State of the Art of polymer research in India. Part I. Modification of polymers by grafting

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Kinetics of Oxidation of Acetaldehyde, Propionaldehyde & n-Butyraldehyde by Peroxydiphosphate

420-42

Kinetics of Self-decomposition of Peroxydiphosphate in Aqueous Sulphuric Acid Medium

35-3

Oxidation of pyruvic acid by Cobalt (III)

The kinetics of oxidation of pyruvic acid sodium pyruvate by Co3+ in sulphuric and nitric acid media, and the effects of [ Co2+], [So3 4-] and temperature on the reaction rates have been studied. The reaction is biomolecular, the order with reference to [substrate] and [Co3+] being unity. The reaction rates vary inversely with [H+]. Increased in ionic strength and [HSO-4] retards the rates. From the result of kinetic studies it is inferred that CoOH2+ ions are active in HNO3 medium while in H2SO4 medium Co3+ ions also are active along with CoOH2+ ions. The stoichiometry of the reaction has been found to be 2Co2+ per mole of organic substrate ; acetic acid and carbon dioxide are the products. A free radical reaction mechanism involving fission at caorbonyl group folllowed by subsequent oxidation of carbonyl free radical to acetic acid has been proposed and the rate laws derive. The various reaction rate parameters have been evaluated and discussed

Silico acrylic finish

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Photo oxidation of iso propanol by uranyl perchlorate in aqueous acid medium

Photochemical oxidation of isopropanol by uranyl percholate in aqueous perchloric acid (1.0 M) was studied with visible light of wavelength 436 mμ at 35˚ C.The reduction was followed by measuring the rate of uranous ion production which was found to be proportional to light intensity and to light absorption fraction by the active species .Hydrogen ion concentration, ionic strength, initially added U4+ Decreased the rate slightly Acting as an internal filter. Formation of an intermediate complex between uranyl ion and isopropanol is suggested. Excitation of the complex by light in a primary photochemical act and decomposition of the excited complex by electron transfer mechanism in the dark are suggested to explain the mechanisms of oxidation

Vegetable tannings - a review

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Photo-initiated free radical polymerization of methyl acrylate in aqueous solution

Photo-initiated free radical polymerization of methyl acrylate in aqueous solution is described. Using mainly light of wavelength 3650 Å and the ion pairs Fe3+OH− and Fe3+Cl− as photosensitizers the kinetics of polymerization were investigated by studying the effect of the variation of (i) intensity of light, (ii) concentration of monomer, (iii) fraction of light absorbed by the ion pair, and (iv) ferrous ion accumulating in, or initially added to, the system on (a) molecular weight of polymer, (b) the rate of disappearance of monomer, and (c) the rate of production of ferrous ion. The results have been analyzed in the light of a reaction scheme involving (1) a primary photochemical process and a dark back reaction, (2) initiation of polymerization by the primary product Fe2+OH or Fe2+Cl, (3) dissociation of the primary product, (4) a secondary dark back reaction, (5) initiation by a free radical, (6) propagation, and (7) termination. Examination of the experimental results in the light of the reaction scheme indicated that the initiation of polymerization was due to OH or Cl free radicals formed by the dissociation of the primary product and that termination occurred by combination of growing polymer chains. Some expressions involving specific rate constants have been evaluated

Phosphorous compounds in leather industry

The possible applications of phosphorus compounds in leather-making are reviewed. Polyphosphoric acid or its salts are used as (a) pretanning agent in vegetable tanning and (b) pretanning or retaining agent or complexing component in chrome lanning, Polyphosphates are also water softeners, The phospho-compound tetrakis (hydroxy methyl) phosphonium chloride is a good tanning agent in the presence of resorcinol. Phosphatides and alkyl phospho-esters are complexing lubricants. Chrome complexes of alkyl phosphoesters are water proofing-agents. Phospho-acrylates are good additives to acrylic finishes for impairing flame-proof characterstics. Poly-fluoro alkyl phosphates impart oil repellent characterstics in leathers. Triaryl phosphates are good plasticisers for vinyl and cellulosie finishes; they are also flame-retardents

Defects in hides and skins that fect assessment

The defects in raw hides and skins procured from different parts of the country vary considerably in view of the variations in climate and other environmental conditions. Proper identification of the most common defects, therefore assumes much significance in evolving standardized procedures for assessing quality of raw hides and skins. Reference may be due to IS: 7656-1975 Code of practice for curing and preservation of cattle hides and goal and sheep skins by et salting method which gives improved methods of curing and preservation as also precautions to avoid defects in hides and skins