نتایج جستجو برای: antioxidants and DSC
تعداد نتایج: 16830380 فیلتر نتایج به سال:
To obtain novel structural antioxidants that have different antioxidant mechanisms, four 2-(alkylthio)-N-(4-(phenylamino)phenyl)acetamides 2a-d as dual functional antioxidants are designed, synthesized, and confirmed by ¹H-NMR, FTIR, MS, and elemental analysis. The antioxidant behavior of compounds 2a-d as additives of base oil triisodecyl trimellitate (TIDTM) is evaluated by non-isothermal and...
The radical-scavenging activities of two thiols, eight (thio)barbituric acid derivatives and six chain-breaking phenolic antioxidants were investigated using the induction period method for polymerization of methyl methacrylate (MMA) initiated by thermal decomposition of 2,2’-azobisisobutyronitrile (AIBN) and monitored by differential scanning calorimetry (DSC). The induction period (IP) for th...
Four liquid crystal compounds of the form, 2-Sec-butyl-4-[(4-x-phenyl) diazenyl) phenyl-4-(octadecyloxy] benzoate symbolized as I18a, I18b, I18c and I18d were prepared in which the substituent (X) was taken CH3O-, CH3-, Br- and -NO2 respectively. Characterization of prepared compounds is done using FT-IR, 1H-NMR, Mass Spectroscopy and Elemental Analysis.. Their mesophase behavior was investigat...
Recently, thermoanalytic methods have frequently been used in the characterization of oils and fats. In this work, thermoanalytic and kinetic parameters of sunflower oils, with and without antioxidants, were evaluated using thermogravimetry / derivative thermogravimetry and differential scanning calorimetry. The thermogravimetric profiles for the sunflower oils had similar characteristics, show...
The antioxidant and antimicrobial activity of methanol or dichloromethane extracts of O. dictamnus, produced from wild and organic cultivated specimens, were determined. The Rancimat and malondialdehyde (MDA) by HPLC methods were used to measure the antioxidant action, in comparison with that of the common commercial antioxidants butylated hydroxytoluene (BHT) and alpha-tocopherol. The extracts...
The radical-scavenging activities of the synthetic antioxidants 2-allyl-4-X-phenol (X = NO2, Cl, Br, OCH3, COCH3, CH3, t-(CH3)3, C6H5) and 2,4-dimethoxyphenol, and the natural antioxidants eugenol and isoeugenol, were investigated using differential scanning calorimetry (DSC) by measuring their anti-1,1-diphenyl-2-picrylhydrazyl (DPPH) radical activity and the induction period for polymerizatio...
The eciency of various commercial hindered phenol antioxidants was studied using dierential scanning calorimetry (DSC) to determine the oxidation induction time (OIT) of antioxidant solutions in squalane. It was observed that a-tocopherol has an exceptionally high antioxidant activity. In fact, after normalisation for the molecular weight and functionality of each antioxidant, a-tocopherol wa...
heteropoly acids (hpa) and their salts have advantages as catalysts which make them both economically and environmentally attractive, strong br?nsted acidity, exhibiting fast reversible multi-electron redox transformations under rather mild conditions, very high solubility in polar solvents, fairly high thermal stability in the solid states, and efficient oxidizing ability, so that they are imp...
Abstract This study demonstrates that bio-based products of lignin depolymerisation can potentially replace common antioxidants and UV absorbers in the plastics cosmetics industries. The kraft Indulin AT was used to obtain low-MW monomers & oligomers rich phenolic hydroxyl groups. Both thermo-oxidative stability antioxidant activity significantly improved upon depolymerisation. results from...
Suberin is present in the underground parts of vegetables and in the bark of trees. Characterization of suberin and the structure of its polyphenolic component have been hampered by insolubility of the polymers. Thus, enzymatically isolated and extractive free suberin enriched fraction from potato, Solanum tuberosum var. Nikola, and the chemically further fractionated phenolics were characteriz...
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