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41.
In Part I of the paper ((1999), Trib. Trans., 42, pp. 851–859) we investigated the effect of the polyethylene concentration on the film forming properties in a rolling bearing. This second part presents the influence of the polymer additive concentration on the traction behavior experienced using a two-disk machine at different temperatures and contact pressures. By using the traction data, a semi-empirical approach for determining the effective lubricant theological parameters in EHL contacts was performed. Using this approach, the effect of polymer concentration upon rheological parameters that appear in the Johnson and Tevaarwerk model with Eyring stress was quantified. 相似文献
42.
Clotilde Minfray Thierry Le Mogne Jean-Michel Martin Tasuku Onodera Sayaka Nara Shuko Takahashi 《摩擦学汇刊》2013,56(5):589-601
Zinc phosphate glass is considered to be the main constituent of tribofilms generated under boundary lubrication with zinc dialkyldithiophosphate (ZDDP), a well-known antiwear additive. The reaction occurring during friction between zinc phosphate glasses and steel native iron oxide layer is investigated by both an experimental approach and by Molecular Dynamics simulations (MD). The importance of this “tribochemical” reaction in the general ZDDP antiwear process is discussed. 相似文献
43.
The effect of pH,salts and sugars on the rheological properties of cress seed (Lepidium sativum) gum
Fataneh Behrouzian Seyed M. A. Razavi Hojjat Karazhiyan 《International Journal of Food Science & Technology》2013,48(12):2506-2513
Effect of shear rate (15–600 s?1), gum concentration (1–2%), pH (3–9), sucrose (10–40%), lactose (5–15%), NaCl (100–300 mm ) and CaCl2 (5–50 mm ) was evaluated on apparent viscosity (ηa), flow behaviour index (n), consistency coefficient (K) and yield stress (τ0) indices of cress seed gum (CSG) solutions. Different rheological models were used to fit the experimental data, although the Herschel–Bulkley model was found the best model. An increase in gum concentration led to an increase in τ0, ηa, and k and a decrease in n values. The addition of salts lowered the k value; however, the n value showed slight significant change. The presence of sugar resulted in the enhancement of n, k, τ0 and ηap values. The existence of yield stress and pseudoplastic behaviour of CSG, its stability against salts, wide range of pH and synergic effect of sugar make it a good thickener and stabiliser in food formulations. 相似文献
44.
《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2013,30(9):1474-1484
ABSTRACTWe performed a safety evaluation using the procedure devised by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) of the following four flavouring substances that belong to the class of ‘aliphatic primary alcohols, aldehydes, carboxylic acids, acetals, and esters containing additional oxygenated functional groups’ and are uniquely used in Japan: butyl butyrylacetate, ethyl 2-hydroxy-4-methylpentanoate, 3-hydroxyhexanoic acid and methyl hydroxyacetate. Although no genotoxicity study data were found in the published literature, none of the four substances had chemical structural alerts predicting genotoxicity. All four substances were categorised as class I by using Cramer’s classification. The estimated daily intake of each of the four substances was determined to be 0.007–2.9 μg/person/day by using the maximised survey-derived intake method and based on the annual production data in Japan in 2001, 2005 and 2010, and was determined to be 0.250–600.0 μg/person/day by using the single-portion exposure technique and based on average-use levels in standard portion sizes of flavoured foods. Both of these estimated daily intake ranges were below the threshold of toxicological concern for class I substances, which is 1800 μg/person/day. Although no information from in vitro and in vivo toxicity studies for the four substances was available, these substances were judged to raise no safety concerns at the current levels of intake. 相似文献
45.
Violeta T. Pardio Krzysztof N. Waliszewski Paula Zuñiga 《International Journal of Food Science & Technology》2011,46(2):305-314
Biochemical, microbiological and sensory changes during shelf‐life at ?1 °C were determined in shrimp (Panaeus aztecus) previously dipped in ascorbic acid, citric acid, potassium sorbate and 4‐hexyl resorcinol solutions using face‐centred central composite design. Microbiological count, trimethylamine and hypoxantine production were measured. The lowest level of the total psychrotrophic bacteria, hypoxantine and trimethylamine were found in samples dipped in all containing chemicals solutions comparing to control treatment. Sensory studies showed that treatment A (ascorbic acid 4.50, citric acid 0.12, potassium sorbate 18.60 and 4‐hexyl resorcinol 0.25, all g L?1) and B (ascorbic acid 4.37, citric acid 1.26, potassium sorbate 7.03 and 4‐hexyl resorcinol 0.25, all g L?1) did not alter the typical sensory features of shrimp and were effective at delaying the bitter off‐flavour formation for 26 days. This study constitutes a promising alternative to extent shelf‐life of shrimp kept at ?1 °C without freezing. 相似文献
47.
Hiroyuki Hamada Hiroyuki Kato Naoto Ito Yoshihiko Takase Hironobu Nanbu Shoko Mishima Hiromu Sakaki Kiyotaka Sato 《European Journal of Lipid Science and Technology》2010,112(12):1323-1330
Biodiesel fuels (BDF) have many problems in the cold due to their crystallization properties. In particular, precipitation of large crystals of high‐melting fractions in BDF at low temperatures remarkably changes cold flow property of BDF and, thereby, it increases the values of cold filter plugging point. In this study, we evaluated polyglycerol esters of fatty acids (PGE) and ethylene‐vinyl acetate co‐polymer (EVA) as chemical additives to improve the cold flow property of palm oil‐based FAME (PFME). The results of solid fat content measurement indicate that the simultaneous addition of PGE and EVA showed synergistic effects on suppression of crystallization of PFME, however such effect was not observed when EVA was used alone. DSC thermograms indicated that the PGE additives not only decreased the crystallization temperature but also kinetically suppressed the crystal growth. Polarized light microscopy showed that the simultaneous addition of PGE and EVA led to the formation of considerably small and fine‐dispersed crystals of PFME. These results indicate that combined effects of PGE and EVA caused the formation of fine‐dispersed PFME crystals, which could improve the viscous properties of palm oil‐based BDF at relatively cold temperatures. 相似文献
48.
水基压裂液添加剂的应用与评价 总被引:7,自引:2,他引:5
本文综述水基压裂液稠化剂、交联剂、降滤失剂、破胶剂、粘土稳定剂、助排剂等主要添加剂在我国的研究、应用性能与评价,简要介绍了其它各种添加剂。 相似文献
49.
A modified Wilhelmy balance technique using thin fibers as solid probes has been applied to study the effect of silicone additives in acrylic resin-based powder coatings on the surface tension of non-reactive binder systems. By measuring the temperature dependence of the surface tension in the temperature range between 140 and 180°C, it could be shown that the silicone additives investigated had a very different surface activity in the molten acrylic resin. Due to the high accuracy of the measuring technique and the good reproducibility of the experiments the influence of different additive concentrations on the surface tension was detectable even at very low concentrations (below 1 wt.%).
Compared to the pure powder coating binder which has a surface tension of about 30 mN/m the values decreased between 2–15 mN/m depending on the type of the silicone additive. In addition, the temperature coefficient −(dγ/dT) of the surface tension of the binder melt was changed. In the case of two additives, the surface tension of the powder coating and its temperature coefficient were lowered considerably. This effect of additives is desirable to reach good wetting and leveling of the powder coating. 相似文献
50.
The load-carrying capacity, friction and wear properties of three (2-sulfurone-benzothiazole)-3-methyl esters added to a synthetic lubricant (triester) were evaluated using a four-ball tester and a ring-on-block machine. The results indicate that these compounds added to the triester possess good load-carrying capacities and antiwear properties. The rubbed surface was investigated by X-ray photoelectron spectroscopy (XPS). The analysis indicates that a lubricating film is formed on the metal surface by adsorption and chemical reaction. 相似文献