Chemically curing systems, reversibility

The optimising of a tyre compound to improve reversion resistance is discussed with reference to the use of two new rubber chemicals developed by Flexsys. They are 1,3 bis(citraconimidomethyl benzene) (BMI-MX) and hexamethylene-1,6-bisthiosulphate disodium salt dihydrate (HTS), which are claimed to provide two different ways to improve the thermal ageing resistance of sulphur-based vulcanisates as compared to existing technology. Each functions by uniquely different mechanisms of action and each provides different levels of performance improvements. A comparison is made of HTS and BCI-MXto conventional cure systems and semiefficient cure systems to illustrate the potential benefits of these approaches to address reversion in tyre compounds. 5 refs. 

Reactive systems (liquid components) curing (chemical or radiation initiated reactions) thin to very high thickness high cohesion good reversibility low tack on rough substrates... 

The heat-resistant nature of NR vulcanizates containing very high proportions of monosulfide crosslinks (as obtained from an adequately cured efficient vulcanization system) is now well known. However, the thermal stability of these monosulfide-crosslinked networks is still about an order of magnitude lower than the stability of carbon-carbon crosslinked NR, which shows only very slow modulus reversion even at 200 °C (Figure 2). An extensive investigation of the chemical reactivity... 

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