regional development, rubber has a big role in driving economic growth in production areas (Azahar et al 2016) either those around the rubber plantations or those in environmental conservation (Warren-Thomas, Dolman, and Edwards 2015) as well as biological resources (Ekadinata and Vincent 2011). The milky fluid exuded from the rubber trunk plant is known as latex (Raulf 2014) can be used as a material for making tires (Akca, Gursel, and Sen 2018), gloves and so on. Indonesia still exports rubber products in the form of raw materials (Virginia and Novianti 2020) or semi-finished products.…”