No abstract

The antioxidant performance of a sterically hindered bisphenol antioxidant, 4,4'-bis(2,6-di-tert-butylphenol), in model reactions of accelerated aging of carbon-chain polymers (polypropylene, isoprene rubber) was studied. This antioxidant was examined by differential scanning calorimetry and Wallace plasticity measurements in comparison with known commercial phenolic and amine stabilizers. High performance of 4,4'-bis(2,6-di-tertbutylphenol) as antioxidant was revealed.

Processes involving the removal of sulfur compounds from gases and liquid petroleum products are analyzed. Economic expediency of the implementation of low-waste methods of demercaptanization of gases, gasoline and kerosene cuts, gas condensates, and light crudes with the polymeric catalyst KSM is substantiated. A complex desulfurization flow plan, which permits maximum extraction of natural sulfur-organic compounds, lowering of the content of total sulfur in the light cuts, and improvement of hydrofinishing conditions of the heavy cuts is proposed. Demercaptanization of Light Hydrocarbon Stock -Demer-LHCSOf the existing methods employed for the demercaptanization of light hydrocarbon stock (LHCS), methods of the alkali extraction of mercaptans with regeneration of saturated mercaptides of the alkali solution by oxidation with atmospheric oxygen in the presence of a homogeneous [1], or heterogeneous [2] phthalocyanine catalyst have come into the most widespread use. Merpeisov et al. [3] propose a method for the alkali-free "dry" demercaptanization of liquefied gases, gasoline, kerosene, gas condensates, and crude by passing the stock with air over an MARC catalyst via a filter with a catalyst, or by inducing contact between the product being treated and the stoichiometric amount of air directly in the flow of stock -in the pipelines and settling tanks. This method is non-regenerative, and in contrast to extraction methods of alkali treatment, does not permit recovery of mercaptans from gases and gasolines, i.e., reduction in the total-sulfur content of the latter. The catalyst in the homogeneous-catalyst process of alkali treatment [1] is dissolved or dispersed in the alkali solution, and circulates with it in the treatment system from the extractor to the regenerator, and back to the extractor. The presence of a catalyst in the alkali solution results in oxidation of the mercaptides with the formation of disulfides both in, and beyond the regenerator -in the pipelines and the extractor itself (due to the existence of residual oxygen in the regenerated alkali solution). The disulfides that are formed beyond the regenerator proceed into the extractor from the alkali in the product being treateded, increasing its total-sulfur content and liquid resid,

No abstract

The properties of heat stabilisers Bisphenol-5 [4,4′-bis(2,6-di- tert-butylphenol)] and Vulcanox BKF [2,2-methylene-bis(4-methyl-6- tert-butylphenol)] and their efficiency in stabilising nitrile butadiene rubbers (SKN-1865 and SKN-2665) were investigated. The efficiency of the antioxidants was assessed from the thermooxidative ageing of the rubbers at 150°C over the course of 1 and 3 h. The Mooney viscosity and solubility of specimens with Bisphenol-5 change less during oxidation than those of specimens with Vulcanox BKF. The good stability of the Bisphenol-5 dispersion after additional treatment in a ball mill for 12 h was shown. Stability was assessed from the sedimentation rate of antioxidant particles and from the ratio of sediment to dispersion volume. The vulcanisation time and physicomechanical properties of compounds based on rubbers containing Bisphenol-5 and Vulcanox BKF were compared. The recommended content of Bisphenol-5 in SKN-1865 rubber is 0.23 parts, and in SKN-2665 rubber 0.3 parts. Bisphenol 5 can be recommended as a replacement for imported Vulcanox BKF for the stabilisation of nitrile butadiene rubbers.