Devulcanisation technologies

Because of the dominance of sulfur-cured rubbers in the market, which is principally due to their use in manufacturing the single most important rubber product (i.e., tyres), the majority of the work that has been done on devulcanisation has concentrated on breaking the sulfur-sulfur crosslinks in these type of rubbers, and this is reflected in the information that is presented in Sections 4.3 to 4.9. Before the different devulcanisation technologies are described in detail, it is useful to consider the chemistry that is associated with these type of crosslinks, as it is this that has played such an important role in determining the fundamental choices that have been made with regard to the mechanisms that have been employed and the development work that has been carried out. 

Transfer of DevulC02 devulcanisation technology to sulfur-cured... 

The scale-up goal was achieved and the DevulCOi devulcanisation technology was successfully transferred to a number of sulfur-cured rubbers, including nitrile rubber, EPDM rubber and NR. In addition, the results of the evaluation of the performance of the DevulCOi rubber in tyre retread compounds were encouraging. A more extensive description of these two projects and the results of the manufacturing trials that were imdertaken during them, is provided in Chapter 5, Section 5.2.2.I. 

Evaluation of Waste Tire Devulcanisation Technologies, Report by CalRecovery Inc. for the Integrated Waste Management Board of California, December 2004. 

Chemicals that are used in the Levgum process and those that may work in a similar manner to this particular devulcanisation technology. 

W. C. Warner, Methods of Devulcanisation, Rubber Chemistry and Technology, Rubber Reviews, Rubber Division, American Chemical Society, Inc., Washington, D.C., 1994, pp. 559-566. 

This section will review the different technologies that are currently available for the devulcanisation of waste rubber from waste tyres, or from products in the general rubber goods (GRG) sector. Devulcanisation, although important, is only one way of recycling waste rubber and the extensive range of other technologies that have been developed for this purpose are covered in later sections of this book e.g., crumb manufacture and the use of crumb in the production of a variety of different products are reviewed in Chapters 6 and 7. 

Waste butyl rubber has been both devulcanised and re-revulcanised by workers in the East China University of Technology [21] under conditions of high shear and high temperature in a Haake Rheometer. They investigated the effect of the process temperature on the degree of devulcanisation and also compared the damping and physical properties of the waste rubber, DR and re-cured materials. 

The use of microwaves in conjunction with a chemical devulcanisation agent is a variation of this technology that assists the process to be more targeted towards the removal of crosslinks. In this variation of the technology, the microwaves are used to generate the heat to enable the devulcanisation reaction to proceed. 

Some of the earliest cited practical, third-party trials of DeLink were reported in Plastics and Rubber Weekly [6]. The article covered the official launch for DeLink at the International Seminar and Workshop on Devulcanisation Using DeLink R Process that was held at the TARRC laboratories (then MRPRA). Papers that were presented generally endorsed the claims made by STI-K that the rubber devulcanised by DeLink can be used in manufacture or blended with fresh rubber compound to obtain the desired levels of technological performance. Rubber that had been devulcanised with DeLink had been used successfully to ... 

The properties of the fine, devulcanised rubber crumb that results from the process varies according to the types of additives used and their levels, and the crumb has been shown to be used effectively to replace virgin rubber in new rubber compounds. For example, experimental trials have been undertaken with rubber crumb obtained using this technology from car tyre treads incorporated into SBR compounds. The results that were obtained on the resulting vulcanisates were compared to those produced using conventional rubber of the same... 

Rubber Chemistry and Technology 70, No.l, March/April 1997, p. 120-8 VULCANISATION OF ULTRASONICALLY DEVULCANISED SBR ELASTOMERS... 

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