Vulcanization of carboxylated nitrile rubber (XNBR) by a mixed zinc peroxide-sulphur system

✍ Scribed by Ibarra, L; Alzorriz, M

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 122 KB
• Volume: 49
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(200001)49:1<115::aid-pi317>3.0.co;2-x

✦ Synopsis

Vulcanization of carboxylated nitrile rubber (XNBR) with a mixed system based on zinc peroxide and sulphur accelerators produces materials with favourable mechanical properties because of the formation of ionic aggregates which give the vulcanized compounds a certain rigidity. These properties are drastically reduced by the effect of saturated ammonia vapour which plasticizes the ionic aggregates. This plasticization, however, is reversible and the aggregates can be regenerated by addition of a solvent, which results in recovery and even improvement of the original properties such as stress at constant deformation, tensile strength, crosslinking density and storage modulus.

The temperatures of the two transitions observed in the relaxation spectra, the glass transition of the polymer and the ionic transition corresponding to ionic aggregates, are displaced to higher values when ionic structures are regenerated.