recycling
The term recycling is used here as it is traditionally employed within the Rubber Industry. This is not to be confused with recycling using HSM technology.
Recycling of rubber is carried out by:
Reusing the original product is regarded as the most environmentally effective method of recycling as it often has the lowest impact on material resources, energy consumption and emissions from manufacturing. For a number of rubber products, such as tyres, the reusability of the product in its original form is limited by factors such as safety.
Reusing the product materials is regarded as the second best option from an environmental viewpoint. Technologies such as retreading enable most of the original product to be reused whilst the manufacture of barriers from compressed and baled tyres and shoe soles from stamped tyre tread are examples of alternative applications for these materials.
For a number of products, the ideal form of recycling would require the reversal of the vulcanisation process to provide a devlucanised material for re-use. As a generally accepted and economically viable solution to this problem has traditionally not been available, this area remains the focus of a number of research activities.
Results obtained from the HSM process indicate that a reversal of the crosslinked network takes place to provide materials that are reformable and recurable.
Although not total devulcanisation, most current commercial processes rely on a chemical "reactivation" of the surface of the vulcanised material. This process often requires the scrap material to be finely crumbed to increase the surface area before treatment.
By far the largest potential application for new rubber is in tyre manufacture (61%) but currently only limited amounts of recycled rubber is used in the manufacture of new tyres (typically 3 to 4% up to a maximum of 15%), primarily to improve wear resistance and to act as a process aid.
Current recycling technologies do not provide materials that sufficiently meet the performance requirements of modern tyre manufacture to enable new tyres to be made totally from recycled materials.
