Influence of silica content on migration of antidegradants to the surface in NR vulcanizates

✍ Scribed by Sung-Seen Choi

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 288 KB
• Volume: 68
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19980613)68:11<1821::aid-app13>3.0.co;2-x

✦ Synopsis

Migration of antidegradants to the surface in silica-filled natural rubber (NR) vulcanizates was studied with migration-generating equipment using a vacuum technique. 2,6-Di-t-butyl-4-methyl phenol (BHT), N-phenyl-N-isopropyl-p-phenylenediamine (IPPD), N-phenyl-N- (1,3-dimethylbutyl-p-phenylenediamine (HPPD), and wax (n-C 23 H 48 , n-C 24 H 50 , n-C 25 H 52 , and n-C 26 H 54 ) were employed as antidegradants. The migration rate was found to be dependent on the content of silica in the vulcanizates. IPPD migrates faster than BHT and HPPD irrespective of the content of silica. BHT migrates faster than HPPD at 60 and 80ЊC, but slower than HPPD at 100ЊC. The migration rates of BHT, IPPD, and HPPD decrease with increase of the silica content from 30 to 70 phr. Wax with a low molecular weight migrates faster than that with a high molecular weight. The migration rate of n-C 23 H 48 , irrespective of migration temperature, decreases with increase of the silica content, similar to BHT, IPPD, and HPPD, but those of n-C 25 H 52 and n-C 26 H 54 have a local maximum at 50 phr silica content. The activation energies for migration to the surface in the vulcanizate containing 50 phr of silica are 19.