Topic
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.
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Patent•
27 Oct 1945
TL;DR: In this paper, saturated and soluble solid ethylene polymerization products, e.g. the surface of films and coatings, are cured by incorporating therewith a curing agent by subjecting the polymerization product or articles prepared therefrom to the action of a solution of the curing agent in a non-solvent for the polymerisation product at the temperature employed, and then heating above 40 DEG C., preferably between 70 DEG and 250 DEGC.
Abstract: Saturated and soluble solid ethylene polymerization products, e.g. the surface of films and coatings, are cured by incorporating therewith a curing agent by subjecting the polymerization product or articles prepared therefrom to the action of a solution of the curing agent in a non-solvent for the polymerization product at the temperature employed, and then heating above 40 DEG C., preferably between 70 DEG and 250 DEG C. Specified ethylene polymerization products are polyethylene and interpolymers of ethylene with at least one other organic compound containing polymer-producing unsaturation, e.g. carbon monoxide, acrylic acid esters and nitrile, alkacrylic acids, esters and nitriles, vinyl acetate, propionate and chloride, vinylidene halides and maleic and fumaric acids and derivatives thereof. The curing agents are capable of generating free radicals below 200 DEG C. when heated, specified are benzoyl, lauroyl, diethyl, ditertiary butyl and diisopropyl peroxides, hydroxy-methyl, tertiary butyl and ethyl hydroperoxides, oxygen, aceto-, benzo-, phthalic and succinic mono-peracids, ethyl percamphorate and perbenzoate, tert.-butyl perbenzoate, chloramines B and T, dichloramine T, lead tetraethyl, lead diethyl dibromide, triethylamine oxide, hydrazine hydrate, hydrochloride and sebacate, dibenzoyl hydrazine, diphenyl ketazine and aldazines. The preferred solvents have a swelling action on the polymer at their boiling points or lower temperatures, suitable solvents are given in the Trans. Faraday Soc., v. XLII, parts 1 and 2, 1946, p. 22, xylene being preferred. The polymerization products may contain fillers, pigments and plasticizers, e.g. calcium carbonate, iron oxide and crown clay. Preferably, the heating step is carried out under superatmospheric pressure and by contact with a hot metal surface, e.g. a mould or press. The invention may be applied to the curing of preformed articles, e.g. mouldings, coatings, e.g. extruded on wires, films and fibres. Specification 597,833 is referred to.
73 citations
TL;DR: In this article, a methodology to produce highly porous cross-linked hydrogel materials by templating concentrated CO2-in-water (C/W) emulsions was presented.
Abstract: We present here a methodology to produce highly porous cross-linked hydrogel materials by templating concentrated CO2-in-water (C/W) emulsions. Poly(vinyl alcohol) (PVA), blended PVA/PEG, and naturally derived chitosan materials were produced via this route. The technique can be carried out at moderate temperatures and pressures (25 °C, <120 bar) using inexpensive hydrocarbon surfactants such as PVAc-based block copolymers which are composed of biodegradable blocks. This methodology opens up a new solvent-free route for the preparation of porous biopolymers, hydrogels, and composites, including materials which cannot readily be produced by foaming.
73 citations
TL;DR: In this paper, non-isothermal crystallization and subsequent melting of three grades of ethylene-vinyl acetate copolymer were investigated by differential scanning calorimetry (DSC) technique.
Abstract: Non-isothermal crystallization and subsequent melting of three grades of ethylene-vinyl acetate copolymer were investigated by differential scanning calorimetry (DSC) technique. The DSC crystallization curves show that vinyl acetate (VAc) content has the same effect on the onset, peak and final crystallization temperatures, and these copolymers have almost the same spacing of thermal windows under identical crystallization condition. Subsequent melting DSC results suggest that EVA14 (14 wt% VAc) has the narrowest distribution of lamellar thickness and the most perfect crystals. Though the instantaneous nucleation was preferred, non-isothermal crystallization kinetics shows that EVA14 could form tridimensional crystallites, whereas EVA18 (18 wt% VAc) and EVA28 (28 wt% VAc) are prone to crystallize two-dimen- sionally, as a result of more noncrystallizable VAc co-monomers introduced in the crystallizable ethylene segments. The growth rate falls on the following sequence: EVA14>EVA18>EVA28. Moreover, the kinetic crystallizability G also well characterizes the variation of the non-isothermal crystallization of these EVA materials, in the view of structural impedi- ment caused by the VAc content.
73 citations
TL;DR: A stabilizer-free dispersion polymerization with alkyl esters as reaction media gives uniform alternating microspheres of maleic anhydride (MAn)/vinyl acetate (VAc) copolymer as discussed by the authors.
Abstract: A novel, stabilizer-free dispersion polymerization with alkyl esters as reaction media gives uniform alternating microspheres of maleic anhydride (MAn)/vinyl acetate (VAc) copolymer. The diameter of the copolymer microspheres could be precisely controlled from 80 to 750 nm by changing the monomer concentration or feed ratio. Moreover, this new type of copolymer microspheres with reactive anhydride groups on the surface has good solubility in common nontoxic solvents such as water and ethanol.
73 citations
TL;DR: In this article, the potential of two types of reactions for reactive extrusion was evaluated in our laboratory: exchange reactions of copolyesters and free radical grafting of monomers onto polyolefins.
Abstract: The potential of two types of reactions for reactive extrusion was evaluated in our laboratory: exchange reactions of copolyesters and free radical grafting of monomers onto polyolefins. Specifically, the alcoholysis of ethylene and vinyl acetate copolymers, the transesterification of ethylene and alkyl acrylate copolymers (EAA) and the aminolysis of alkyl acrylate copolymers were investigated as the exchange reactions while the grafting of maleic anhydride (MA) onto polypropylene (PP) as the free radical reactions. The exchange reactions are very slow without catalysts. Tin derivatives, such as dibutyl tin dilaurate (DBTDL) and dibutyl tin oxide (DBTO), are good catalysts for the alcoholysis and the transesterification, but not for the aminolysis. For the latter, tautomeric compounds, such as 2-pyridone and 2-mercaptopyridone, are efficient. Comparative kinetic studies showed that, for all the three exchange reactions, the reacting medium (solution or the homogeneous melt) does not affect their reaction mechanisms nor their intrinsic rate constants. Additionally, mechanical mixing does not contribute to the overall reactions. As for the free radical grafting of MA, the presence of electron-donating monomers and styrene (ST) in particular was shown to be very effective in improving the grafting yield while minimising the degradation of PP. This was proven to be due to the formation of a charge transfer complex between MA and such a monomer.
73 citations