Use this URL to cite or link to this record in EThOS:
Title: Mechanisms of antifatigue agents used in natural rubber
Author: Sugimoto, Kenichi
Awarding Body: University of Aston in Birmingham
Current Institution: Aston University
Date of Award: 1995
Availability of Full Text:
Access from EThOS:
Access from Institution:
A large number of compounds containing quinonoid or hindered phenol functions were examined for their roles as antifatigue agents. Among the evaluated quinones and phenols expected to have macroalkyl radical scavenging ability, BQ, TOC, TOC and GM showed relatively good performance for fatigue resistance (although their performance was slightly less effective than the commercial aromatic amine antioxidants, IPPD and 6PPD). The compounds which were shown to have higher reactivity with alkyl radicals (via calculated reactivity indices) showed better fatigue resistance. This fact supports the suggestion that strong alkyl radical scavengers should be also effective antifatigue agents. Evidence produced based on calculation of reactivity indices suggests that the quinones examined react with alkyl radicals on the meta position of the quinone rings producing phenoxyl radicals. The phenoxyl radicals are expected either to disproportionate, to recombine with a further alkyl radical, or to abstract a hydrogen from another alkyl radical producing an olefine. The regeneration of quinones and formation of the corresponding phenols is expected to occur during the antifatigue activity. The phenol antioxidant, HBA is expected to produce a quinonoid compound and this is also expected to function in a similar way to other quinones. Another phenol, GM, which is also known to scavenge alkyl radicals showed good antifatigue performance. Tocopherols had effective antifatigue activity and are expected to have different antifatigue mechanisms from that of other quinones, hence TOC was examined for its mechanisms during rubber fatiguing using HPLC analysis. Trimers of TOC which were produced during vulcanisation are suggested to contribute to the fatigue activity observed. The evidence suggests that the trimers reproduce TOC and a mechanism was proposed. Although antifatigue agents evaluated showed antifatigue activity, most of them had poor thermoxidative resistance, hence it was necessary to compensate for this by using a combination of antioxidants with the antifatigue agents.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: Applied Chemistry ; Chemical Engineering