Rotational isomeric state theory has been used to calculate mean-square unperturbed dimensions (r2>0 and dipole moments (/~> of ethylene-vinyl chloride copolymers as a function of chemical composition, chemical sequence distribution, and stereochemical composition of the vinyl chloride sequences. As was previously found for several other copolymeric chains, (/z2> is much more sensitive to chemi...

Vinyl cations, the dicoordinated unsaturated analogues of trivalent carbenium ions, were first detected by Grob and coworkers in the early 1960s in solvolysis reactions of a-aryl vinyl halides. In the 1970s numerous investigations established vinyl cations as reaction intermediates in solvolysis reactions of activated alkenyl halides and in reactions of electrophiles with alkynes. The direct NM...

The carcinogenicity of vinyl chloride for experimental animals when administered transplacentally is reviewed in comparison with known transplacental carcinogens, including those that, like vinyl chloride, are dependent on enzyme-mediated metabolic conversion to a reactive intermediate in maternal or fetal tissues. Vinyl chloride is converted by mixed-function oxidases to the reactive metabolit...

objective(s): three-dimensional structures such as nanofibrous scaffolds are being used in biomedical engineering as well as provide a site for cells to attach and proliferate leading to tissue formation. in the present study, poly(vinyl pyrrolidone) (pvp)/ poly(vinyl alcohol)(pva) hybrid nanofibrous scaffold was synthesized by electrospinning. materials and methods: the effect of adding nano h...

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Unsaturated polyester and epoxy vinyl ester resins have broad utility in composite applications. Today’s commercially available premium thermal performance vinyl ester resins are derived from novolac epoxies and methacrylic acid. These products combine low viscosity with shelf stable, yet fast curing properties, and enable fabricators to manufacture composite parts with rapid throughput for dem...

The reactivities of alkaline NH(2)OH and neutral NaHSO(3) with carbonyl and olefinic groups conjugated with the tetrapyrrole nucleus of haems were studied. The reactions were carried out with 2-3nmol of haem a, spirographis haem, isospirographis haem, 2,4-diacetyldeuterohaem and protohaem. Vinyl side chains were found to be insensitive to the chemical action of both alkaline NH(2)OH and neutral...

A 48-h treatment with vinyl acetate (0.05-1 mM) induced a drastic increase in sister chromatid exchanges (SCEs) and (in first division cells) structural chromosome aberrations in cultured human lymphocytes. The effects were more pronounced in cultures of isolated lymphocytes than in whole-blood cultures. A distinct dose-dependent induction of SCEs similarly occurred in Chinese hamster ovary cel...

The thermal decomposition of 86 % vinyl chloride 14 % vinyl acetate copolymer wasstudied by the conductometry technique in the presence of nitrogen. The kinetics of stability andthermal degradation of vinyl chloride- co- vinyl acetate (PVC- co- PVAc) copolymer withcopper, copper oxide and tricalcium dicitrate (st) were investigated at various temperatures (150-180 oC ) in solution. The rate coe...