Showing papers on "Vinyl acetate published in 1997"

Handbook of Engineering Polymeric Materials

Abstract: Artificial neural networks as a semi-empirical modelling tool for physical property predictions in polymer science new generation high performance polymers by displacement polymerization acrylamide polymers transparent polyolefins the polyolefins stabilizers with intramolecular synergism high-temperature stabilization of polyolefins poly(malic acid) from natural sources stabilization of polyolefins gamma radiation induced preparation of polyelectrolytes and its use for treatment of waste water polyvinylchloride (PVC)/thermoplastic polyurethane (TPU) polymeric blends mechanical properties of ionomers and ionomer blends metallocene based polyolefins - product characteristics preparations and properties of porous poly(vinyl alcohol)-poly(vinyl acetate) composites hydrophobization of polyanionic polymers to achieve higher biological activity uniform latex particles reaction mechanism of vinyl polymerization with amine in redox and photo-induced charge-transfer initiation systems photoinitiation of free-radical polymerization by organometallic compounds chemical modification of polystyrenes in the presence of cationic catalysis and their industrial applications performance of polyethylenes in relation to their molecular structure the crystallization of polyethylene under high pressure structure, stability, and degradation of PVC solution state of metal complex calixarenes and polymetric calixarenes thermodynamic opportunity of degradation reaction initiation polymerization by ylides. (Part contents).

High solids vinyl acetate-ethylene emulsions

Abstract: A vinyl acetate-ethylene copolymer emulsion having a solids content of at least 65 percent by weight is disclosed. Specifically, the copolymer emulsion comprises about 5 to 40 percent by weight ethylene, about 60 to 95 percent by weight vinyl acetate, about 0.8 to 2.0 percent by weight of a fully or partially hydrolyzed polyvinyl alcohol, and a mixture of nonionic ethoxylated alkyl phenol surfactants having a HLB of from about 16.0 to 16.5.

Biocatalytic plastics as active and stable materials for biotransformations.

Abstract: Enzyme-containing polymeric materials have been developed that have high activity and stability in both aqueous and organic media. These biocatalytic plastics, containing alpha-chymotrypsin and subtilisin Carlsberg, can contain up to 50% (w/w) total protein in plastic materials such as poly(methyl methacrylate, styrene, vinyl acetate, and ethyl vinyl ether). The activation achieved in organic solvents by incorporating proteases in plastic matrices allows for the efficient synthesis of peptides, and sugar and nucleoside esters. The marriage of enzyme technology with polymer chemistry opens up an array of unique applications for plastic enzymes, including active and stable biocatalysts in paints, coatings, resins, foams, and beads, as well as membranes, fibers, and tubings.

Integrated process for the production of vinyl acetate and/or acetic acid

Abstract: Acetic acid and/or vinyl acetate are produced by an integrated process which comprises the steps: (a) contacting in a first reaction zone a gaseous feedstock comprising ethylene and/or ethane and optionally steam with a molecular oxygen-containing gas in the presence of a catalyst active for the oxidation of ethylene to acetic acid and/or ethane to acetic acid and ethylene to produce a first product stream comprising acetic acid, water and ethylene (either as unreacted ethylene and/or as co-produced ethylene) and optionally also ethane, carbon monoxide, carbon dioxide and/or nitrogen; (b) contacting in a second reaction zone in the presence or absence of additional ethylene and/or acetic acid at least a portion of the first gaseous product stream comprising at least acetic acid and ethylene and optionally also one or more of water, ethane, carbon monoxide, carbon dioxide and/or nitrogen with a molecular oxygen-containing gas in the presence of a catalyst active for the production of vinyl acetate to produce a second product stream comprising vinyl acetate, water, acetic acid and optionally ethylene; (c) separating the product stream from step (b) by distillation into an overhead azeotrope fraction comprising vinyl acetate and water and a base fraction comprising acetic acid; (d) either (i) recovering acetic acid from the base fraction separated in step (c) and optionally recycling the azeotrope fraction separated in step (c) after partial or complete separation of the water therefrom to step (c), or (ii) recovering vinyl acetate from the azeotrope fraction separated in step (c) and optionally recycling the base fraction separated in step (c) to step (b), or (iii) recovering acetic acid from the base fraction separated in step (c) and recovering vinyl acetate from the overhead azeotrope fraction recovered in step (c).

On‐line control of a semibatch emulsion polymerization reactor based on calorimetry

Abstract: In this work, on-line calorimetry was used to estimate the conversion and the copolymer composition in emulsion polymerization systems. Real-time feedback control of the polymer composition during the semibatch emulsion copolymerization of vinyl acetate and butyl acrylate was carried out. Both homogeneous copolymers and copolymers with previous defined composition profiles were obtained. It was shown that the feedback control was able to avoid monomer accumulation in the reactor, and hence potentially dangerous thermal runaways, without any deleterious effect on the polymer composition, when a sudden inhibition was caused by deliberately adding a solution of hydroquinone. The use of feedback control for the maximization of the production rate under safe conditions in the unseeded emulsion copolymerization of vinyl acetate and VeoVa10 (an alkyl vinyl ester from Shell) is also presented.

Reactive Surfactants in Heterophase Polymerization. 9.† Optimum Surfmer Behavior in Emulsion Polymerization

Abstract: In an attempt to define the conditions for the optimum use of polymerizable surfactants (surfmers), two anionic maleate surfmers were applied in various emulsion copolymerization systems including styrene/butyl acrylate/acrylic acid, vinyl acetate/VEOVA 10/acrylic acid, vinyl acetate/butyl acrylate/acrylic acid, and methyl methacrylate/butyl acrylate/vinyl acetate. It was found that the reactivity ratios were the most important variable controlling the incorporation of the surfmer into the polymer chains. The surfmer conversion also depended on the particle size: the larger the particle size, the lower the surfmer conversion. It was also found that when the surfmer copolymerized well with the monomers attaining high conversions from the beginning of the process onward, a significant part of the surfmer was buried in the particle interior, leading to unstable latexes. On the basis of the results, an optimum surfmer behavior was defined. Some preferable combinations of surfmer reactive groups and comonomer...

Short-Chain Branching Structures in Ethylene Copolymers Prepared by High-Pressure Free-Radical Polymerization: An NMR Analysis

Abstract: It is well-known that short-chain branching (SCB) reactions (intramolecular H-abstraction) play an important role in determining the properties of ethylene homopolymers produced under high pressure by free-radical polymerization. There is little information, however, regarding SCB mechanisms that occur during the synthesis of ethylene copolymers under similar reaction conditions. This work describes SCB structures for a wide range of ethylene copolymers of varying composition (ethylene with n-butyl acrylate (nBA), methyl acrylate (MA), vinyl acetate (VAc), n-butyl methacrylate (nBMA), acrylic acid (AA), and methacrylic acid (MAA)), as determined by proton, 13C, and 2D NMR techniques. Close examination of the resonances reveals that for many (if not all) of these copolymers, a significant fraction of the SCBs contain comonomer as a result of CH2-radical to CH2 backbiting around a comonomer unit. In addition, SCBs are formed not only by hydrogen abstraction from CH2 polyethylene units but also by abstractio...

Functional Group Accessibility in Hydrogen-Bonded Polymer Blends. 2. Miscibility Map of 2,3-Dimethylbutadiene- stat-vinylphenol Blends with Ethylene-stat-vinyl acetate

Abstract: An experimental miscibility map for 2,3-dimethylbutadiene-stat-4-vinylphenol (DMBVPh) blends with ethylene-stat-vinyl acetate (EVA) is obtained and compared to theoretical calculations. The number of hydrogen-bonded carbonyl groups in these systems is measured by FTIR spectroscopy and some systematic trends are apparent. It is shown that the miscibility of DMBVPh/EVA blends is much more sensitive to the difference in solubility parameters than to the degree of hydrogen bonding. However, the contribution from hydrogen bonding in these mixtures is important and is significantly influenced by screening effects. A simple correlation for the dependence of the screening effect on the average spacing of functional groups in a chain is proposed and tested.

A two step gold addition method for preparing a vinyl acetate catalyst

Abstract: A method for preparing a catalyst wherein a catalytic carrier is impregnated with water-soluble palladium and gold compounds followed by fixing and then reducing the fixed palladium and gold compounds to palladium and gold metal followed by impregnating the carrier with a second amount of a water-soluble gold compound. The second amount of gold compound is fixed, then reduced to gold metal. The catalyst then is impregnated with an alkali metal acetate such as potassium acetate. The catalyst can be employed to synthesize unsaturated esters such as vinyl acetate.

The Gas Phase Reaction of Unsaturated Oxygenates with Ozone: Carbonyl Products and Comparison with the Alkene-Ozone Reaction

Abstract: Carbonyl products have been identified and their formation yields measured in the gas phase reaction of ozone with unsaturated oxygenates in experiments carried out at ambient T, p = 1 atm. of purified humid air (RH = 50%) and with sufficient cyclohexane added to scavenge the hydroxyl radical. The compounds studied are the esters methyl acrylate, vinyl acetate and cis-3-hexenyl acetate, the carbonyl crotonaldehyde, the hydroxy-substituted diene linalool, the ether ethylvinyl ether and the keto-ether trans-4-methoxy-3-buten-2-one. The alkene 1-pentene was included for comparison. The nature and formation yields of the carbonyl products from this study and those measured in earlier work under the same conditions are compared to those of alkenes and are supportive of a reaction mechanism that is similar to that for the reaction of ozone with alkenes, i.e. O3 + R1R2C=CR3X → α(R1COR2 + R3XCOO) + (1 − α)(R3COX + R1R2COO), where Ri are the alkyl substituents, X is the oxygen-containing substituent (–CHO for aldehydes; –C(O)R for ketones; –C(O)OR and –OC(O)R for esters; –OH and hydroxyalkyl for alcohols; and –OR for ethers), R1COR2 is the primary carbonyl, R3COX is the other primary product and R1R2COO and R3XCOO are the carbonyl oxide biradicals. The biradicals lead to carbonyls in reactions that are also analogous to those involved in carbonyl formation from biradicals in the ozone-alkene reaction. These features make it possible to predict the nature and formation yields of the major carbonyl products of the reaction of ozone with unsaturated oxygenates that may be components of biogenic emissions.

Preparation of syndiotacticity‐rich high molecular weight poly(vinyl alcohol) microfibrillar fiber by photoinitiated bulk polymerization and saponification

Abstract: Vinyl pivalate (VPi) was polymerized in bulk by ultraviolet-ray initiation at low temperatures using 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN) and 2,2'-azobis(isobutyronitrile) (AIBN) as photoinitiators. High molecular weight (HMW) poly(vinyl pivalate) (PVPi), having a number-average degree of polymerization (P n ) of 13,000-28,000, was obtained at conversions below 30% and converted by saponification to a syndiotacticity-rich HMW poly(vinyl alcohol) (PVA) microfibrillar fiber with P n of 7300-18,300, syndiotactic diad (S-diad) and triad contents of ∼ 64% and ∼39%, respectively, and crystal melting temperature (T m ) of ∼249°C. ADMVN gave higher P n than AIBN. On the other hand, conversion was smaller with the former than with the latter, and it was found that the initiation rate of ADMVN was lower than that of AIBN. P n of PVA was constant while P n of the precursor PVPi increased with increasing conversion. The syndiotacticity, T m and thermal stability of PVA obtained from PVPi were much superior to those of PVA derived from poly(vinyl acetate) prepared under the same polymerization conditions. Polymerization of VPi at lower temperatures gave PVA with higher syndiotacticity.

Physical ageing in poly(vinyl acetate) 1. Enthalpy relaxation

Abstract: The enthalpy changes ΔH∞ between a poly(vinyl acetate) glass formed by rapid cooling and the corresponding fully relaxed glass have been estimated at four temperatures below the glass transition. The values obtained were different to those expected by extrapolating liquid behavior below the glass transition and were found to agree well with the predictions of a simple expression for the combined main chain conformational and free volume contributions to enthalpy. Conformational contributions from the side chain alone were also considered but were not required to obtain agreement with experiment. It can be concluded that the side chains remained mobile below the glass transition and do not contribute to the heat capacity discontinuity at T g .

Palladium, gold and boron catalyst and process for the preparation of vinyl acetate

Abstract: A catalyst for preparing vinyl acetate in the gas phase from ethylene, acetic acid and oxygen or oxygen-containing gases with, at the same time, low-high boiler formation which catalyst comprises palladium and/or its compounds, gold and/or its compounds, moron or boron compounds and alkali metal compounds on a particular support.

A novel water-soluble rhodium-poly(enolate-co-vinyl alcohol-co-vinyl acetate) catalyst for the hydroformylation of olefins

Abstract: The water-soluble polymer, poly(enolate-co-vinyl alcohol-co-vinyl acetate) (PEVV), prepared by controlled oxidation of poly(vinyl alcohol-co-vinyl acetate), is a valuable ligand for the rhodium biphasic catalytic hydroformylation of olefins. The average turnover frequency for the catalytic hydroformylation of 1-octene was 5.46 × 10-5 kmol (kg(Rh)s)-1 at 90 °C, and that of 1-dodecene was 2.36 × 10-4 kmol (kg(Rh) s)-1 at 60 °C. Selective hydroformylation of styrene and its derivatives gave up to 97% of branched-chain aldehyde using Rh−PEVV under biphasic reaction conditions but at low conversions.

Heterogeneous bimetallic palladium-gold catalyst for vinyl acetate production

Abstract: This invention provides a heterogeneous bimetallic palladium-gold catalyst for vinyl acetate production from ethylene, acetic acid and oxygen. An invention catalyst is prepared by forming a first shell dispersion coating of colloidal palladium on the catalyst support surface, and super-imposing a second shell dispersion coating of colloidal gold metal on the catalyst support surface. An organometallic gold compound is employed to apply the gold dispersion on the catalyst support surface. The organometallic gold compound does not require a fixing procedure. A preferred invention palladium-gold catalyst has a high gold metal retention, and exhibits durability and long term selectivity in vinyl acetate production.

Thermal transfer recording medium

Abstract: A thermal transfer recording medium with which an image is transferred excellently even to an object medium, such as durable plastic film, and printed matter having a sufficiently high mechanical friction resistance, a resistance to various solvents and a resistance to light, such as ultraviolet rays is obtained. This thermal transfer medium has at least a support member, and a thermal transfer ink layer provided on this support member. The thermal transfer ink layer contains a coloring agent, and a vinyl chloride copolymer prepared by copolymerizing three components, 50-90 wt.% of vinyl chloride, 5-20 wt.% of vinyl acetate and 10-30 wt.% of hydroxy acrylate, based on the total amount of monomers.

Conducting polymer composites: Polypyrrole and poly(vinyl chloride‐vinyl acetate) copolymer

Abstract: Composites of a polypyrrole (PPy) and poly(vinyl chloride-vinyl acetate) copolymer (PVC-PVA) were prepared both chemically and electrochemically. An insulating polymer was retained in the blend and the thermal stability of the polymer was enhanced by polymerizing pyrrole into the host matrix in both cases. The composites prepared electrochemically gave the best results in terms of conductivity and air stability. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 667–671, 1997

Casting solvent effect on crystallization behavior of poly(vinyl acetate)/poly(ethylene oxide) blends: DSC study

Abstract: Poly(vinyl acetate) (PVAc)/poly(ethylene oxide) (PEO) blends were prepared by casting from either benzene or chloroform. The solvent effects on the crystallization behavior and thermodynamic properties of the blends were studied by the differential scanning calorimeter (DSC). Two grades of PEO with different molecular weights (PEO200 with Mw = 200,000 g/mol and PEO2 with Mn = 2000 g/mol) were used in this work. The thermal analysis revealed that the blends cast from either benzene or chloroform were miscible in the molten state. The crystallization of PEO in the benzene-cast blends was more easily suppressed than it was in the chloroform-cast blends. Furthermore, the benzene-cast blends showed a greater negative value of Flory-Huggins interaction parameter than those cast from chloroform in the PVAc/PEO200 poly-blend system. It was supposed that the benzene-cast blends had more homogeneous morphology. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 411–421, 1997

Vinyl 4-tetrahydropyranyloxybenzal-vinyl 4-hydroxybenzal-vinyl tetrahydropyranyl ether-vinyl acetate copolymer, vinyl 4-tetrahydropyranyloxybenzal-vinyl tetrahydropyranyl ether-vinyl acetate copolymer and preparation methods thereof

Abstract: A vinyl 4-tetrahydropyranyloxybenzal-vinyl 4-hydroxybenzal-vinyl tetrahydropyranyl ether-vinyl acetate copolymer, a vinyl 4-tetrahydropyranyloxybenzal-vinyl tetrahydropyranyl ether-vinyl acetate copolymer and a preparation method thereof are provided. The copolymers have excellent transparency because they are very low in optical absorbance in the deep uv range. In addition, the acetal structure in the backbone and in the substituted groups endows the photoresist of the copolymer with superior dry etch resistance.

Preparation of vinyl acetate

Abstract: This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

Synthesis and Biocompatibility of Maleic Anhydride Copolymers: 1. Maleic Anhydride–Vinyl Acetate, Maleic Anhydride–Methyl Methacrylate and Maleic Anhydride–Styrene†

Abstract: A series of maleic anhydride (MA)-vinyl acetate (VA), MA-methyl methacrylate (MM) and MA-styrene (S) copolymers were prepared and characterized. By employing various amounts of initiator, MA-VA, MA-MM and MA-S copolymers with molecular weights ranging between 18000 and 219000 were obtained. The 'in vivo' and'in vitro' tests performed on K562 cellular cultures (human chronic myeloid leukaemia) and also on Westar rats (inoculated with the Walker 256 carcinosarcome) showed that, as a function of the molecular weight, the copolymers synthesized had a 50% in vitro cytotoxicity and a mean tumour regression of a maximum of 68%.

Peel adhesion and viscoelasticity of poly(ethylene‐co‐vinyl acetate)‐based hot melt adhesives. I. The effect of tackifier compatibility

Abstract: A series of poly(ethylene-co-vinyl acetate) (EVA)-based hot melt adhesives containing either a rosin or a hydrocarbon (C5–C9) tackifier have been prepared to investigate viscoelastic properties and peel adhesion. Fracture energies were determined by the use of a T-Peel geometry (two polypropylene films bonded with model EVA adhesives). The rosin has only one glass transition temperature, but the C5–C9 resin has two glass transition temperatures, indicating phase separation. The rosin has better compatibility with EVA than does the C5–C9 resin. The bond strength of tackified EVA to polypropylene depends not only on compatibility, but also on viscoelastic properties. A higher storage modulus results in a higher T-Peel strength. Under certain test conditions, glassy C5–C9-rich domains act as reinforcing filler, resulting in a higher storage modulus. Here, a C5–C9-tackified EVA adhesive has higher T-Peel strength than does one containing rosin. © 1997 John Wiley & Sons, Inc.

A method of killing or inhibiting microbial cells

Abstract: A method of killing or inhibiting the growth of microbial cells present on laundry, hard surfaces, human or animal skin, mucous membranes, teeth, wounds, bruises or in the eye, comprising contacting the cells with a composition comprising a poly-cationic compound, preferably a polyamino acid, a polyvinylamine, a copolymer prepared from vinylamine and one or more carboxylic acid anhydrides, e.g. a polymer comprising 0.1-100 mol% vinyl amine or ethyleneimine units, 0-99.9 mol% units of at least one monomer selected from N-vinylcarboxamides of formula (I) wherein R?1 and R2? are hydrogen or C?1?-C6-alkyl; vinyl formate, vinyl acetate, vinyl propionate, vinyl alcohol, C1-C6-alkyl vinyl ether, mono ethylenic unsaturated C3-C8-carboxylic acid, and esters, nitriles, amides and anhydrides thereof, N-vinylurea, N-imidazoles and N-vinyl imidazolines; and 0-5 mol% units of monomers having at least two unsaturated ethylenic double bonds; and one or more enzymes, preferably glycanases, muranases, oxidoreductases, glucanases, proteases, cellulases, amylases, lipases, pectinases and xylanases.

Process for the preparation of vinyl acetate

Abstract: This invention pertains to the preparation of vinyl acetate by contacting within a contact zone a mixture of ketene and acetaldehyde with an acid catalyst at one bar (100 kPa) pressure and between 85 and 200 ~C and removing the reaction products from the contact zone.

Palladium-gold catalyst vinyl acetate production

Abstract: This invention provides a supported palladium-gold catalyst for vinyl acetate production from ethylene, acetic acid and oxygen. The reactants employed in the catalyst preparation are potassium salt compounds which are essentially sodium-free. A preferred invention palladium-gold catalyst provides exceptional improvement of carbon dioxide selectivity in vinyl acetate production.