While a definition of devulcanization and reclaimed rubber exists in ASTM Designation D1566 15 (Standard Terminology Relating to Rubber) and the former is again repeated in ASTM Designation: D6814 02 (Standard Test Method for Determination of Percent Devulcanization of Crumb Rubber Based on Crosslink Density), no associated material classification standards related to this subject matter currently reside within ASTM. Currently China and India are the two largest producers of reclaimed rubber and both countries have material classification standards related to reclaim rubber. The most common processes yielding these reclaimed rubber materials are of a nature such that these processes are prohibited in both North America and Europe (whereas the importation of these materials or products manufactured form these materials is generally allowed). The process prohibition notwithstanding, the growth of the production and consumption of reclaim rubber in India and China have also benefited greatly from the existence of these material classifications. These material classifications have the benefit of providing potential consumers easily identifiable and discrete material characterizations that aid in consumer choices with respect to these materials. Moreover, the information set related to these materials is made more relevant to consumers, namely rubber compounders, molders or vertically integrated enterprises with both competencies, by generally expressing the nature of these materials in a language understood by these consumers, or more specifically, by outlining specific compound physical properties such as tensile strength, elongation and numerous other properties described in ASTM Designation D1566 15 (Standard Terminology Relating to Rubber) and the testing protocols for which are contained in other ASTM Designations. Author providence, language translations challenges in some instances and language imprecision in other instances as well as classification challenges and shortcomings more generally (the absence of addressing important physical properties like abrasion resistance as an example) are such that the North American and European consumer particularly and other consumers of recycled rubber materials would benefit from a set of better devulcanized rubber classification standards and particularly as ultimately adopted by and published by ASTM. ASTM definitions aside, companies that have developed devulcanization technologies, processes, infrastructure and materials as well as many consumers and potential consumers of materials on offer from these enterprises draw a distinction (albeit very imprecise) between devulcanized rubber and reclaimed rubber. The primary contention of devulcanization enterprises is that sulfur-chain-scission is accomplished without harm to the main carbon backbone whereas reclaimed rubber exhibits varying levels of carbon backbone harm or depolymerization. Devulcanization enterprises would additionally contend that the level of thermal content and utilization of certain chemicals typically found in most rubber reclaiming processes are such that reclaimed rubber tends to exhibit a common and very recognizable odor as well as an oily texture absent from devulcanized rubber. Irrespective of who would concur or not concur with these imprecise delineations, a set of material characterization standards focused largely on common rubber compound physical properties authored and proposed by individuals from within the devulcanization industry, as evaluated by rubber consumers and other rubber experts alike, would greatly assist the health of a devulcanization industry and the adoption of its materials for the benefit of producers, consumers and the environment. These material characterization standards would seek to build on the language, definitions, test methods and commercial enterprise representative expertise within the ASTM eco-system. The grades of material would seek to address materials derived from a wide range of tire inputs (passenger car tires, whole truck tires as well as truck tire buffings and potentially aircraft tires) and devulcanization process efficacy.
The title and scope are in draft form and are under development within this ASTM Committee.