Microwave-induced thermal conversion of ethylene-vinyl acetate copolymer/natural rubber composite fom shoe sole scrap

Abstract

Pyrolysis and gasification processes were utilized in order to evaluate the feasibility on production of value added fuels from ethylene-vinyl acetate copolymer/natural rubber composite (EVA/NR) which is in form of shoe sole scrap. The heat for thermal conversion was supplied via novel microwave induced heating using silicon carbide (SiC) as microwave absorber. Similar experiments were also performed using conventional furnace to compare the effect of heating method. The pyrolysis/gasification temperature ranged from 250-1,000°C which could be reached within a few minutes for microwave. The reaction took place in 100%Ar and 99% Ar/1%O2 atmosphere for pyrolysis and gasification, respectively. The influence of microwave power, reacting atmosphere and amount of SiC on the characteristic of products was evaluated. Favorable conditions for producing high gas fraction with greater proportion of energy rich hydrocarbon and hydrogen were determined. From the results, it was shown that thermal conversion under atmosphere that has oxygen can be generating higher content of H2, CO2, and light hydrocarbon than in 100% Ar atmosphere. More gas fraction was obtained from microwave heating than that of conventional furnace while solid product from the later technique was higher. Gas product from microwave heating increase with higher microwave power and contained mainly H2, CO2, and light hydrocarbon. The effect of silicon carbide ratio is not clearly because of limitation of microwave heating in this experiment. Compared with convention heating, microwave induced heating required significantly shorter times which resulted in superior overall efficiency of the process, suitable for thermochemical conversion of this polymerics waste to more valuable fuels.