Devulcanization Techniques for Efficient Tire Recycling

Method for recycling vulcanized rubber to increase performance and allow higher recycled rubber content compared to prior methods. The key is using a barrier material to prevent sulfur and cure accelerators from the fresh rubber diffusing into the recycled rubber during co-vulcanization. This prevents additional crosslinking in the recycled rubber and improves bonding between the two types of rubber. The barrier material forms a diffusion barrier around the ground recycled rubber particles in the fresh rubber matrix during vulcanization.

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Method for producing reclaimed rubber from waste tires using ultrasonic cracking. The method involves crushing tires, mixing with oil and acid, ultrasonic agitation, aging, extrusion, and kneading. The ultrasonic agitation step breaks down the rubber's crosslinked network using ultrasonic waves. The aging step allows the oil and acid to penetrate. The extrusion and kneading steps further process the rubber. The ultrasonic cracking improves reclaimed rubber properties compared to traditional methods.

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A process for preparing high quality rubber powder from waste tires with improved yield and desulfurization compared to existing methods. The process involves cutting waste tires into particles, followed by steps of magnetic separation, microwave radiation, grinding, magnetic separation, microwave radiation, selective separation, desulfurizer treatment, ultrasonic treatment, ammonia circulating fluidized bed treatment, and final microwave radiation to produce the rubber powder. This sequence of treatments allows smooth grinding, high yield, good desulfurization, and high quality rubber powder.

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Waste disposal method for dissolving rubber products like tires and seismic isolation rubber units to recycle the rubber and separate the rubber and metal components. The method involves immersing the waste rubber in a solvent containing fatty acid methyl ester (FAME) to dissolve the rubber at temperatures below the ignition point. Before dissolution, the rubber can be pretreated with a solvent containing propyl bromide to accelerate dissolution without damaging the metal. This allows separating and recycling the rubber without burning or shredding the waste.

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A process for producing tread regenerated rubber that reduces pollution and improves properties compared to conventional methods. The process involves treating waste tire rubber powder with a specific combination of solvents, catalysts, and crosslinking agents to regenerate the rubber into usable tread material. The solvents used are N-methylpyrrolidone (NMP) and dimethylformamide (DMF). The catalyst is dibutyltin dilaurate (DBTDL). The crosslinking agent is N,N'-methylene bisacrylamide (MBA). The mass ratios used are 1:1:1 (solvent:catalyst:crosslinking agent) and 2:0.7:2.5 (rubber:solvent:crosslinking agent). This treatment allows efficient desulfurization and regeneration of the rubber

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A method for producing devulcanized rubber with improved properties after vulcanization. The method involves heating and mixing vulcanized diene rubber with a desulfurizing agent that is a solid amine compound. The mixing is done at temperatures below 100°C to prevent rubber chain scission. Applying a shear force during mixing enhances desulfurization efficiency. The amine compound selectively cleaves sulfur crosslinks without degrading the rubber chain. This produces devulcanized rubber with better post-vulcanization properties compared to conventional devulcanization methods.

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Devulcanized rubber with high molecular weight liquid component for recycling and reuse in rubber products like tires. The devulcanization process involves heating vulcanized rubber in a solvent containing an aldehyde with a carbon chain of at least 2. This breaks crosslinks and generates free radicals. Adding a compound with aliphatic double bonds further helps cleavage. The solvent and reaction conditions prevent complete degradation, yielding a devulcanized rubber with a soluble component having molecular weight 260-600kDa. This can be used as a high molecular weight liquid rubber in new crosslinked products like tires, providing better mechanical strength compared to conventional devulcanized rubbers.

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Continuous process for preparing high-strength liquid rubber from waste tires that can be used as a processing aid in tire manufacturing. The process involves crushing tires, removing impurities, and then blending the pulverized rubber with specific proportions of liquid rubbers, functionalized liquid rubbers, and unsaturated dienoic acids. This modified rubber is then extruded to desulfurize and regenerate it into a high-strength, low-viscosity liquid rubber that has improved compatibility, adhesion, and properties compared to unmodified waste tire rubber.

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Manufacturing devulcanized rubber that can be used as a viable substitute to virgin rubber in different types of applications, such as in tyres and general rubber goods such as conveyor belts, sheeting, extrusion profiles and moulded products. The process includes introducing tyre rubber particles to a mill; introducing a gaseous flow in the mill for generating a field of high turbulence, strong eddies and high energy impact between the tyre rubber particles which causes micronization and rupture of the tyre rubber particles due to extreme hysteresis and mechanical forces sufficient to at least partially devulcanize the tyre rubber particles; and fast dissipation of the heat generated into the gaseous flow.

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Method for devulcanizing vulcanized rubber to recycle old tires and improve properties of rubber articles. The method involves using a twin-screw extruder with a regenerative agent feed point in the upper half of the barrel. The extruder devulcanizes the rubber at temperatures around 100-150°C. This breaks the sulfur bonds without shortening the polymer chains. The devulcanized rubber can be further processed into new rubber mixtures with better properties compared to using fully devulcanized rubber. The extruder configuration with regenerative agent feed allows efficient devulcanization without chain scission.

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Devulcanization of rubber products like tires to recycle them by breaking the sulfur crosslinks without melting the rubber. The process involves mixing the vulcanized rubber particles with a high-boiling swelling agent and heating them in oxygen. The high-boiling swelling agent causes the rubber to swell, making it easier to break the sulfur bonds. The oxygen oxidizes the sulfur and devulcanizes the rubber. After devulcanization, the rubber chains can be separated from the swelling agent. This allows recycling of the devulcanized rubber by reusing it in new products rather than disposing of it.

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A method to recycle old tires into reusable rubber by breaking the crosslinks in the tire rubber and adding functional groups to improve compatibility with other rubber compounds. The method involves using an extruder to mechanically shear and heat the tire rubber powder. This partially breaks the three-dimensional network crosslinks, reverting the rubber to a linear structure. Simultaneously, the high temperature and mechanical force cause chemical reactions between the tire rubber and a composite functionalized modifier containing groups like -C=C- and -COOH. This grafts functional groups onto the reverted rubber to improve its properties and compatibility with other rubbers.

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High-performance reclaimed rubber with improved properties obtained through a modified desulfurization process using specialized molecular sieves. The reclaimed rubber composition includes rubber powder, softening agents, resin, molecular sieves, activator, and pine tar or cottonseed oil. The closed-loop desulfurization process involves sequentially adding the components at controlled temperature and pressure for 120-150 minutes. Y-type molecular sieves like NaY, Sn-CeMoOx/Y, CeO2+Co-Mo/Y, CH3I-AgBF4+Co-Mo/Y, or CeO2+Sn-CeMoOx/Y are used. This modified desulfurization process allows efficient rubber regeneration with reduced desulfurization time, temperature, and chemicals compared to conventional methods. The reclaimed rubber has improved properties like Mooney viscosity and mechanical strength

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Reclaimed rubber made by crushing waste vulcanized rubber and separating it by magnetic separation to obtain rubber powder, which is then dynamically desulfurized and refined. The preparation includes uniformly mixing 98-102 parts by weight of waste tire rubber powder, 4-8 parts by weight of regeneration activator, 6-12 parts by weight of paraffin oil and 1-4 parts by weight of anti-aging agent, Add to the reaction kettle for reaction, the reaction temperature is 100-130 °C, and the reaction time is 2-4 hours; After completion, the cooling water is cooled, and the temperature of the material in the reaction kettle is lowered to 60-80 ° C, and then 6-12 parts of regeneration activator, 0.2-5 parts of aromatic oil, 0.8-2.4 parts of zinc oxide, 0.3-1.2 parts of regenerating activator are added.

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A liquid phase method for recycling waste rubber that involves regenerating the rubber in a solvent instead of using high temperature and solid phase methods. The process involves swelling the rubber powder in an organic solvent and then reacting it with a regeneration activator. The solvent allows full swelling of the rubber particles, exposing the crosslinks for reaction. Ultrasonic stirring helps move the chains. The reaction steps are designed to sequentially break the polysulfide, disulfide, and monosulfide bonds in order. This prevents over-reaction and oxidation. The method provides better quality and yield of recycled rubber with improved properties.

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A system for regenerating vulcanized rubber from waste rubber products to reclaim some of the material for further use. The system uses a sequence of conveyors, stirring, cooling, and de-crosslinking steps to break down the crosslinks and soften the rubber. This allows the recycled rubber to be reused in new products, reducing waste and conserving raw materials. The system avoids high temperatures and energy-intensive processes by using friction stir heating instead of direct heating.

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Waste rubber processing technology that improves the quality of recycled rubber by pretreating the waste rubber powder before desulfurization. The pretreatment involves spraying a suspension of silica nanoparticles onto the waste rubber powder. This forms C-Si bonds on the surface that buffer the desulfurization temperature and prevent excessive chain scission. It allows selective breaking of weaker bonds like SS and CS before the main chain C-C bonds. This avoids over-desulfurization that degrades the mechanical properties.

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A continuous rubber regeneration system for waste tires that uses intelligent decrosslinking to improve the quality and yield of recycled rubber. The system uses a series of integrated modules for preheating, decrosslinking, kneading, cooling, and catalytic combustion. It features separate preheating zones with oil circulation, a twin-screw desulfurization extruder for decrosslinking, and a two-stage cooling system. The modules are connected in sequence to efficiently process and regenerate waste tire rubber into high-quality, odor-free rubber products.

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Devulcanization process for recycling rubber without degrading the properties, using organic acids in nonpolar solvents and mineral oils. The process involves grinding the rubber, adding a mixture of mineral oil and nonpolar solvent like toluene, xylene, or benzene, suspending thioglycolic acid, heating, separating the particles, and washing. This allows efficient devulcanization compared to high-temperature, high-pressure methods. The devulcanized rubber can then be used in applications where vulcanized rubber is required.

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Devulcanizing vulcanized rubber to recycle old tires without shortening the polymer chains. The method involves grinding the tire into small particles, extruding them at low shear rates to maintain chain length, cooling, and further kneading to complete devulcanization. The low shear extrusion prevents chain scission. The final step can involve filtering and heating.

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