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quote:Originally posted by Ians DaddyI use alot of rubber bands with my job
quote:Originally posted by neilepI like to test their elasticity by firing them at my staff.......which is nice.'Men are the same as women...just inside out !'
The rubber industry has been researching the devulcanization of rubber for many years. The main difficulty in recycling rubber has been devulcanizing the rubber without compromising its desirable properties. The process of devulcanization involves treating rubber in granular form with heat and/or softening agents in order to restore its elastic qualities, in order to enable the rubber to be reused. Several experimental processes have achieved varying degrees of success in the laboratory, but have been less successful when scaled up to commercial production levels. Also, different processes result in different levels of devulcanization: for example, the use of a very fine granulate and a process that produces surface devulcanization will yield a product with some of the desired qualities of unrecycled rubber.The rubber recycling process begins with the collection and shredding of discarded tires. This reduces the rubber to a granular material, and all the steel and reinforcing fibers are removed. After a secondary grinding, the resulting rubber powder is ready for product remanufacture. However, the manufacturing applications that can utilize this inert material are restricted to those which do not require its vulcanization.In the rubber recycling process, devulcanization begins with the delinking of the sulfur molecules from the rubber molecules, thereby facilitating the formation of new cross-linkages. Two main rubber recycling processes have been developed: the modified oil process and the water-oil process. With each of these processes, oil and a reclaiming agent are added to the reclaimed rubber powder, which is subjected to high temperature and pressure for a long period (5-12 hours) in special equipment and also requires extensive mechanical post-processing. The reclaimed rubber from these processes has altered properties and is unsuitable for use in many products, including tires. Typically, these various devulcanization processes have failed to result in significant devulcanization, have failed to achieve consistent quality, or have been prohibitively expensive.In the mid-1990s, researchers at the Guangzhou Research Institute for the Utilization of Reusable Resources in China patented a method for the reclamation and devulcanizing of recycled rubber. Their technology, known as the AMR Process, is claimed to produce a new polymer with consistent properties that are close to those of natural and synthetic rubber, and at a significantly lower potential cost.The AMR Process exploits the molecular characteristics of vulcanized rubber powder in conjunction with the use of an activator, a modifier and an accelerator reacting homogeneously with particles of rubber. The chemical reaction that occurs in the mixing process facilitates the delinking of the sulfur molecules, thereby enabling the characteristics of either natural or synthetic rubber to be recreated. A mixture of chemical additives is added to the recycled rubber powder in a mixer for approximately five minutes, after which the powder passes through a cooling process and is then ready for packaging. The proponents of the process also claim that the process releases no toxins, by-products or contaminants. The reactivated rubber may then be compounded and processed to meet specific requirements.Currently, Landstar Rubber, which holds the North American license for the AMR Process, has built a rubber reprocessing plant and research/quality control lab in Columbus, Ohio. The plant performs production runs on a demonstration basis or at small commercial levels. The recycled rubber from the Ohio plant is currently being tested by an independent lab to establish its physical and chemical properties.Whether or not the AMR Process succeeds, the market for new raw rubber or equivalent remains enormous, with North America alone using over 10 billion pounds (circa 4.5 million tons) every year. The auto industry consumes approximately 79% of new rubber and 57% of synthetic rubber. To date, recycled rubber has not been used as a replacement for new or synthetic rubber in significant quantities, largely because the desired properties have not been achieved. Used tires are the most visible of the waste products made from rubber; it is estimated that North America alone generates approximately 300 million waste tires annually, with over half being added to stockpiles that are already huge. It is estimated that less than 10% of waste rubber is reused in any kind of new product. Furthermore, the United States, the European Union, Eastern Europe, Latin America, Japan and the Middle East collectively produce about one billion tires annually, with estimated accumulations of three billion in Europe and six billion in North America.
The following shows how sulphur is added to rubber to vulcanise it ....