• Elastomers and Composites
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• v.35 no.4
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• pp.288-295
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• 2000

It has been tried to decrease the crosslink density of vulcanized EPDM (ethylone-propylene-diene terpolymer) rubber through a chemical devulcanization treatment. Phase transfer catalyst, alkali metal (i.e., sodium), and triphenylphosphine have been used as a chemical agent ul the devulcanization treatment. Also it has been estimated the effect of the devulcanization treatment in the case of utilization of 2-butanol as a devulcanization reaction solvent. In the devulcanization treatment using quaternary ammonium salt as a phase transfer catalyst. the devulcanization effect has been studied with the variation of catalyst molecular weight and the choice of bromide or chloride cation. In the devulcanization treatment using sodium, it has been estimated the devulcanization treatment effect depending upon the variation of reaction variables such as amount of sodium used, reaction temperature, pressure of hydrogen gas, which is used as a reaction environment. The $M_c$ value (number average molecular weight between two crosslink points) has been experimentally estimated by the equilibrium swelling method and it is quantitatively related to the crosslink density. The estimation of devulcanization effect for vulcanized EPDM rubber has been carried out by the comparison of the $M_c$ values between the untreated and the treated specimens.

• Resources Recycling
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• v.24 no.3
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• pp.59-65
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• 2015

Recycling of vulcanized rubber products is a serious problem in the world. A quantity of generated waste tires becomes much more and more because of increasing demands on automobiles, resulted in the cause of serious secondary pollution by sulfur component that is crosslinked to incineration or landfill. In addition, crosslinked surfur is used to interfere with the binding of the raw material rubber. In this study, we analyzed the degree of devulcanization by the chemical devulcanization. Devulcanization ratio of the samples were systematically analysed by variables such as time and temperature. In addition, the effect of swelling method as a pre-treatment process was also measured. A rubber specimen was deepened in a organic 2-buthanol solutions during various times of 1 ~ 5 hrs at 100, 150, $200^{\circ}C$ respectively, then to calculate the crosslink density and the number average molecular weight by using a parallel expansion process, which showed devulcanization degree of analyzed samples quantitatively. Also, the mechanical properties were measured with the samples prepared by using a hot press.