Antiozonants, rubber classes

FAB has been used to analyse additives in (un) vulcanised elastomer systems [92,94] and FAB matrices have been developed which permit the direct analysis of mixtures of elastomer additives without chromatographic separation. The T-156 triblend vulcanised elastomer additives poly-TMDQ (AO), CTP (retarder), HPPD (antiozonant), and TMTD, OBTS, MBT and A,lV-diisopropyl-2-benzothiazylsulfenamide (accelerators) were studied in three matrix solutions (glycerol, oleic acid, and NPOE) [94]. The thiuram class of accelerators were least successful. Mixture analysis of complex rubber vulcanisates without chromatographic separation was demonstrated. The differentiation of matrix ions from sample ions was enhanced by use of high-resolution acquisition. 

Zinc dialkyl dithiocarbamates reduce the rate of crack growth, but their scorch resistances are prohibitively low. A few other classes of compounds have been reported to react rapidly with ozone, such as phosphines and stibines. These materials also exhibit antiozonant activity when swollen into rubber vulcanizates after the cure. However, they cannot be used practically for two reasons ... 

The PPD class of antidegradants provides by far the best antiozonant protection (for a review of antiozonants, see Reference 82). PPDs inhibit ozone degradation of rubber by multiple mechanisms (76,83-85) ... 

PPD is the highest volume antiozonant used today by the rubber industry. Millions of pounds of this antiozonant are used annually. It is of the alkyl aryl p-phenylene diamine class of antiozonant. Because of its solubility characteristics in compounds... 

DPPD is a very commonly used antioxidant of the diarylphenylene diamine class. DPPD is relatively less expensive than PPDs of the alkyl-aryl or alkyl-alkyl class. On the other hand, DPPD is also not as reactive with ozone and possesses lower solubility in rubber, which causes it to form an undesirable bloom more readily than the other antiozonants. DPPD is a widely used antioxidant however, its use as an antiozonant is much smaller. 

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