Independent investigation on the influences of the processing conditions on the reclamation of crosslinked isoprene rubber after the impregnation of a reclaiming reagent

ABSTRACT In this study, the reclamation of sulfur (S)‐cured isoprene rubber (IR) was investigated independently after the impregnation process of the reclaiming reagent diphenyl disulfide (DD) into the crosslinked IR matrix with supercritical carbon dioxide (scCO2) as the transmission medium. According to the mass uptake of DD into IR and scanning electron microscopy–energy‐dispersive X‐ray spectrometry measurements, DD was highly impregnated and homogeneously dispersed in the network under 12 MPa at 80°C for 11 h in scCO2. During the impregnation process, almost no reclaiming reaction occurred. Then, through three different reclaiming methods, a mechanochemical method, a chemical method with oxygen, and a chemical method without oxygen, the influences of the shear force, reclaiming atmosphere, reaction time, and amounts of reclaiming reagent on the reclamation with crosslinked IR with pre‐impregnated DD were independently investigated and compared with those of the reaction without pre‐impregnated DD. The sol fraction of the reclaimed rubber and molecular weight of the sol were measured. The results show that the reclaiming speed greatly depended on the amount of reclaiming reagent and that the reclaiming reaction was dramatically accelerated when the reclaiming reagents were pre‐impregnated into the crosslinked IR under the same processing conditions. This indicated that the impregnation time of the reclaiming reagent into the crosslinked network constituted a large proportion of the reclaiming time. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40298.