Butadiene rubber sulfur vulcanisation

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. 

The accelerated sulfur vulcanisation of general purpose diene rubbers (e.g., natural rubber (NR), Styrene butadiene rubber (SBR), and butadiene rubber (BR)) in the presence of organic accelerators and other rubbers, which are vulcanised by closely related technology (e.g., ethylene-propylene-diene terpolymer (EPDM) rubber, butyl rubber (HR), halobutyl rubber (XIIR), nitrile rubber (NBR)) comprises more than 90% of all vulcanisations. 

Buna 85 is polybutadiene (the number represents Mooney viscosity), molecular weight -80,000. Hard rubber has high softening point and excellent chemical resistance. The coefficient of vulcanisation to the ebonite stage is 39.3. The coefficient of vulcanisation is the number of unit weight of sulfur combined with 100 units by weight of unsaturated hydrocarbons. Buna S is a butadiene styrene copolymer with 70/30 to 68/32 ratio. Buna SS contains a high proportion of styrene. Perbunan are nitrile rubbers... 

The monomer of natural rubber is 2-methyl-l,3-butadiene, which is very similar to the monomer for neoprene. The intermolecular forces between natural rubber polymers are van der Waals forces. A process called vulcanisation was invented to make rubber tyres more resilient and hardwearing. This links rubber polymer chains by covalent bonds across sulfur bridges (Figure 28.22). 

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