Vinyl acetate

About: Vinyl acetate is a research topic. Over the lifetime, 15970 publications have been published within this topic receiving 162142 citations. The topic is also known as: Ethenyl acetate & Ethenyl ethanoate.

Adhesive testing at the Canadian Conservation Institute-an evaluation of selected poly(vinyl acetate) and acrylic adhesives

Abstract: In 1983 the Canadian Conservation Institute (CCI) initiated a project to evaluate 27 poly(vinyl acetate) (PVAC) and 25 acrylic adhesives on the basis of pH, emission of harmful volatiles, flexibility/strength and yellowing upon dark aging at room temperature and fluorescent light aging. Measurement of the pH of extracts showed that the PVAC adhesives were more acidic than the acrylic adhesives and that light aging tended to decrease the pH of both classes. The PVAC homopolymers generally were more acidic than the PVAC copolymers and many acrylic adhesives containing butyl acrylate were found to be neutral. The analysis of volatile compounds from the PVAC and acrylic adhesives showed that they emitted various ester and residual solvent compounds but only the PVAC adhesives released appreciable quantities of acetic acid. The results indicated that, after an initial curing period of several weeks, the evolution of acetic acid from the PVAC adhesives should not pose an acute hazard. In general, both P...

Copolymerization of ω-Unsaturated Oligo(Methyl Methacrylate): New Macromonomers

Abstract: The free-radical copolymerization of ω-unsaturated oligo(methyl methacrylate) (1) with each of ethyl acrylate, styrene, methyl methacrylate, acrylonitrile, and vinyl acetate have been investigated. Incorporation of (1) into the polymer was observed in all cases although the molecular weights of the copolymers were substantially lower than those of the homopolymers obtained in the absence of (1) but under otherwise identical conditions. These experiments, together with a product study of the reactions of (1) with cyanoisopropyl radicals, have shown that the addition of free radicals to the double bond of (1) occurs readily. The sterically hindered radical so formed, however, undergoes facile β-scission, resulting in the termination of chains (chain transfer) in competition with chain propagation. The implications of these findings to the usefulness of (1) in the synthesis of graft copolymers and their relevance to the chemistry of free-radical polymerizations when methyl methacrylate is employed a...

Low permeability transparent packaging films

Abstract: A composite flexible transparent film structure comprises an organic polymeric base film carrying on one surface an adherent moisture resistant glassy continuous intermediate layer 0.02 to 2 microns thick of inorganic material which in turn carries a sealable adherent top coating of organic polymeric material. The base film may be of polyester, polyimide, copolymers of tetrafluoro-ethylene and hexafluoro-propylene, polyethylene, polypropylene, nylon, regenerated cellulose, or cellulose acetate. The inorganic material may be an oxide of silicon, zirconium, iron or aluminium, plumbous chloride, silver chloride or calcium silicate which may be deposited as a mixed oxide. The top coating may be of branched polyethylene, a vinylidene chloride copolymer, nitrocellulose, copolymers of vinyl acetate, or a polyamide. A spun bonded non-woven web may be laminated to and cover the top coating and a further layer of sealable top coating material is carired by the other surface of the base film. The inorganic layer may be formed by vacuum deposition on the base film and the top coating applied over the inorganic layer by melt extrusion.

Polyvinyl Alcohol in Medicine and Pharmacy: A Perspective

Abstract: Polyvinyl alcohol (PVOH) is a synthetic hydrophilic linear polymer that generally exists as a copolymer of vinyl alcohol and vinyl acetate. Therefore, the structural properties of PVOH polymers primarily depend on the degree of polymerization and the degree of hydrolysis, i.e., the ratio of the two monomers. Due to reactive functional groups on its structure, PVOH undergoes chemical changes such as esterification and etherification, as well as physical changes such as crystallization and ion-polymer complexation. Both chemically and physically-modified PVOH structures have found applications in biomedical and pharmaceutical area. This article reviews the properties of PVOH in solid and solution states, PVOH hydrogels and cryogels, their biomedical and pharmaceutical applications, and their potential challenges.