Showing papers on "Vinyl acetate published in 1979"

Mutagenic and alkylating metabolites of halo-ethylenes, chlorobutadienes and dichlorobutenes produced by rodent or human liver tissues. Evidence for oxirane formation by P450-linked microsomal mono-oxygenases.

Abstract: Mutagenicity, expressed as the number of his + revenants per μmole of test compound per hour of exposure, was estimated in two strains of S. typhimurium in the presence of a postmitochondrial mouse-liver supernatant, following exposure to vapours of one of a series of halo-olefins. Their activity was in the following descending order: 3,4-dichlorobutene-1 > 1-chlorobutadiene (technical grade) > 2-chlorobutadiene > vinyl bromide > vinylidene chloride > vinyl chloride; marginal mutagenicity was detected in the presence of 1,1,2-trichloroethylene and 1,1-difluoroethylene, and none with tetrachloroethylene and vinyl acetate. Liver fractions from humans converted vinyl chloride, vinyl bromide, vinylidene chloride and 2-chlorobutadiene into mutagens. In the plate incorporation assay, 1,4-dichlorobutene-2 was mutagenic per se, and addition of microsomal fractions from human or mouse liver enhanced the mutagenicity; a synthetic putative metabolite, 1,4-dichloro-2,3-epoxybutane was less mutagenic than the parent olefin in strain TA100. Treatment of rats with phenobarbital or 3-methylcholanthrene caused an up to 2-fold increase in the liver microsome-mediated mutagenicities of vinyl chloride and vinylidene chloride in S. typhimurium TA1530; while treatment with pregnenolone-16α-carbonitrile, aminoacetonitrile or disulfiram decreased the mutagenic effects. Vinyl chloride, and probably vinyl bromide, were shown to be epoxidized by mouse-liver microsomes; volatile alkylating metabolites were trapped by reaction with excess 4-(4-nitrobenzyl)pyridine and analysed spectrally. 2-Chlorobutadiene also yielded an alkylating intermediate, but 1,1-difluoroethylene, 1,1-dichloroethyleneand 1,1,2-trichloroethylene did not. 2-Chloro- and 1-chlorobutadiene, 3,4-dichlorobutene-1, 1,4-dichlorobutene-2 and its 2,3-epoxy derivative showed alkylating activity with 4-(4-nitrobenzyl)pyridine, which was not related quantitatively to mutagenic activity in S. typhimurium TA100 in the absence of a metabolic activation system. These data support the hypothesis that an oxidation of the double bond in certain halo-olefins, which is dependent on microsomal mono-oxygenases is a common pathway in the formation of biologically reactive intermediates. The relevance of the metabolites formed during such oxidative processes to the mutagenic, toxic and carcinogenic activities in vivo of some of the parent compounds is discussed.

Liquid emulsion polymers, process for preparing them and aqueous compositions thickened with these emulsions

Abstract: Novel aqueous liquid emulsion polymers are prepared by the copolymerization of (A) 15-60 weight percent of a C 3 -C 8 α,β-ethylenically unsaturated carboxylic acid monomer, preferably acrylic or methacrylic acid or a mixture thereof with itaconic or fumaric acid, (B) 15-80 weight percent of a nonionic copolymerizable C 2 -C 1 2 α,β-ethylenically unsaturated monomer, preferably a monovinyl ester such as ethyl acrylate or a mixture thereof with styrene, acrylonitrile, vinyl chloride or vinyl acetate, and (C) 1-30 weight percent of certain nonionic vinyl surfactant esters, such as nonyl- phenoxypoly (ethyleneoxy) 9 ethyl acrylate, to give an emulsion copolymer stable as an aqueous colloidal dispersion at an acid pH lower than about 5.0 but responsive to pH adjustment with base. These emulsion polymers adjusted to a pH of 5.5-10.5 or higher are effective thickeners for a wide variety of aqueous systems including cosmetic products, drilling muds, and particularly aqueous coating compositions such as latex paint.

Continuous emulsion polymerization. Modeling oscillations in vinyl acetate polymerization

Abstract: A theoretical investigation of the emulsion polymerization of vinyl acetate in a continuous stirred tank reactor operating under conditions of sustained oscillations is reported here. Models of two levels of sophistication are developed: a comprehensive model that solves for the age distribution function of polymer particles and a simplified model that assumes discrete nucleation periods. The latter model should find use in adaptive control of latex reactors. These models adequately simulate experimental data after Greene et al.2 for the emulsion polymerization of vinyl acetate under conditions of sustained oscillations.

Hydrophilic polymeric membranes, process for their preparation, their use as ultrafiltration membranes, and precursor membranes adapted to be converted thereto

Abstract: The invention provides a hydrophilic microporous polymeric membrane comprising an intimate blend of a vinylidene fluoride polymer and from 20 to 75% by weight, based on total polymer, of a vinyl alcohol polymer. This membrane may be prepared by casting a thin film of a casting solution comprising a solution of a vinylidene fluoride polymer and from 35 to 85 weight percent, based on total polymer, of a vinyl acetate polymer in a solvent on a support base, partially evaporating the solvent from the cast film, contacting the partially evaporated cast film with a leaching liquid to render the film microporous, and hydrolyzing the vinyl acetate polymer in the leached membrane to convert the acetate groups to hydroxyl groups and provide a membrane having good mechanical strength and hydrophilic properties. The membrane is useful as an ultrafiltration membrane, particularly in the treatment of oil-in-water emulsions or whey. By first forming a film of the vinylidene fluoride polymer and the vinyl acetate polymer, the difficulty previously associated with incorporating a hydrophilic polymer, such as a vinyl alcohol polymer, in a hydrophobic polymer, such as a vinylidene fluoride polymer is obviated.

Aqueous coating composition

Abstract: PURPOSE:An aqueous coating compostion having remarkably improved adhesivity to the surface of a substrate, obtained by blending an emulsion synthetic resin with a specific cyclopentadiene tackifier resin. CONSTITUTION:A) 100 parts by wt. of an emulsion synthetic resin, e.g., acrylic resin, vinyl acetate resin, styrene-butadiene resin, etc., is blended with B) 5-100 parts by wt. of a cyclopentadiene tackifier resin obtained by polymerizing a monomer of cyclopentadiene compound with an ester bond-containing monoolefin monomer in the absebce of a nonradical catalyst in an inert hydrocarbon solvent or without the solvent at 200-300 deg.C for 0.5-20 hours under heating, having a saponification value of 100-200 and a softening point of 70-140 deg.C.

Fibers, yarns and fabrics of low modulus polymer

Abstract: Fibers, yarns and fabrics are produced from polymers, such as the copolymers of ethylene and vinyl acetate, having an elastic modulus of from 5,000 to 60,000 psi. The fibers are also characterized by an area moment of inertia of from 400×10 -14 to 7,000×10 -14 in 4 and a stiffness parameter of from 1×10 -5 to 1×10 -8 lb-in 2 . Multiple fibers are spun into yarn, preferably cross-linked either chemically or by irradiation and are formed into pile fabrics for carpeting and similar uses. The pile fabric preferably has a minimum of 4,000 fibers per in 2 of backing and a minimum pile height of 1/8 inch.

Solvent effect on radical polymerization of vinyl acetate.

Abstract: Absolute rate constants of vinyl acetate (VAC) polymerization have been measured by using the intermittent illumination method in various aromatic solvents and ethyl acetate at 30°. It was shown that the solvent effect was mainly ascribed to the variation in propagation rate constants (kp) with solvents rather than that in termination rate constants (kt). The kp increased in the order: benzonitrile < ethyl benzoate < anisole < chlorobenzene < fluorobenzene < benzene < ethyl acetate. This order is almost the same as that for vinyl benzoate (VBZ) previously reported. There was about an eightyfold difference between the largest and the smallest values. This large variation in kp is explained neither by copolymerization through solvents nor the chain transfer to solvents, but by a reversible complex formation between the propagating radical and aromatic solvents. The kp was determined in mixed solvents of ethyl benzoate and ethyl acetate, decreasing with increasing content of ethyl benzoate. This result supports the idea of a reversible complex. The stability constants (Ks) of the complex were estimated on the assumption that the complexed radical was in a dormant state and inactive in the polymerization. The correlation between Ks or kp and the calculated delocalization stabilization energy for the complex was found, and supported the explanation for the solvent effect.

Powder coating composition composed of ethylene resin mixture and hydrocarbon wax

Abstract: A powder coating composition comprising (A) 70 to 97% by weight of an ethylene resin mixture composed of (A-1) an ethylene copolymer having a melt index of 1 to 50 and containing at least one comonomer selected from the group consisting of alpha-olefins other than ethylene, dienes, vinyl acetate, vinyl alcohol, acrylic acid, functional derivatives of acrylic acid, methacrylic acid and functional derivatives of methacrylic acid, and (A-2) a graft copolymer of polyethylene having grafted thereto an unsaturated carboxylic component, the amount of said unsaturated carboxylic component being 0.001 to 2% based on the weight of the ethylene resin mixture (A), and (B) 3 to 30% by weight of a hydrocarbon wax having a number average molecular weight of about 400 to about 3,000 and a density of not less than 0.9 g/cm 3 , said wax having an acid value of up to about 5 when it is a modified wax.

Process for the use of vinyl acetate-ethylene copolymer emulsions to adhere fibers to carpet backing

Abstract: Use of vinyl acetate-ethylene copolymer emulsions as laminating adhesives for rug backing is disclosed. The copolymer emulsions are prepared by admixing vinyl acetate-ethylene copolymer, dispersant and thickening agent together, with or without the addition of filler. The vinyl acetate-ethylene copolymer can contain between about 20 and about 70 parts by weight of vinyl acetate and between about 30 and about 80 parts by weight of ethylene. The resulting vinyl acetate-ethylene copolymer emulsions have a glass transition temperature (T g ) of between about -35° C. and about -10° C.

Graft polymerization of vinyl acetate onto starch. Saponification to starch–g–poly(vinyl alcohol)

Abstract: at a radiation dose of 1.0 IvIrad. However, over half of the polymer was present as ungrafted poly­ (vinyl acetate) (grafting efficiency less than 50%), and the graft copolymer contained only :34'1,) grafted synthetic polymer (:34% add-on). Lower irradiation doses produced lower conversions of monomer to polymer and gave graft copolymers with lower % add-on. Addition of minor amounts of acryl­ amide, methyl acrylate, and methacrylic acid as comonomers produced only small increases in % add-on and grafting efficiency. However, grafting efficiency was increased to 70% when a monomer mixture containing about 10% methyl methacrylate was used. Grafting efficiency could be increased to over 90% if the graft polymerization of vinyl acetate-methyl methacrylate was carried out near O°C, although conversion of monomers to polymer was low and grafted polymer contained 40-50',\0 poly(methyl methacrylate). Selected graft copolymers were treated with methanolic sodium hy­ droxide to convert starch-g-poly(vinyl acetate) to starch-g-poly(vinyl alcohol). The molecular weight of the poly(vinyl alcohol) moiety \vas about 30,000. The solubility of starch-g-poly(vinyl alcohol) in hot water was less than .50%; however, solubility could be increased by substituting either acid-modified or hypochlorite-oxidized starch for unmodified starch in the graft polymerization reaction. Vinyl acetate was also graft polymerized onto acid-modified starch which had been dis­ persed and partially solubilized by heating in water. A total irradiation dose of either 1.0 or 0.5 Mrad gave starch-g-poly(vinyl acetate) with about :35% add-on, and a grafting efficiency of about 40');, was obtained. A film cast from a starch-g-poly(vinyl alcohol) copolymer in which homopolymer was not removed exhibited a higher ultimate tensile strength than a comparable physical mixture of starch and poly(vinyl alcohol).

Flame retardant compositions

Abstract: The invention concerns a novel cladded elongate substrate such as a jacketed cable, the cladding being flame retarded and comprising a vinyl acetate/alkene copolymer composition incorporating a halogen-free inorganic flame retardant. The composition is characterized by a high content of vinyl acetate and/or the presence of a polyalkene or alkene/alkene copolymer blended with the vinyl acetate/alkene copolymer.

Microporous polymeric membrane

Abstract: A microporous polymeric membrane is made by preparing a polymer-casting solution, casting a thin film of the casting solution on a support base, allowing partial evaporation of the solvent from the cast film for a predetermined period of time and contacting the partially evaporated film with a leaching liquid to provide the microporous membrane. A membrane with particularly good mechanical strength and hydrophilic properties is formed when the casting solution comprises a vinylidene fluoride polymer and from about 35 to about 85% by weight of a vinyl acetate polymer; and when the acetate polymer is hydrolyzed after the leaching step to convert the acetate groups to hydroxyl groups.

Binders for paints

Abstract: Binders which comprise (A) an aqueous emulsion of a copolymer A, having a glass transition temperature of 0-50° C., of monoolefinically unsaturated carboxylic acid esters, with or without styrene, vinyl acetate, vinyl chloride and acrylonitrile, which copolymer contains, as copolymerized units, small amounts of monoolefinically unsaturated monocarboxylic acids and/or dicarboxylic acids and/or their amides (of which the nitrogen atoms may or may not be alkyl-substituted and/or alkylol-substituted) and small amounts of monomers containing carbonyl groups, (B) from 0.05 to 1 mole, per mole of carbonyl groups present in the copolymer A, of a water-soluble aliphatic dihydrazine compound and (C) from 0 to 0.02 mole, per mole of dihydrazine compound, of a water-soluble zinc, manganese, cobalt and/or lead salt, or particularly suitable for use in paints and pebble dash renderings, since they give films which adhere particularly well to alkyd resin primers and which show particularly little tendency to whitening.

Thermoplastic mixtures of polypropylene with ethylene/vinyl acetate and ethylene/propylene copolymers

Abstract: A thermoplastic mixture comprising (A) from 2 to 40% by weight of a partially crystalline ethylene/propylene copolymer or terpolymer having an ethylene content of from 70 to 90% by weight and an endothermic heat of fusion of from 6 to 18 cal/g, (B) from 30 to 93% by weight of a crystalline polypropylene, and (C) from 5 to 30% by weight of a copolymer of ethylene and vinyl acetate containing from 20 to 70% by weight of vinyl acetate, the percentages being based on the sum of (A)+(B)+(C).

Aqueous polymeric dispersions, paper coating compositions and coated paper articles made therewith

Abstract: Lightweight coated paper articles having a desirable combination of properties are obtained through the use of coating compositions employing as the binder component thereof certain novel polymeric dispersions which comprise a major proportion on a dry basis of an alkali insoluble polymer and a minor proportion (e.g., from about 0.5 to about 25 weight percent on a dry basis based upon the alkali insoluble polymer) of certain alkali soluble polymers. Exemplary of the alkali insoluble polymers employed herein are both the carboxylated and noncarboxylated versions of known addition polymerized synthetic polymers having a glass transition temperature of about 50° C. or less. Exemplary of the alkali soluble polymers employed herein are synthetic addition polymers comprising (in polymerized form and in weight percent based on such polymer) from about 40 to about 90 percent of a vinyl ester of a carboxylic acid (e.g., vinyl acetate, vinyl propionate, etc.); from about 5 to about 55 percent of the nitrile or a C 1 -C 8 alkyl ester of a monoethylenically unsaturated carboxylic acid; and from about 5 to about 15 percent of a monoethylenically unsaturated carboxylic acid.

Thermal decomposition of ozonides. A complementary method to the Baeyer–Villiger oxidation of hindered ketones

Abstract: Treatment of vinyl acetate with ozone yields the mixed anhydride of acetic and formic acids and formaldehyde oxide. The formaldehyde oxide can be trapped by reaction with ketones yielding the corre...

Grafting onto wool. VI. Effect of amines in ceric ion-initiated grafting of poly(vinyl acetate)

Abstract: Poly(vinyl acetate) has been graft copolymerized onto Himachali wool in the presence of ceric ammonium nitrate alone and in presence of amines in aqueous medium under a wide variety of reaction conditions. Nitric acid was found to catalyze the graft copolymerization. Maximum grafting under optimum conditions has been determined. Several grafting experiments were carried out in presence of triethylamine and triethanolamine. Both amines were found to reduce the extent of grafting. The decrease in the percent grafting in presence of amines has been explained in terms of a chain-transfer mechanism.

Kinetics of the emulsion polymerization of vinyl acetate

Abstract: Recent investigations of the emulsion polymerization of vinyl acetate report a variable behavior. The reaction has been reported to exhibit a half-order rate dependence and no particle number dependence on the initiator level, or a first-order dependence for both the reaction rate and particle number on the initiator concentration, or some behavior between these two extremes. While two recent models have attempted to account for the changes in the reaction rate dependence by postulating either an aqueous phase or a polymer phase termination, no adequate explanation of the particle number behavior has been given, nor has a single model been suggested that agrees with all of the experimental data. This investigation confirms the results of previous investigators and develops an empirical model for the particle number, taking into account the effects of the initiator level, emulsifier level and alkyl chain length, temperature, and ionic strength on the particle number. This particle number model, used with a polymer phase termination reaction model, yields a polymerization rate expression which agrees with all previous data.

Sausage casing formed from regenerated cellulose with an internal vinyl acetate coating

Abstract: Sausage casings formed from regenerated cellulose are coated on their internal surfaces with a thin layer of a vinyl acetate polymer which is effective in causing the casing to adhere to a sausage emulsion and follow the shrinkage of the sausage during curing.

Support catalyst for the preparation of vinyl acetate from ethylene, acetic acid and oxygen in the gaseous phase.

Abstract: The carriers contain common active components, namely noble metals of the 8th sub-group or compounds thereof, and as activators alkali metal compounds, alkaline earth metal compounds or cadmium compounds. The carriers, too, consist of common materials, such as silicic acid. A novel feature is to be seen in the shape of the carrier particles which are designed as rod sections having a star-shaped cross section (FIGS. 1 to 7) or as ribbed rods (FIG. 8). In relation to the apparent density and thus in relation to the amount of noble metal employed, a considerably higher space-time yield is reached than with carrier particles of a conventional shape.

Molecular architecture and physicochemical properties of some vinyl alcohol‐vinyl acetate copolymers

Abstract: Two series of vinyl alcohol-vinyl acetate copolymers were prepared by homogeneous and heterogeneous acetylation of the same precursor poly(vinyl alcohol). Their intramolecular monomer distributions were analyzed by IR spectrometry, calorimetry, and differential thermal analysis. The results show a more blocky distribution for the heterogeneously prepared copolymers. The properties of these (co)polymers in dilute aqueous solution were determined by means of viscometry. Whereas the copolymer-solvent interaction parameter of the homogeneously acetylated, random copolymers hardly varied with acetate content, a definite minimum was found for the blocky copolymers at about 7 mole% vinyl acetate. These findings were attributed to the incompatibility of dissimilar sequences, which sharply decreases with decreasing vinyl acetate sequence length. Up to about 17 mole% vinyl acetate content, the solvent quality for the copolymers is at least as good as for poly(vinyl alcohol). In addition, the dilute solution properties of the samples were established in water saturated with 1-butanol. For copolymers with up to about 17 mole% vinyl acetate, at 25°C this mixture is a better solvent than water. The highest increase in solvent quality was found for the homopolymer, whereas the increase diminished with acetate content, irrespective of the intramolecular vinyl acetate distribution. These findings are explained in terms of preferential adsorption of 1-butanol onto the (co)polymer backbone due to hydrophobic interactions and prevention of this process by the bulky acetate groups.

Alternating and Random Copolymers of Vinyl Acetate and Maleic Anhydride

Abstract: Alternating copolymers of vinyl acetate (VAc) and maleic anhydride (MA) are produced preferentially when VAc and MA are copolymerized at moderate temperatures while random copolymers are produced at temperatures above 90°C. A charge-transfer complex (CTC) of VAc/MA exists at moderate temperatures but does not exist at temperatures above 90°C.

Heat fusible poly(vinyl acetate) dispersions

Abstract: It has been discovered that pastes of particulate, thermoplastic, poly(vinyl acetate) type polymers dispersed in a soft resinous phase can be prepared which heat-set by fusion of the thermoplastic binder. When pigmented or otherwise colored, these formulations have utility as printing inks. When uncolored, they can be used as clear overprint coatings. In addition, these fusible pastes have utility as specialty coatings in adhesives and can be fabricated into self-supporting shapes.

Smooth-look footwear composition

Abstract: A non-delaminating polymeric composition having a smooth appearance along with improved solvent resistance comprises a mixture of particular linear and radial monoalkenyl arene-diene block copolymers, a low density polyethylene, ethylene/vinyl acetate copolymer, hydrocarbon extending oil and filler. The block copolymers, polyethylene and ethylene/vinyl acetate copolymer are selected such that essentially isoviscous melt blending conditions are attained.

Viscosity of poly(vinyl acetate) and its concentrated solutions

Abstract: Data on the viscosity of poly(vinyl acetate) (PVOAc) and its concentrated solutions in diethyl phthalate (DEP) and cetyl alcohol (CeOH) are examined over the molecular weight range 8 × 103 ca. 0.25, increasing with decreasing φ for smaller φ. Both β and T0 depend on φ, and T0 also depends on M at low M.

Decomposition of peroxide on carboxymethyl cellulose and its ability to initiate graft copolymerization

Abstract: The decomposition of the peroxide group on fibrous carboxymethyl cellulose (CMC) and its ability to initiate graft copolymerization were investigated. The peroxide on CMC liberated hydrogen peroxide when the sample was heated in an aqueous medium. The decomposition of the peroxide was markedly increased by the use of ferrous salt and the irradiation with light of λ > 300 nm. The grafting of methyl methacrylate on CMC peroxide was initiated by heating or irradiating with light, where the rate of grafting and the reciprocal of the average molecular weight of grafts in general were proportional to the square root of the peroxide content of the sample. The peroxide content of the sample was related closely to the number of grafts in initiation. The number was estimated as 17 times for thermal initiation and 6 times for photoinitiation at the maximum values. The CMC peroxide showed a marked activity toward photografting of acrylamide, acrylic acid, acrylonitrile, and vinyl acetate on the substrate.