الفهرس | Only 14 pages are availabe for public view |
Abstract The present work is devoted to the preparation of novel different aromatic amine moieties and evaluation of their activity as antioxidants for acrylonitrile-butadiene rubber NBR. In the first part, 2-propyl-, and 2-heptyl-, 1H-benzo[d]imidazole (3a,b) were prepared by condensation reaction of o-phenylenediamine (1) with n-butanoic acid (2a) and n-octanoic acid (2b), respectively. The prepared products were characterized by FT-IR, 1H-NMR spectroscopy and melting points. These products were incorporated into (NBR) composites with two different fillers (Silica and High Abrasion Furnace carbon black “HAF”) as antioxidant additives at different concentrations from 1 up to 2 phr as compared to 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ) as a commercial antioxidant. Their effects on the rheometric, physico-mechanical and electrical properties of NBR composites were evaluated. Thermo-oxidative aging was carried out for NBR composites and distribution of the prepared products observed by Scanning Electron Microscope (SEM). Swelling and crosslinking density for NBR vulcanizates were evaluated and thermal gravimetric analysis (TGA) for NBR vulcanizates were also evaluated. The results showed that the prepared products can act as highly efficient antioxidants in acrylonitrile butadiene rubber vulcanizates comparing with commercial antioxidant TMQ and revealed that there was enhancement in mechanical properties of NBR composites that containing the prepared products, as well. The results also illustrated that the optimum ratio from 2-alkyl benzimidazoles incorporated into acrylonitrile butadiene rubber vulcanizates is 1.5 phr if compared with the same ratio from commercial antioxidant (TMQ). In the second part, 1H-benzo[d][1,2,3]triazole (4) as N- heterocyclic compound was prepared by ring closure reaction of diazonium salt of ophenylenediamine (1) by nitrous acid. FT-IR, 1H-NMR spectroscopy and melting point confirmed the successful preparation of 1H-benzo[d][1,2,3]triazole. The main objective of this study is to investigate the probability of 1Hbenzo-[ d][1,2,3] triazole to be used as a novel antioxidant for (NBR). The prepared product filled in NBR composite with different content starting from 1 to 2 phr as compared to the commercial antioxidant (TMQ). The mechanical, thermo-oxidative aging and electrical properties of the composites containing the prepared product were compared with those of composites having commercial antioxidant in the same content. Distribution of the antioxidants into composites was observed by (SEM). Swelling and crosslinking density for NBR vulcanizates and (TGA) analysis for NBR vulcanizates were also evaluated. The results revealed that 1H-benzo- [d][1,2,3]triazole can act as highly efficient antioxidant in acrylonitrile butadiene rubber vulcanizates comparing with commercial antioxidant TMQ and showed that there was enhancement in mechanical properties of NBR composites, as well. Keywords 2-propyl-1H-benzo[d]imidazole, 2-heptyl-1H-benzo[d]imidazole, 1Hbenzo[ d][1,2,3]triazole, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), Antioxidant, Physico-mechanical, Crosslinking density and Electrical properties |