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Studies of tetrazoles as rubber chemicals. II. Reactivities and antioxidation activities of reactive antioxidants based on tetrazoles
Author(s) -
Otomo S.,
Kobayashi Y.,
Sako T.,
Yamamoto Y.,
Yamashita S.
Publication year - 1984
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1984.070290109
Subject(s) - isoprene , natural rubber , chemistry , polybutadiene , electrophile , organic chemistry , steric effects , medicinal chemistry , polymer chemistry , catalysis , copolymer , polymer
The chemical reactivities of novel reactive antioxidants based on tetrazoles for carbon–carbon double bonds of liquid polybutadiene and their antioxidation activities toward isoprene rubber were evaluated. These antioxidants, i.e., 2‐substituted phenyl‐5‐(3′,5′ ‐di‐ tert ‐butyl‐4′‐hydroxyphenyl)tetrazoles (PHPT), were pyrolyzed in liquid polybutadiene at 160–170°C for 30 min to attach to rubber in extents of 61–85% of the nitrileimines formed from PHPT by 1,3‐dipolar addition reaction. The reactivities of PHPT followed the order p ‐Cl > m ‐Cl > H > p ‐CH 3 > m ‐CH 3 , p ‐OC 2 H 5 , suggesting that PHPT reacts with diene rubber in electrophilic reaction and p ‐derivatives exhibit higher contents of binding than m ‐derivatives due to steric hindrance. From oxygen absorption data, the antioxidation activities of PHPT for isoprene rubber vulcanizates followed the order m ‐Cl, m ‐CH 3 > H, p ‐Cl, p ‐Cl, p ‐CH 3 > p ‐OC 2 H 5 . Isoprene rubber vulcanizates, obtained after pretreatment with PHPT by heating, were extracted with acetone, followed by aging to show that there was good retention and appreciable antioxidation activities of PHPT, especially, p ‐CH 3 and p ‐Cl substituted PHPT.