Curing, rubber description

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. 

Crosslinked rubbers follow the same description presented for thermoplastic compounds. A major problem with the use of organic pigments and dyes is that many decompose when high temperature curing agents are used. For these compounds, inorganic pigments are typically the only option. 

Beyond the particular process of cure in this case, the important problem which should not be neglected is the bonding of the rubber to the metal. This problem of adhesion of rubbers to metals is very weU covered in Reference [27] where a full description of the various tests is given. Another case of interest appears with the cure of a rubber when the cure is bound to various fabrics in order to get proofed materials such as hose. 

It is of utmost importance to operate the liquid silicone cavities at the lowest possible temperature that allows sufficient curing times for the rubber but which will not harm the plastic substrate. A qualitative description is shown in Figure 11.6. 

The advantages are outlined of the use of peroxide vulcanising agents in place of sulphur curing for elastomers. The chemistry of both types of vulcanisation systems is explained. Since the chemical mechanisms of each are very different, mbber compounders, experienced in the use of sulphur are reported to often find difficulties in formulating new products which make use of peroxide curatives. An overview is presented of the types of peroxides available and their properties. A description is included of the chemistry by which peroxides vulcanise rubber, followed by a discussion of the potential chemical interferences which may face rubber compounders converting from sulphur vulcanisation to peroxide curing. USA... 

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