Acrylonitrile-butadiene rubber vulcanisation

In the past chemical cure linings have been employed on a wide scale. These linings, usually based on natural rubber or acrylonitrile-butadiene rubber consist of a standard lining compound with a chemical activator such as dibenzylamine incorporated in the formulation. Prior to the application of the lining to the substrate, the individual sheets of rubber are dipped or brush coated with carbon disulphide or a solution of a xanthogen disulphide in a solvent. The carbon disulphide or xanthogen disulphide permeates the rubber and combines with the dibenzylamine to form an ultra-fast dithiocar-bamate accelerator in situ, and thus the rubber rapidly vulcanises at ambient temperature. 

In more recent years, lining compounds have been developed that vulcanise at ambient temperatures. Most polymers can be used for such compounds, although most materials are based on natural rubber, acrylonitrile-butadiene rubber and polychloroprene. These compounds contain accelerators which usually give rise to a material which has a delay in the onset of vulcanisation with a subsequent rapid rise in cross-link formation to give full vulcanisation in 6 to 8 weeks. Such materials, unless to be used within a few days of manufacture, are refrigerated to arrest the sel f-vulcanisation. 

Yamada and co-workers [59] pointed out that spectroscopic methods such as IR spectroscopy and NMR spectroscopy previously used in sequencing studies on ethylene-propylene-diene and hydrogenated acrylonitrile butadiene rubbers often encountered the same difficulties experienced with the analysis of vulcanised rubbers, i.e., their insolubility. 

A mixed polymer of butadiene and acrylonitrile (Perbunan, Hycar, Chemigum) may be vulcanised like rubber and possesses good resistance to oils and solvents in general. 

Yong, K.C. and Saad, C.S.M. (2010) High temperature-mechanical mixing to prepare electrically conductive sulfur-vulcanised poly(butadiene-co-acrylonitrile)-polyaniIine dodecylbenzenesulfonate blends. J. Rubber Res., 13,1-17. 

Results are presented of investigations of the effect of cationic surfactants of the above type, at levels of 0.1 to 2.5 parts per 100 parts rubber, on the kinetics of sulphur vulcanisation of polyisoprene rubber and butadiene-acrylonitrile rubber and on the properties of the vulcanisates. It is shown that these quaternary ammonium compounds shorten the process of sulphur vulcanisation of diene elastomers, increase the effectiveness of their crosslinking and improve the strength properties of vulcanisates, but also result in a reduction in the time before the start of vulcanisation, which can lead to scorching of the rubber mixes. 4 refs. (Full translation of Kauch.i Rezina, No.3, 1995, P-17)... 

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