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Development of high efficiency waste tire rubber recycling technology

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Around the world it was estimated that about 30 million tons of tyre waste were generated per year, and 120 thousand tons of them were generated in Taiwan. In 1989, the Environmental Protection Agency (EPA) promoted the recycling of scrapped tires, taking back over 100,000 tons of waste tires. Of these, following crushing, 60 percent of the waste tires were provided to four enterprises, including Yuen Foong Yu Group and Taiwan Cogeneration Corp., as supplementary fuel. However, as burned tires produce five times the amount of sulfur oxides than bituminous coal, manufacturers have greatly reduced their use in recent years due to air pollution concerns. This has resulted in an oversupply of discarded tires in Taiwan. The goal of this project is to develop a continuous process for waste tire rubber devulcanization in an extruder. This process contains two kinds of recycling procedures. In the first procedure, waste tire rubber was mechanically broken down to lower molecular weight by high shearing forces generated from screw rotation in a twin-screw extruder. The mechanism of this reclaiming procedure is the selective scission of cross-links between weak S-S bonds by mechanical shear stress. Additionally, molecular simulation, computational fluid dynamics simulation (CFD), and twin-screw design software were used to accelerate and optimize every details in the developing continuous de-vulcanization process. The checkpoints of the reclaimed waste tyre rubber were exhibited by the accredited standard methods, as followings: (1)Sol component content is 39.2 %;(2) Mooney Viscosity ML (1+4)100°C is 37.6;(3)Tensile strength is 129 Kg/cm2, and (4)Elongation at break is 400.5 % which attain to the project objective. The reclaimed waste tyre rubber were formulated with virgin rubber (30/70 wt% ratio) and re-cured successfully. The checkpoints of the cured blends were exhibited by the accredited standard methods, as followings: (1)Hardness (Shore A) is 61;(2)Ultimate Tensile Strength is 15.3 MPa;(3)Tear strength is 26.1 KN/m, and (5)Elongation at break is 508 % which attain to the project objective.
Keyword
waste tire, extruder, reclaimed rubber
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