Our overall objective in presenting this review is to call attention to the very complicated nature of the entire disposal problem. The whole field of scrap-tire disposal is full of alternatives, compromises, legislation, and conflicting reports on technological success. We will present a brief historical section explaining why the disposal of scrap-tires is now a problem (challenge) and the events that lead to it. Statistics on the annual volume of scrap-rubber generated and the volume disposed of by major processes will be reviewed. Existing and proposed legislation will be presented, and the probable impact on the rubber industry discussed. We will state what we believe to be the characteristics of an ideal solution. The technical aspects of scrap-tire disposal will not be neglected. The physical, thermal, and chemical values of a scrap-tire will be presented as a basis of defining potential uses for scrap-tires. The existing and proposed uses of scrap-tires as well as processes for disposal are extremely varied. We have decided to discuss processes for scrap-tire disposal under three general categories: physical applications, recovery of fuel value, and chemical processes. Certainly there are processes which overlap these artificial categories. We have concentrated on literature published in the last five years as a means of updating the reader. Private communications are liberally referred to in our review simply because this is the only way some information is available. We have also concentrated on large-volume uses or processes which have the potential for large volume. These uses or processes may be an immediate solution. However, we have also endeavored to record or comment on all ideas for scrap-tire disposal. Finally, we have expressed our opinion as to future trends.
Experimental results are presented which indicate that scrap rubber vulcanizates, typical of today's tires, can be depolymerized to a product which is essentially a carbon black dispersion in oil. The depolymerization is free radical in nature and requires an efficient chain transfer agent to prevent hardening of the vulcanizate and to increase the rate of depolymerization. The product, termed “Depolymerized Scrap Rubber” (DSR), should be useful, particularly as a rubber compounding ingredient and as a fuel oil extender.
Many procedures and processes for the disposal of scrap tires are available. Because of the complexity of the whole disposal problem—e.g., collection logistics, availability and location of markets for products generated from scrap tires, as well as economics—no one procedure or process is believed to be sufficiently outstanding that all scrap tires would be so processed. Several procedures or processes must be used to solve this industry problem. The procedure or process selected for disposing of scrap tires will be dictated primarily by economics and geographic location. Certainly, all procedures must be proven environmentally acceptable.
The smoke inhibitory activity of hydrated fillers in SBR is centered primarily in condensed-phase processes and is analogous to the generally accepted mechanism of flame retardation by the hydrates. Dissipation of heat, which disfavors pyrolysis and favors competing crosslinking reactions is probably involved. These reactions should occur chiefly among polybutadiene segments of the polymers. In addition, the smoke-suppressant efficiency of hydrated fillers should depend upon the crosslinking efficiency of the rubber. Finally, although smoke generation in latex rubber goods presents a challenge, substantial practical reductions in visible smoke can be achieved through the selection of proper hydrated fillers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.