Over the last 150 years technologists and chemists in the rubber industry have developed materials that are highly durable, and resistant to temperature, aggressive environments and irradiation. As a consequence products have been created that give very high performance and long life. This advantage from the consumers' perspective creates problems when it comes to disposal at the end of the items life. It also presents the same problems when dealing with the normal in-process waste produced in the factory. Thermoplastic processors can recycle their flash, runners and off-spec products, but this route has not been available to the conventional rubber processor. To date attempts have not been able to develop a technology that is able to render the material amenable to reprocessing and to give a high level of physical properties such that the re-used material is comparable to virgin material with its associated high added value. Most techniques have either broken the material down mechanically so that it can be incorporated as a filler with a consequent lowering of physical properties or in their attempt to break the cross-links have degraded the polymer at the same time to yield a low value additive that might claim to help with processing but little else. Although a range of devulcanisation technologies, such as those based on chemical agents and ultrasound, have been available since the 1980's, the drivers for their adoption have not to date been strong enough to encourage their widespread use. However, for the majority of end of life rubber components (volume-wise heavily dominated by tyres) and factory waste have traditionally gone to landfill. This disposal route is now environmentally unacceptable and this, together with economic pressures associated with the rising price of crude oil, has ensured that money and resources have been made available by both industry and governments to carry out additional research into novel devulcanisation technologies and the re-use of waste rubber.
展开▼
