Atmospheric oxidation and self-heating in rubber-containing materials

摘要

Among the materials listed by Bowes that are susceptible to self-heating and spontaneous ignition, rubber-containing products are conspicuously absent. Tire-dump fires are a special environmental problem due to the difficulty in fighting them, the large amounts of water needed, and the noxious quality of the aqueous run-off and of the smoke. Many of these fires are maliciously set, but legislation in various jurisdictions concerning the height of perimeter fences and the clear space between the fence and the edge of the dump itself help to reduce their frequency. Nevertheless, tire-dump fires sometimes do not fit the profile of having been set near the perimeter with the help of an accelerant: these are now classified by the Scraptire Council of the (U.S.) Rubber Manufacturers' Association as accidents, although an earlier, now defunct, version of this web page blamed either lightning strikes or "Acts of God." It is the latter class that we attempt to illuminate in this study. In fact, we will show that self-heating caused by atmospheric oxidation can occur in tire rubber, and therefore the possibility of spontaneous ignition cannot be discounted. Moreover, the observation that some such fires collapse in the middle (similarly, in some of our experiments below) only tends to strengthen this conclusion.