Comparative Assessment of the Efficiency of Antioxidants for Cis-1,4-Polyisoprene

Abstract

At present, cis-1,4-polyisoprenes of grade SKI-3 (GOST 14925-79) and SKI-3S (TU 2294-022-48158319-2001) are being produced in Russia. The antioxidants used for their stabilisation are given in Table 1. Antioxidants DPPD, Diaphen 13, Santofl ex 134 PD, Flexon 11L, and Dusantox L comprise N,N′-substituted p-phenylenediamines or their mixtures [1, 2]. These products are produced by various companies and are imported. Apart from DPPD, they are liquids with good solubility in toluene, and Santofl ex 134 PD, Flexon 11L, and Dusantox L have fairly good solubility in an isopentane-isoprene mixture. VTS-60, S-789, and AFA-1 are home-produced antioxidants. VTS-60 and S-789 are also p-phenylenediamine derivatives. Antioxidant Novantox 8 PPDA is analogous to S-789 [3] but, unlike it, is produced from individual 2-ethylhexanol. Antioxidant AFA-1 is the condensation product of alkylphenol, urotropin, and N-isopropyl-N′-phenyl-p-phenylenediamine [4]. Agidol-1 comprises 2,6-di-tert-butyl-4-methylphenol. Agidol-2, Lovinox 22M46, and Ralox 46 are trade names for phenolic antioxidant 2,3-methylenebis(6-tert-butyl-4methylphenol) produced by various companies.