Showing papers on "Vinyl acetate published in 1995"

Standard Pressure Volume Temperature Data for Polymers

Abstract: 1. INTRODUCTION Pressure-Volume-Temperature (PVT) Data: Equilibrium and Nonequilibrium States of Polymers Scope of This Data Collection Equipment for PVT Measurements: Piston-Die Technique Confining Fluid Technique Equipment Used for Data in This Book Experimental Procedures: Stan- dard PVT Runs Sample Preparation Determination of the Specific Volume at Ambient Conditions Data Interpretation: Tables and Graphs in This Collection Liquids Materials Undergoing a Glass Transition Materials Having a Melt Transition Filled Materials and Blends Application of PVT Data Empirical and Theoretical Fits to PVT Data References 2. HYDROCARBONS n-Undecane (C11H24) n-Tetradecane (C14H30) n-Hexadecane (C16H34) n-Tetracosane (C24H50) n-Hexatriacotane (C36H74) n-Tetratetracotane (C44H90) 3. HYDROCARBON POLYMERS Polyethylene (linear) Polyethylene (branched) Polyethylene wax (M ~2100) Polyethylene wax (M ~1000) Poly(propylene) (atactic) Polypropylene (atactic) Polypropylene (isotactic) Poly(1-butene) (atactic) Poly(1-butene) (isotactic) Poly(1-octene) Polyisobutylene (M ~ 4.2 x 105) Polyisobutylene (M ~ 300) Polyisoprene (hydrogenated) Poly(4-methyl pentene-1) Polynorbornene Hydrocarbon resin Poly(ethylene-co-propylene) (23% polypropylene) Poly(ethylene-co-propylene) (57% propylene) Poly(ethylene-co-propylene) (76% propylene) Poly(ethylene-co-propylene) (84% propylene) Polybutadiene (M ~ 2.33 x 105) Polybutadiene (cis & trans) Polybutadiene (cis) Polybutadiene (M ~ 3000) Polybutadiene (M ~ 1000) Natural rubber 4. ETHYLENE POLYMERS crylic acid) Poly(ethylene-co-methacrylic acid) (9% methacrylic acid) Poly(ethylene-co-methacrylic acid) (11.5% methacrylic acid) Poly(ethylene-co-methacrylic acid) (12% methacrylic acid) Poly(ethylene-co-methacrylic acid) (15% methacrylic acid) Poly(ethylene-co-methacrylic acid) (20% methacrylic acid) Ionomer (~ 1.5% Na) Ionomer (~ 2.2% Na) Poly(ethylene-co-acrylic acid) (9% acrylic acid) Poly(ethylene-co-acrylic acid) (10% acrylic acid) Poly(ethylene-co-acrylic acid) (20% acrylic acid) Poly(ethylene-co-vinyl alcohol) (56% vinyl alcohol) Poly(ethylene-co-vinyl alcohol) (62% vinyl alcohol) Poly(ethylene-co-vinyl alcohol) (70% vinyl alcohol) 5. STYRENICS Polystyrene (M ~ 1.1 x 105) Polystyrene (M ~ 34500) Polystyrene (M ~ 9000) Polystyrene (M ~ 910) Poly(4-chloro styrene) Poly(styrene-block-hydrogenated butadiene) 6. ACRYLICS Poly(methyl methacrylate) (M ~ 1 x 105) Poly(methyl methacrylate) (M ~ 40000) Poly(methyl methacrylate) (M ~ 25000) Poly(methyl methacrylate) (M ~ 10000) Poly(ethyl methacrylate) Poly(propyl methacrylate) Poly(n-propyl methacrylate) Poly(n-butyl methacrylate) Poly(n-hexyl methacrylate) Poly(lauryl methacrylate) Poly(isobutyl methacrylate) Poly(methyl acrylate) Poly(ethyl acrylate) Poly(n-propyl acrylate) Poly(n-butyl acrylate) Poly(acrylic acid) Poly(methacrylic acid) 7. POLYACRYLONITRILE AND COPOLYMERS Polyacrylonitrile Poly(styrene-co-acrylonitrile) (25% acrylonitrile) Poly(acrylonitrile-co-butadiene) (67% butadiene) Nitrile rubber compound 8. OTHER C-C MAIN CHAIN POLYMERS Poly(vinyl acetate) Poly(vinyl alcohol) Poly(vinyl butyral) Poly(vinyl carbazole) Poly(vinyl chloride) Poly(vinyl fluoride) Poly(vinyl formal) Poly(vinylidene fluoride) Poly(tetrafluoro ethylene) Fluoropolymer glass Fluoroelastomer compound Perfluoroelastomer compound 9. POLYETHERS Poly(methylene oxide) (homopolymer) Poly(methylene oxide) (copolymer) Poly(ethylene oxide) (M x105) Poly(ethylene oxide) (M ~ 18500) Poly(ethylene oxide) (M ~ 1540) Poly(ethylene oxide) (M ~ 600) Poly(ethylene oxide) (M ~ 300) Poly(ethylene oxide) mono methyl ether (M ~ 750) Poly(ethylene oxide) mono methyl ether (M ~ 350) Poly(ethylene oxide) dimethyl ether (M ~ 1000) Poly(ethylene oxide) dimethyl ether (M ~ 600) Poly(propylene oxide) (M ~ 4000) Poly(propylene oxide) (M ~ 2000) Poly(propylene oxide) (M ~ 1025) Poly(propylene oxide) (M ~ 400) Poly(propylene oxide) dimethyl ether (M ~ 2000) Poly(propylene oxide) dimethyl ether (M ~ 1025) Poly(propylene oxide) dimethyl ether (M ~ 400) Poly(hexafluoropropylene oxide) (M ~ 7000) Poly(hexafluoropropylene oxide) (M ~ 2000) Silicone fluid (commercial) Poly(dimethyl siloxane) (M ~ 1.5 x 106) Poly(dimethyl siloxane) (M ~ 2.24 x 105) Poly(dimethyl siloxane) (M ~ 17200) Poly(dimethyl siloxane) (M ~ 9670) Poly(dimethyl siloxane) (M ~ 3900) Poly(dimethyl siloxane) (M ~ 870) Poly(dimethyl siloxane) (M ~ 340) 10. POLYAMIDES Nylon 6 Nylon 7 Nylon 9 Nylon 11 Nylon 12 Nylon 4/6 Nylon 6/6 Nylon 6/6 (rubber toughened) Nylon 6/7 Nylon 6/8 Nylon 6/9 Nylon 6/10 Nylon 6/10 (pure) Nylon 6/12 Nylon 13/13 Nylon 6I/6T Aramid fiber 11. POLYESTERS Poly(ethylene adipate) Poly(ethylene succinate) Polycaprolactone Poly-L-lactide Poly(ethylene isophthalate) Poly(ethylene terephthalate) Poly(ethylene naphthenoate) Poly(butylene terephthalate) Bisphenol A isophthalate Polyarylate 12. VARIOUS MAIN CHAIN AROMATICS Polycarbonate Chloral polycarbonate Poly(2-6-dimethyl phenylene oxide) Phenoxy resin Polyetherimide Polyimide (film) Poly(ether ether ketone) Poly(ether sulphone) Polysulfone Poly(azomethine ether) (n = 4) Poly(azomethine ether) (n= 7) Poly(azomethine ether) (n= 8) Poly(azomethine ether) (n= 9) Poly(azomethine ether) (n= 10)Poly(azomethine ether) (n= 11) 13. BLENDS Polystyrenepoly(vinyl methyl ether) blend (90/10) Polystyrenepoly(vinyl methyl ether) blend (80/20) Polystyrenepoly(vinyl methyl ether) blend (70/30) Polystyrenepoly(vinyl methyl ether) blend (60/40) Poly- styrenepoly(vinyl methyl ether) blend (50/50) Polystyrenepoly(vinyl methyl ether) blend (40/60) Polystyrenepoly(vinyl methyl ether) blend (30/70) Polystyrenepoly(vinyl methyl ether) blend (20/80) Poly- styrenepoly(vinyl methyl ether) blend (10/90) Poly(2,6-dimethyl phenylene oxide)polystyrene blend (90/10) Poly(2,6-dimethyl phenylene oxide)polystyrene blend (80/20) Poly(2,6-dimethyl phenylene oxide)poly- styrene blend (70/30) Poly(2,6-dimethyl phenylene oxide)polystyrene blend (60/40) Poly(2,6-dimethyl phenylene oxide)polystyrene blend (50/50) Poly(2,6-dimethyl phenylene oxide)polystyrene blend (40/60) Poly(2,6-dimethyl phenylene oxide)polystyrene blend (30/70) Poly(2,6-dimethyl phenylene oxide)polystyrene blend (20/80) Poly(2,6-dimethyl phenylene oxide)polystyrene blend (10/90) Polyethersulphonepoly- (ethylene oxide) blend (40/60) Polyethersulphonepoly(ethylene oxide) blend (20/80) 14. MISCELLANEOUS Starch triacetate >Poly(ethylene-co-vinyl acetate) (14% vinyl acetate) Poly(ethylene-co-vinyl acetate) (18% vinyl acetate) Poly(ethylene-co-vinyl acetate) (25% vinyl acetate) Poly(ethylene-co-vinyl acetate) (28% vinyl acetate) Poly(ethylene-co-vinyl acetate) (33% vinyl acetate) Poly(ethylene-co-vinyl acetate) (40% vinyl acetate) Poly(ethylene-co-vinyl acetate) (65% vinyl acetate) Poly(ethylene-co-methacrylic acid) (4% metha

Conducting Polyaniline Nanoparticle Blends with Extremely Low Percolation Thresholds

Abstract: Blends of HCl-doped polyaniline (PANI.HCl) nanoparticles with the following conventional polymers, poly(vinyl chloride), polystyrene, poly(methyl methacrylate), poly(vinyl acetate), and poly(vinyl alcohol) (PVA), were prepared by suspending preformed submicronic PANI-HCl particles in the solutions of the matrix polymers and sonicating the suspension for 1.5 h. The submicronic PANI-HCl particles were prepared by oxidative dispersion polymerization using poly(vinyl methyl ether) (PVME) stabilizer. The particles contained 4.4 wt % PVME and had a conductivity of 4.96 S/cm. They had an oblong shape (250 nm×190 nm). Sonication breaks the particles to sizes less than 20 nm. The blend films exhibit an extremly low percolation threshold (f p ) in every case. The volume fraction of PANI-HCl at the percolation threshold for the above mentioned matrices lies in the range 2.5×10 -4 to 4×10 -4 . Transmission electron microscoopy of PANI-HCl-PVA blend films directly cast on carbon-coated TEM grids reveals connectivity at compositions close to f p . Self-assembly of the nanoparticles is evident from the TEM pictures

Polymers useful as pH responsive thickeners and monomers therefor

Abstract: Novel aqueous thickener or thixotropic polymers are prepared by the copolymerization of (A) about 15-60 weight percent of a C 3 -C 8 alpha, beta-ethylenically unsaturated carboxylic acid monomer, preferably acrylic or methacrylic acid or a mixture thereof with itaconic or fumaric acid, (B) about 15-80 weight percent of a nonionic copolymerizable C 2 -C 12 alpha, beta-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) about 1-30 weight percent of a new and novel nonionic ethylenically unsaturated nonionic biphillic monomer such as tristyrylpoly(ethyleneoxy) x methyl acrylate, to provide a stable aqueous colloidal dispersion at an acid pH lower than about 5.0 but becoming an effective thickener for aqueous systems upon adjustment to a pH of about 5.5-10.5 or higher. These polymers adjusted to a pH of about 5.5 or higher are effective thickeners for a wide variety of aqueous systems including cosmetic products, drilling muds, aqueous coating compositions such as latex paint, and high solids compositions such as spackle, grouts, cements, and the like.

Films having enhanced sealing characteristics and packages containing same

Abstract: Films containing a sealant layer composition comprising: (1) polyethylene homopolymer, and ethylene/alpha-olefin copolymer, ethylene vinyl acetate copolymer, and ethylene/acrylate copolymer; and (2) elastomer, plastomer, ionomer, and carboxyl-modified polyethylene; when sealed to another outer film layer comprising at least one member selected from the group consisting of ionomer, ethylene/acid copolymer, ethylene/vinyl acetate copolymer and ethylene/acrylate copolymer, have been discovered to provide a seal strength comparable to an ionomer to ionomer seal.

Process for the preparation of vinyl acetate catalyst

Abstract: A process for the manufacture of a Pd/Au/alkali metal catalyst, preferably a fluid bed catalyst used in the production of vinyl acetate comprising impregnating a microspheroidal support with a hydroxy-free metal salt solution of Pd and Au substantially free of barium and halide, reducing said salts to deposit Pd and Au on said support surface and impregnating said support with a halide-free metal salt of an alkali metal (preferably potassium).

Process for the preparation of fluid bed vinyl acetate catalyst

Abstract: A process for the preparation of a fluid bed vinyl acetate (VAM) catalyst comprising impregnating a support comprising a mixture of substantially inert microspheroidal particles with a solution comprising a metal salt of Pd and M, wherein M comprises Ba, Cd, Au, La, Nb, Ce, Zn, Pb, Ca, Sr, Sb or mixtures thereof, reducing the metal salts to form a deposit of Pd and M on the support surface and impregnating the support with at least one alkali metal salt. At least 50% of the particles used for the microspheroidal support have a particle size below 105 microns.

Reversible photodimerization of coumarin derivatives dispersed in poly(vinyl acetate)

Abstract: Four photoreactive coumarin derivatives were successfully synthesized from 7-hydroxy-coumarin and 7-hydroxy-4-methylcoumarin, i.e., 7-propionyloxy-4-methylcoumarin (M1), 7-palmitoyloxy-4-methylcoumarin (M2), 7-propionyloxycoumarin (M3), and 7-palmitoy-loxycoumarin (M4). Reversible photodimerization (350 or 300 nm) and photocleavage (254 nm) of these coumarin derivatives dispersed in poly(vinyl acetate) (PVAc) were investigated by tracing their UV absorbance variations at 310 nm. The M2 and M4 with long palmitoyl chain show much better photoreaction reversibility than M1 and M3 with short propionyl chain. Moreover, photodimerization rate (under 350 nm) of M2 is greater than 200 times of that of M1. This has been explained by the formation of suitable conformation for revers-ible photodimerization due to the hydrophobic interactions. Photodimerization of M2 is ca. 3 times quicker than that of M4, indicating 4-methyl substitution enhances pho-todimerization. The influence of photodimerization wavelength (350 and 300 nm) and photosensitizer (benzophenone) have also been investigated in detail. © 1995 John Wiley & Sons. Inc.

Vapor-Liquid Equilibria of Copolymer + Solvent and Homopolymer + Solvent Binaries: New Experimental Data and Their Correlation

Abstract: Sixty-four isothermal data sets for vapor-liquid equilibria (VLE) for polymer + solvent binaries have been obtained using a gravimetric sorption technique, in the range 23.5-80 °C. Solvents studied were acetone, acetonitrile, 1-butanol, 1,2-dichloroethane, chloroform, cyclohexane, hexane, methanol, octane, pentane, and toluene. Copolymers studied were poly(acrylonitrile-co-butadiene), poly(styrene-co-acrylonitrile), poly(styrene-co-butadiene), poly(styrene-co-butyl methacrylate), poly(vinyl acetate-co-ethylene), and poly(vinyl acetate-co-vinyl chloride). All copolymers were random copolymers. Some homopolymers were also studied: polyacrylonitrile, polybutadiene, poly(butyl methacrylate), poly(ethylene oxide), polystyrene, and poly(vinyl acetate). The composition of the copolymer may have a surprising effect on VLE.

Effects of poly(vinyl acetate) and poly(methyl methacrylate) low-profile additives on the curing of unsaturated polyester resins. I. Curing kinetics by DSC and FTIR

Abstract: The effects of two low-profile additives (LPA), poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) on the curing kinetics during the cure of unsaturated polyester (UP) resins at 110°C were investigated by using a differential scanning calorimeter (DSC) and a Fourier transform infrared spectrometer (FTIR). The effects of temperature, molar ratio of styrene to polyester CC bonds, and LPA content on phase characteristics of the static ternary systems of styrene–UP–PVAc and styrene–UP–PMMA prior to reaction were presented. Depending on the molar ratio of styrene to polyester CC bonds, a small shoulder or a kinetic-controlled plateau in the initial portion of the DSC rate profile was observed for the LPA-containing sample. This was due to the facilitation of intramicrogel crosslinking reactions since LPA could enhance phase separation and thus favor the formation of clearly identified microgel particles. FTIR results showed that adding LPA could enhance the relative conversion of polyester CC bonds to styrene throughout the reaction. Finally, by use of a microgel-based kinetic model and static phase characteristics of styrene–UP–LPA systems at 25°C, the effects of LPA on reaction kinetics regarding intramicrogel and intermicrogel crosslinking reactions, relative conversion of styrene to polyester CC bonds, and the final conversio have been explained. © 1995 John Wiley & Sons, Inc.

Hydrophilic polymer alloy, fiber and porous membrane comprising this polymer alloy, and methods for preparing them

Abstract: A hydrophilic polymer alloy which has a permanent hydrophilic nature, a sufficient mechanical strength and a high safety and which is suitable for the formation of hydrophilic porous membranes manufacturable by an industrially advantageous process can be prepared by blending an amorphous hydrophilic copolymer (X) containing 10 mole % or more of an ethylene unit, 10 to 60 mole % of a vinyl alcohol unit and 1 mole % or more of a vinyl acetate unit with a polyolefin (Y). Furthermore, this polymer alloy is also suitable for the formation of hydrophilic (porous) fibers having a sufficient mechanical strength and antistatic function.

Development of a Transdermal Delivery Device for Melatonin In Vitro Study

Abstract: The present study was undertaken to develop a transdermal delivery device for melatonin and to determine the effects of system design on the release of melatonin. Melatonin(MT) diffusion characteristics from 2 solvents through a series of ethylene vinyl acetate membranes with 4.5%, 9%, 19%, 28% vinyl acetate were characterized using vertical Franz® diffusion cells. The solvent used were 40% (v/v) propylene glycol (PG) and 40%(v/v) propylene glycol with 30%(w/v) 2-hydroxypropyl-β-cytrodextrin. The best release rate (Jss = 0.795 μg/h/cm2) was obtained from the 40% PG vehicle through the 28% vinyl acetate membrane. Melatonin diffusion through this membrane with an acrylate pressure sensitive adhesive (PSA) with and without MT loading was also studied. The data revealed an interaction between MT and the PSA in the systems with MT-loaded adhesive. A MT transdermal delivery device was constructed based on the above data. Effect of storage time (1 day, 2 days, and 3 days) on the developed device was also...

Effects of poly(vinyl acetate) and poly(methyl methacrylate) low-profile additives on the curing of unsaturated polyester resins. II. Morphological changes during cure

Abstract: The effects of two low-profile additives (LPA), poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA), on the morphological changes during the cure of unsaturated polyester (UP) resins at 110°C were investigated by an approach of integrated reaction kinetics-morphology-phase separation measurements by using a differential scanning calorimeter (DSC), scanning electron microscopy (SEM), optical microscopy (OM), and a low-angle laser light-scattering appartus (LALLS). For the UP resins cured at 110°C, adding LPA could facilitate the phase separation between LPA and crosslinked UP phases early in the reaction, and discrete microgel particles were thus allowed to be identified throughout the reaction. Microvoids and microcracks responsible for the volume shrinkage control could also be observed evidently at the later stage of reaction under SEM. Depending on the types of LPA and the initial molar ratios of styrene to polyester CC bonds, the morphological changes during the cure varied considerably. The progress of microstructure formation during reaction has been presented. Static ternary phase characteristics for the styrene–UP–LPA system at 25°C have also been employed to elucidate the resulting morphology during the cure in both the continuous and the dispersed phases. © 1995 John Wiley & Sons, Inc.

Synthesis and surface formation of three-component copolymers having polystyrene-block-poly(dimethylsiloxane) graft segments

Abstract: Two types of three-component graft copolymers, in which the geometrical arrangement of the covalently-linked three polymer segments is inverse to the order of their surface energies, were synthesized, and their surface formation behavior was studied by means of contact angle and XPS measurements. Thus, poly(vinyl alcohol) (PVA)- and polyurethane (PU)-based three-component copolymers having polystyrene (PS)-block-poly(dimethylsiloxane) (PDMS) graft segments were synthesized by means of a macromonomer technique, in which PS-block-PDMS having a vinylsilane (1) or a diol (2) group at the end of the PDMS segment were prepared through the relevant end-capping reaction of a living PS-block-PDMS copolymer. The subsequent radical copolymerization of 1 with vinyl acetate, followed by the saponification of a poly(vinyl acetate), PVAc, segment produced a PVA-based copolymer having PS-block-PDMS graft segments (4). The polyaddition of 2 with diphenylmethyl diisocyanate, followed by the chain extension with butanediol produced a PU-based three-component copolymer (5). The topmost surfaces of the sample films of 4 and 5 were found to be covered with the PDMS component having the lowest surface energy, which is positioned between the PVA (or PU) and PS segments.

Fluid bed process for the acetoxylation of ethylene in the production of vinyl acetate

Abstract: A fluid bed process for the manufacture of vinyl acetate from ethylene, acetic acid and oxygen comprising feeding ethylene and acetic acid into a fluid bed reactor through a first inlet, introducing the oxygen into the reactor through a second inlet, co-joining the oxygen, ethylene and acetic acid in the reactor in contact with a fluid bed catalyst to produce vinyl acetate. The particle size diameter of the particulate catalyst material has a range of 60% of the particles being below 200 microns (0.1 mm) with no more than 40% of the particles being below 40 microns (0.04 mm).

Oil additives, compositions and polymers for use therein

Abstract: Compositions comprising an ethylene/vinyl acetate or propionate/vinyl branched carboxylate terpolymer improve the low temperature properties of fuel oils.

On the optimization of pig pancreatic lipase catalyzed monoacetylation of prochiral diols

Abstract: The effect of various experimental variables (solvent, methodology of supportation on celite, presence of water, conversion and so on) on the rate and on the enantioselectivity of monoacetylation of some prochiral 2-substituted-1,3-propanediols with vinyl acetate catalyzed by crude PPL (pig pancreatic lipase) was analyzed. This study allowed to assess the best conditions for performing these transformations, providing an efficient methodology for the synthesis of valuable chiral building blocks with moderate amounts of inexpensive PPL, which can also be easily recycled.

Influence of polarity of polymer on inorganic particle dispersion in dielectric particle/polymer composite systems

Abstract: The influence of the polarity of polymers on the degree of dispersion of BaTiO3 particles in BaTiO3/polymer composite systems was investigated. The BaTiO3 polymer composite systems were prepared from BaTiO3 particles and low-density polyethylene (LDPE) or ethylene vinyl acetate copolymer (EVA) with 7 and 15 wt % vinyl acetate. Scanning electron microscopy observation showed that BaTiO3 particles aggregated in the polymer matrices and dispersed more readily into the EVA matrix than into LDPE. The shift of the β-peak temperature by ca. +5°C in the temperature dispersion of the loss modulus was observed for EVA–BaTiO3 composite systems in dynamic mechanical property measurement. On the other hand, the β-peak temperature of the polymers filled with graphite particles, which have hydrophobic surfaces, was almost constant in a volume fraction region of 0–0.3. The ellipsoidal axes' ratios given by comparison of experimental dielectric constant values and theoretical ones using the Maxwell equation were 4.2, 3.6, and 3.1 for LDPE/BaTiO3, EVA(7%)/BaTiO3, and EVA(15%)/BaTiO3 composite systems, respectively. The axes' ratio decreased by the introduction of polar vinyl acetate groups into nonpolar LDPE. The results confirmed that the polarity of the polymers was one of the key factors governing the dispersibility of BaTiO3 particles in the polymer matrix. © 1995 John Wiley & Sons, Inc.

High solids copolymer dispersion from a latex and its use in sealants

Abstract: A method for polymerizing predominantly one or more acrylate and/or vinyl acetate monomers in the presence of a latex results in high solids dispersions of polymer particles with lower viscosities than traditionally observed. A significant wt.% of added monomers can be present in large particles, having nonspherical shapes. Some of the original latex particles are retained during the polymerization and these increase the solids content and lower the viscosity by packing in the interstices between large particles. The total polymer solids content can easily be varied from 70 to 92 or more wt.% which are higher than achieved in any previously reported aqueous polymerizations. The viscosities at very high solids contents become paste-like but the materials still are stable to storage and further handling without breaking the dispersion into an agglomerated polymer portion and released water. The dispersions are useful to form sealants, membranes, etc., either with or without other additives. A preferred use is as an acrylate water-based caulking compound where the high solids and thixotropy of the dispersion allows for formation of a water-based caulk with low shrinkage.

Teeth-coating liquid

Abstract: The present invention provides a eeth-coating liquid comprising a color pigment represented by titanium oxide and a pearl pigment or an extender pigment represented by tricalcium phosphate, dispersed singly or in combination thereof in an alcohol series solvent, mainly ethanol with an N-methacryloylethyl-N,N-dimethylammonium-.alpha.-N-methylcarboxybetaine-butyl methacrylate copolymer, and an applicator for the coating liquid described above. This teeth-coating liquid provides excellent dispersion stability, gloss, coating property and sticking performance by using the N-methacryloylethyl-N,N-dimethylammonium-.alpha.-N-methylcarboxybetaine-butyl methacrylate copolymer singly or in combination with a shellac and a vinyl acetate resin.

Graft copolymerization in supercritical media

Abstract: A supercritical graft copolymerization process is described which includes the steps of: adding a polymer into a high pressure reactor; adding a free radically polymerizable monomer into the reactor; adding a free radical polymerization initiator; adding a sufficient amount of a supercritical solvent to dissolve at least a portion of the polymer and the monomer when supercritical conditions are achieved inside the reactor; and heating and pressurizing the reactor to achieve supercritical conditions therein for a time sufficient to effect a graft copolymerization on the polymer by the polymerizing monomer which forms at least one side chain on the polymer. In general, the reaction pressure will range from 70 atm. to 200 atm. and the reaction temperature will range from 50° C. to 90° C. In the examples provided above, the supercritical solvent was carbon dioxide. However, there is no need to limit the application to such in that the process steps will be equally applicable to other supercritical solvents which have the ability to dissolve at least a portion of the polymer and grafting monomer when at supercritical conditions in the reactor. In general, the reaction time will range from one to six hours, although shorter and longer reaction times are contemplated within the scope of this invention, the range merely being listed as the best mode known to the inventors at the time of the filing of this application. Specifically, the graft copolymerization process has been demonstrated when the polymer is a polyolefin, particularly polypropylene and poly(vinyl chloride), although other backbone polymers are certainly contemplated as within the scope of this invention. Specific examples are discussed wherein the monomer used to effect the graft copolymerization are selected from the group consisting of styrene and acrylic acid when the polyolefin polymer is polypropylene and also specifically discussed is a poly(vinyl chloride) polymer wherein the grafted polymer is based on a monomer of vinyl acetate.

Enzyme Catalysed Irreversible Transesterifications with Vinyl Acetate : Are they really Irreversible?

Abstract: When racemic β-methyl-(2-thiophene)propanol ( 1 ) was resolved via transesterification catalysed by lipase from Pseudomonas fluorescens (PFL) using an excess vinyl acetate in chloroform the enantioselectivity was high E ≈ 200 (conversion, c = 39%) when calculated from the ee of the ( S )-ester S-1Ac . However, based on the ee of the remaining ( R )-alcohol R-1 , assuming irreversibility and when measured at c = 57 %, E = 37 was obtained. Similarly, when the 5-(1-ethoxyethoxy)-3-pentyn-2-ol ( 2 ) was resolved using immobilised lipase B from Candida antarctica (Novozym SP435) under similar conditions, the ( R )-ester product R-2Ac at c = 22% gave E ≈ 140 compared with that of the remaining alcohol S-2 at c = 65 % which gave E = 15. These results are interpreted as a consequence of a reversible process occurring in transesterifications of this type, which are commonly referred to as irreversible.