Methods of Devulcanization

Abstract

Abstract The literature contains the record of numerous methods which have been used to reverse the vulcanization process. Indeed, many of these methods have long been used, especially for purposes of analysis and/or studying mechanisms of vulcanization, so that they are commonplace in most large laboratories. The purpose of this paper is to review the literature on an eclectic basis. The opportunity exists to take a fresh look at some of these techniques with a view to consider up-scaling for recovery of rubber and other ingredients for eventual commercialization. The processes would have to be studied from the standpoint of fine-tuning reactants, solvating media, conditions of minimal degradation, keeping toxic exposure to safe levels, economics, etc. The possibility also exists of combining some of these techniques with others, such as those presented at a recent symposium, which have been developed to a more advanced stage of engineering. Included in a list of the chemical probes which will be discussed and/or referenced are propanethiol, hexanethiol, sodium di-n-butyl phosphite, triphenylphosphine, lithium aluminum hydride, methyl iodide and phenyl lithium. Related methods which have been mentioned include microbial action, grafting reactions, catalysis, microwaves, sonics and solution by o-dichlorobenzene.