Showing papers on "Copolymer published in 1981"

Ferroelectric phase transition in a copolymer of vinylidene fluoride and trifluoroethylene

Abstract: The phase transition in a copolymer of 55% vinylidene fluoride and 45% trifluoroethylene near 70°C has been investigated by measuring the temperature dependence of fundamental properties. The remanent polarization disappeared near 70°C. The dielectric relaxation strength showed a peak indicating an anomaly and the dielectric relaxation time showed a critical slowing down phenomenon. A change in crystal lattice spacing associated with remanent strain and an anomalous specific heat were observed. These results are consistent with a ferroelectric phase transition. Comparison is made between observation and prediction by phenomenological and simple dipolar theories for a order-disorder type transition.

Ferroelectric-to-paraelectric phase transition of vinylidene fluoride-trifluoroethylene copolymer

Abstract: The ferroelectric properties of vinylidene fluoride‐trifluoroethylene copolymer were studied. The infrared absorption spectra and x‐ray diffraction patterns of the melt‐crystallized film suggested the similar crystalline form to the polar form I of polyvinylidene fluoride. It was found that the ferroelectric‐to‐paraelectric phase transition occurred at 70 °C and was the first order in the melt‐crystallized copolymer film by studying the dielectric constant, piezoelectric constant, D‐E hysteresis loop, and DSC measurement. The Curie constant was 2200 K. The phase transition was accompanied by the expansion of the crystal lattice.

Photosensitive block copolymer composition and elements

Abstract: Compatible photosensitive compositions, and elements made therefrom, comprising a solvent-soluble, thermoplastic, elastomeric, block copolymer, a nongaseous ethylenically unsaturated compound, and an addition polymerization initiator activatable by actinic light are useful in preparing printing plates, particularly flexographic printing plates, and other relief images.

High vinyl polybutadiene or styrene-butadiene copolymer

Abstract: OF THE DISCLOSURE High vinyl polybutadiene or styrene-butadiene copolymer obtained by polymerizing 1,3-butadiene alone or with styrene in a hydrocarbon solvent using an organolithium compound as an initiator and coupling the resulting polymer, characterized in that (1) the polybutadiene or styrene-butadiene copolymer comprises at least 20% by weight of a polymer having in its molecular chain a linkage between butadienyl and at least one element selected from the group consisting of silicon, germanium, tin and lead, (2) the styrene content of said copolymer is 40% by weight or less, and (3) the polybutadiene or the butadiene portion of the styrene-butadiene copolymer has a vinyl content of 50 to 95%. Said polybutadiene or sytrene-butadiene copolymer has a low rolling resistance, high wet skid resist-ance, highly improved fracture property and, an excellent processability.

Compatibilized polymer blends

Abstract: Compatibilized polymer blends are described comprising a blend of olefin polymer, nitrile rubber, and a compatibilizing amount of block copolymer comprising nitrile rubber compatibilizing segments and olefin polymer compatibilizing segments.

Thermoplastic resin composition

Abstract: PURPOSE:To prepare the titled compositon having excellent impact strength and high-temperature moldability,by compounding a block copolymer of a conjugated diene and a vinyl aromatic hydrocarbon with a specific amine stabilizer or a mixture of said stabilizer and a radical polymerization inhibitor. CONSTITUTION:The objective composition is prepared by compounding (A) a thermoplastic resin with (B) a block copolymer of a conjugated diene and a vinyl aromatic hydrocarbon and (C) an amine stabilizer having at least one nitrogen atom and one sulfur atom in the molecule or a mixture of said stabilizer and a radical polymerization inhibitor. The amount of the component (C) is 0.001-10pts.wt. per 100pts. of the component (B). The weight ratio of the amine stabilizer to the radical polymerization inhibitor is 99/1-10/90, and the radical polymerization inhibitor is pref. hydroquinone, hydroquinone monoalkyl ether, etc. A high-density polyethylene resin, a fluororesin, etc. can also be used effectively as the component (A).

Emulsion Polymerization of Vinyl Acetate

Abstract: 1. Frontiers Between Theory and Industrial Practice in Vinyl Acetate Polymerizations.- 2. The Polymerization of Aqueous Solutions of Vinyl Acetate.- 3. Effects of Particle Number and Initiator Level on the Kinetics of Vinyl Acetate Emulsion Polymerizations.- 4. Synthesis Kinetics and Characterization of Poly(Vinyl Acetate)- Molecular Weight and Long Chain Branching Development.- 5. Some Surface Chemical Effects on the Capture of Free Radicals-A Kinetic Parameter Analysis of the LPS Model.- 6. The Reinvestigation of Vinyl Acetate Emulsion Polymerization (I)- The Rate of Polymerization.- 7. The Reinvestigation of Vinyl Acetate Emulsion Polymerization (II)-The Induced Decomposition of Initiator.- 8. The Reinvestigation of Vinyl Acetate Emulsion Polymerization (III)-Isotope Effect.- 9. The Radiation Induced Emulsion Polymerization of Vinyl Acetate.- 10. The Stabilization of Poly(Vinyl Acetate) Latexes by Polymethacrylic Acid.- 11. Particularities of Emulsion Polymerization of Vinyl Acetate in the Presence of Hydroxyethylcellulose.- 12. Preparation, Characterization and Properties of Vinyl Acetate- Butyl Acrylate Copolymer Latexes.- 13. Some Studies on Vinyl Acrylic Latex-Surfactant Interactions.

Apparatus for separating blood

Abstract: An apparatus for separating blood is provided with a closed end and a thixotropic gel-like sealant with a specific gravity intermediate between the gravities of serum and clot phases. A cavity is formed on the upper surface of said sealant. The sealant consists essentially of an α-olefin-dimaleate copolymer having a viscosity from 10,000 to 120,000 c.p. (25° C.), to which a viscosity-specific gravity adjusting agent is added to adjust the specific gravity to 1.035-1.055. The cavity is formed in such a size that diameter of the upper surface is from 0.15 to 0.7 times the inner diameter of the apparatus and its depth is from 0.13 to 0.65 times the thickness of said sealant.

Rubber composition for tire

Abstract: of the Disclosure A rubber composition for tire having low rolling resistance and high wet skid resistance, breakage strength and wear resistance consists mainly of a rubber component containing at least 20 parts by weight of a high vinyl butadiene-styrene copolymer rubber obtained by copolymeriz-ing randomly styrene with 1,3-butadiene, and containing 3-30% by weight of bonded styrene and 60-95% by weight of 1,2-bond in butadiene unit, and further containing metal-butadienyl bonds in its main chain in a weight fraction of at least 20% by weight

Copolymerization of styrene with acrylamide in an emulsifier‐free aqueous medium

Abstract: Copolymerization of styrene with acrylamide was carried out in an emulsifier-free aqueous medium. The resulting latex contained an appreciable amount of acrylamide-rich copolymer in the serum. The copolymerization course was divided into three stages on the basis of the main reaction locus. At first, acrylamide polymerized in preference to styrene in the aqueous phase. Water-soluble growing radicals lost hydrophilicity rapidly and nucleated the particles. After particle formation, styrene polymerized exclusively in the particles until styrene droplets disappeared. The decrease in the concentration of residual styrene monomer caused growing radicals to keep the hydrophilicity for a long time, and polymerization of acrylamide was accelerated in the aqueous phase. Polymerizations at higher temperature and lower pH resulted in prolongation of the first stage of the polymerization, that is, preferential polymerization of acrylamide in the aqueous phase. An increase in the acrylamide fraction in monomer feed caused some decreases in the particle size and its uniformity.

Polymer blends containing polymer of β-hydroxybutyric acid and chlorine or nitrile group containing polymer

Abstract: Polymer blends containing (i) 0.2-95% by weight of a high molecular weight β-hydroxybutyric acid homo- or copolymer and (ii) a polymer containing at least 25% by weight of chlorine or nitrile groups, such as chlorinated polyethylene, polyvinyl chloride, or a high acrylonitrile resin. In small quantities the β-hydroxybutyric acid polymer acts as a processing aid for the chlorine or nitrile containing polymer. In larger quantities the properties of the β-hydroxybutyric acid polymer or the chlorine or nitrile containing polymer are improved.

Styrene‐divinylbenzene copolymers, 3. Revisited IR analysis

Abstract: A critical analysis of the styrene-divinylbenzene resin infra-red spectra was made using previous works and new results. A method for the determination of pendent double bonds and also crosslinking degree and composition of the resin is drawn. A few examples of application are given.

Polymers primarily for contact lenses, and contact lenses made from them

Abstract: The invention relates to new monomers of polysiloxanyl alkyl esters of acrylic and methacrylic acids and their copolymerization with alkyl esters of acrylic or methacrylic acids and/or itaconate esters to produce highly oxygen- permeable material primarily for contact lenses. The copolymer will include 10% to 60% of the silicon-containing monomer or monomers; preferred such monomers are tris(non amethyltetrasiloxanyl) methacryloxypropylsilane) or bis(decamethylpentasiloxanyl)di(methacryloxypropyl- methylsilane). The copolymer preferably includes a cross-linking agent and hydrophilic monomer. Contact lenses manufactured from the material are machined and polished into hard or semi-hard contact lenses having dimensional stability.

Thermoformable polymer blend composition

Abstract: A thermoformable polymer blend composition comprising at least 50% by weight of an olefin polymer such as polyethylene or polypropylene, from 10 to 48% by weight of a styrene polymer and from 2 to 40% by weight of a thermoplastic styrenic block copolymer rubber, preferably a styrene-butadiene-styrene block copolymer, which acts as a compatibilizer for the olefin and styrene polymers in the blend. This blend can be formed on conventional machinery to give products having the beneficial properties of both types of polymers.

Organic solution of fluorinated copolymer having carboxylic acid groups

Abstract: An organic solution of a fluorinated copolymer having carboxylic acid groups comprises the copolymer of fluorinated ethylenically unsaturated monomer and a functional monomer having carboxylic acid group (--COOH group) dissolved in a hydrophilic organic solvent with a small amount of water.

Chemistry of miscible polycarbonate–copolyester blends

Abstract: Blends of polycarbonate and the copolyester based on 1,4-cyclohexanedimethanol and a mixture of terephthalic and isophthalic acids are known to be completely miscible. This study was concerned with various chemical events which may occur in this system, particularly during melt processing. Degradation reactions were studied by both TGA and dilute viscometry techniques, and some indications of component interaction were noted. The residual titanium catalyst from the copolyester formation was found to produce color formation by interaction with phenolic end groups in the polycarbonate and to promote interchange reactions. Both events could be suppressed by deactivation of the residual catalyst with appropriate additives. An indication of the extent of interchange reactions was obtained by following the crystallizability of the copolyester component using differential scanning calorimetry.

Polymer compositions and laminates produced by bonding or coextrusion

Abstract: Compatible blends of polymers are disclosed which contain (a) a low density ethylene polymer, (b) a copolymer of ethylene and an alkyl ester of acrylic or methacrylic acid or vinyl acetate, (c) an ionomer resin, and (4) optionally a tackifying resin such as a glyceryl ester of a rosin acid.

Thermoformable polymer blend composition comprising styrene polymer, olefin polymer and block copolymer

Abstract: A thermoformable polymer blend composition comprising at least 50% by weight of an olefin polymer such as polyethylene or polypropylene, from 10 to 48% by weight of a styrene polymer and from 2 to 40% by weight of a thermoplastic styrenic block copolymer rubber, preferably a styrene-butadiene-styrene block copolymer, which acts as a compatibilizer for the olefin and styrene polymers in the blend. This blend can be formed on conventional machinery to give products having the beneficial properties of both types of polymers.

Copolymerization of styrene with acrylamide derivatives in an emulsifier-free aqueous medium

Abstract: Acrylamide derivatives were copolymerized with styrene in an emulsifier-free aqueous medium, and the copolymerization mode and the characteristics of the resulting latices were compared with those of a styrene–acrylamide copolymerization system. In their copolymerization mode, N-(hydroxymethyl)acrylamide and N,N-dimethylacrylamide resembled acrylamide, and their heterogeneous copolymerization course was divided into three stages on the basis of the main reaction locus. Copolymerization of styrene–methacrylamide did not resemble that of the others. The interfacial property and reactivity of acrylamides affected not only the polymerization mechanism but also the latex properties, e.g., particle size, distribution of acrylamides units in the latex, etc. The narrowest distribution of particle size was obtained in styrene–N-(hydroxymethyl)acrylamide copolymerization at a monomer ratio of 10:1. Delayed addition of styrene into the aqueous solution of N-(hydroxymethyl)acrylamide prepolymerized to some extent was found to be effective in preparing a latex with nearly monodisperse and large particles.