Migration behaviors of antiozonants to the surface in NR vulcanizates, depending on the season: The effect of wax

Influence of wax film on the surface of a rubber vulcanizate on migration o f antiozonants was studied using NR vulcanizates containing various types o f waxes. The waxes have different molecular weight distributions. N-phenyl- N'-isopropyl-p-phenylenediamine (IPPD), N-phenyl-N'-(1,3-dimethylbutyl)-p-p henylenediamine (HPPD), N,N'-di(sec-butyl)-p-phenylenediamine (SBPPD), and N,N'-di( 1,4-dimethylpentyl)-p-phenylenediamine (DMPPD) were used as antioz onants. Migration experiments were performed outdoors for two months in the summer, fall, and winter. The migration rates of the antiozonants in the v ulcanizate without wax are faster than those in the vulcanizates with waxes . The antiozonants migrate slower in the vulcanizate containing wax with a high-molecular-weight distribution than in the vulcanizate with a low one. In the summer, the migration rates of SBPPD and DMPPD are faster than those of IPPD and HPPD, respectively. But, in the fall, the migration rates of S BPPD and DMPPD are slower than those of IPPD and HPPD, respectively. The di fferences of migration behaviors of the antiozonants, depending on season a nd wax type, was discussed. (C) 1999 John Wiley & Sons, Inc.