Showing papers on "Polymer published in 1985"

Encyclopedia of polymer science and engineering

Abstract: Cellular Materials Cellulose Cellulose, Biosynthesis Cellulose, Graft Copolymers Cellulose, Microcrystalline Cellulose Derivatives Cellulose Esters, Inorganic Cellulose Esters, Organic Cellulose Ethers Cement Additives Chain-Reaction Polymerization Chain Transfer Characterization of Polymers Charge-Transfer Complexes Chelate- Forming Polymers Chemical Analysis Chemically Resistant Polymers Chitin Chloroprene Polymers Chlorotrifluorethylene Polymers Chromatography Classification of Polymerization Reactions Coating Methods Coatings Coatings, Electrodeposition Cold Forming.

Polymers of N-vinylpyrrolidone: Synthesis, characterization and uses.

Abstract: Polyvinylpyrrolidone (PVP) having molecular weights (Mw) from 2500 to about 1 million is mainly obtained by radical polymerization in solution The higher molecular weight type products are polymerized in aqueous solution mostly using hydrogen peroxide as initiator The polymers thus obtained have hydroxyl and carbonyl end groups More stable end groups can be obtained by polymerization in solvents, which may act as chain transfer agents and which produce low molecular weight type products Copolymers especially with monomers such as vinyl acetate and with various acrylic compounds may also be produced by solution polymerization Popcorn polymerization leads to insoluble PVP Thereby VP is polymerized without initiator in the presence of small amounts of bifunctional monomers The polymeric flakes thus formed are highly cross-linked, mainly due to entanglements The molecular weight distribution of soluble PVP is broad due to transfer reactions An unusual property of PVP is its solubility in water as well as in various organic solvents The glass transition temperature of high molecular weight polymers (Mw=1 million) is about 175°C and falls to values under 100°C with decreasing molecular weight Mw=2500) PVP forms complexes with various compounds, especially with H-donors such as phenols and carboxylic acids The complex formed with cross-linked PVP and polyphenols is used commercially for the clarification of beverages Another commercial use is the complexation of iodine with linear PVP, which leads to effective disinfectants of very low toxicity Further important applications of PVP in the pharmaceutical field are their use as binding or film forming agents for tablets, and as solubilizing agents for injections The swelling ability of cross-linked PVP in water is used in disintegrating agents for tablets In the cosmetic field VP polymers are used as film formers for hair dressing products Examples of technical applications are adhesives, textile auxiliaries and dispersing agents

Microencapsulation of water soluble active polypeptides

Abstract: This invention concerns novel sustained release microcapsule compositions comprising water-soluble, hormonally active polypeptides and, optionally, a polymer hydrolysis modifying agent encapsulated in a biocompatible, biodegradable polymer.

Plasticization of glassy polymers by CO2

Abstract: A technique is described which uses differential scanning calorimetry to estimate the glass transition of polymers containing a dissolved gas. The technique is simple and appears to give reliable results. The effects of CO2 sorption at pressures up to 25 atm were examined in detail for poly(methyl methacrylate) and its blends with poly(vinylidene fluoride). Less extensive results for polystyrene, polycarbonate, poly(vinyl chloride), and poly(ethylene terephthalate) are also given. Reductions in Tg of up to 50°C are observed. A theoretical relation by Chow predicts results in reasonable agreement with the experimental data. These findings are relevant to various applications such as membrane separation processes for gases.

Particle size control in dispersion polymerization of polystyrene

Abstract: In a dispersion polymerization process, the reaction mixture starts out as a homogeneous solution and the resulting polymer precipitates as spherical particles, stabilized by a steric barrier of di...

Recent advances in liquid crystalline polymers

Abstract: I: Synthesis, Structure, Properties Relationships.- 1. Synthetic Routes to Liquid Crystalline Polymers.- 2. Chiral Thermotropic Liquid Crystal Polymers.- 3. Solid State Physics of Thermotropic Polyesters: Internal Friction of Mesomorphic Structures.- 4. Thermotropic Liquid Crystal Aromatic Copolyesters Containing Cycloaliphatic Units.- 5. Polymerization of Allyldimethyldodecylammonium Bromide Liquid Crystalline Monomer to Its Liquid Crystalline Polymer.- II: Theory.- 6. Theoretical Basis for Liquid Crystallinity in Polymers.- 7. Nematic Liquid Crystals Formed from Flexible Molecules: a Molecular Field Theory.- 8. Order and Odd-Even Effects in Thermotropic Nematic Polyesters.- III: Characterization.- 9. Structure and Characterization of Thermotropic Liquid Crystalline Polymers.- 10. Observations on the Rheology of Thermotropic Polymer Liquid Crystals.- 11. Rheo-Optical Studies of the Thermotropic Aromatic Copolyesters of Poly(Ethylene Terephthalate) and p-Acetoxybenzoic Acid.- 12. Electron Microscopy of Thermotropic Copolyesters.- 13. Nuclear Spin-Label Studies of Liquid Crystal Polymers.- 14. Viscosity and the Thermodynamic Properties of Liquid Crystalline Polymers with Mesogenic Side Groups.- 15. Measurement of Orientational Order in Liquid Crystalline Samples by NMR Spectroscopy.- 16. Phase Behaviour of Dye-Containing Liquid Crystalline Copolymers and Their Mixtures with Low Molecular Weight Liquid Crystals.- 17. Dielectric Relaxation Measurements and X-ray Investigations of Liquid Crystalline Side-Chain Polymers.- 18. Structural Investigations on Liquid Crystalline Side-Chain Polymers.- 19. Macromolecular Order and Conformation in the Solid and Nematic Phases of Semi-Rigid Polymers and Polymer-Monomer Mixtures-NMR Study.- IV: Applications.- 20. Aramids-Bridging the Gap between Ductile and Brittle Reinforcing Fibres.- 21. Towards a Photoconductive Liquid Crystal: Carbazole-Containing Systems.- 22. Electro-Optic Effects in a Smectogenic Polysiloxane Side-Chain Liquid Crystal Polymer.

Hydrogel-forming polymer compositions for use in absorbent structures

Abstract: The present invention relates to improved hydrogel-forming polymer compositions which can be used as absorbents in absorbent structures and absorbent articles such as diapers, sanitary napkins and the like. Such hydrogel-forming polymer compositions are substantially water-insoluble, slightly cross-linked, partially neutralized polymers which are prepared from unsaturated polymerizable, acid group-containing monomers and cross-linking agents. These hydrogel-forming polymer materials, upon imbibing fluids, form hydrogels. Such polymer materials have relatively high gel volume and relatively high gel strength as measured by shear modulus of the hydrogel which forms therefrom. Such polymer materials also contain relatively low levels of extractable polymer material which can be extracted therefrom by contact with synthetic urine. Preferred hydrogel-forming polymers having these characteristics can be prepared by polymerizing the acid group-containing monomers in their free acid form at relatively low monomer concentrations, preferably using relatively low polymerization temperatures. Absorbent structures and absorbent articles containing these dried hydrogel-forming polymer materials are also disclosed.

Polymer decoration: The orientation of polymer folds as revealed by the crystallization of polymer vapors

Abstract: A new technique of decoration of the fold surface of polymer crystals is described. It is similar in methodology to gold decoration, but makes use of vapors of crystallizable polymers, principally polyethylene, as decorating material. Upon condensation and crystallization, the highly anisometric decorating molecules become oriented parallel to the fold direction. They build up small crystalline lamellae which, seen edge-on, appear as elongated rods and can be easily observed by conventional transmission electron microscopy. This decoration technique reveals the sectorization of polymer single crystals grown from solution. It can be used to determine the local fold orientation (with a resolution of ca. 10 nm) of polymers crystallized under a wide range of conditions, including crystallization from the bulk. The technique reveals that under all crystallization conditions so far investigated the outermost part of the polymer fold surface is relatively ordered, and the folds and/or loops are, as a rule, oriented nearly parallel to the macroscopic growth front.

Chemical Modification of Matrix Resin Networks with Engineering Thermoplastics. 1. Phenolic Hydroxyl Terminated Poly(Aryl Ether Sulfone)-Epoxy Systems,

Abstract: Functionally terminated bisphenol-A polysulfone oligomers were used in the modification of Epon Resin 828/4,4′-diamino-diphenylsulfone (DDS) network system. Phenolic hydroxyl terminated PSF oligomers were first capped with a large excess of bisphenol-A diglycidyl ether or Epon Resin 828 at both ends and then the resulting system was cured with DDS, in a two-step process. During these studies molecular weight and the amount of PSF oligomers incorporated into the network were varied and their effect on the overall properties of the resulting systems were investigated. The capping and curing reactions were followed by using FT-IR and NMR spectroscopy, GPC, HPLC and DSC techniques. As a function of the oligomer molecular weight, SEM studies showed the formation of two-phase structures with ductile PSF particles dispersed in the continuous epoxy matrix. Mechanical characterization and fracture toughness measurements showed a remarkable increase in KIC or gIC values of the modified networks over that of control, without significant loss in the modulus. This work would appear to be one of the first studies where well bonded ductile glassy modifiers have significantly improved the fracture toughness of highly crosslinked networks.

Synergistic scale and corrosion inhibiting admixtures containing carboxylic acid/sulfonic acid polymers

Abstract: The instant invention is directed to an admixture, and its use in inhibiting scale and corrosion in aqueous systems, comprising: (a) a water-soluble polymer having a weight average molecular weight of less than 25,000, as determined by low angle laser light scattering, comprising an unsaturated carboxylic acid and an unsaturated sulfonic acid, or their salts, having a ratio of 1:20 to 20:1, and (b) at least one compound selected from the group consisting of water-soluble polycarboxylates, phosphonates, phosphates, polyphosphates, metal salts and sulfonates. The instant invention is also directed to a method of inhibiting the formation of insoluble alluvial, metal oxide and metal hydroxide deposits in an aqueous system, comprising adding to the system at least 0.1 mg/l of a water-soluble polymer having a weight average molecular weight of less than 25,000, as determined by low angle laser light scattering, comprising an unsaturated carboxylic acid and an unsaturated sulfonic acid, or their salts, having a ratio of 1:20 to 20:1 and a phosphonate.

Magnetic Monosized Polymer Particles for Fast and Specific Fractionation of Human Mononuclear Cells

Abstract: Magnetic monodisperse polymer particles were developed and the necessary conditions established to use them for both quantification and fractionation of human peripheral blood mononuclear cell populations. The particles consist of a styrene divinylbenzene core into which magnetite has been deposited by an in situ oxidation process. Thereafter the core has been coated with a hydrophilic polymer containing epoxy and hydroxyl groups. The particles have strong nonspecific binding capacity for protein and can be coated with the appropriate antibodies by physical adsorption only. However, the hydroxyl groups on the outer polymer also make covalent coupling possible. After appropriate blocking they can be used in a rosette assay for quantification of mononuclear leukocytes previously sensitized with monoclonal antibodies. Furthermore, a suitable magnet makes it possible to deplete the cell suspension efficiently of the rosette-forming cells. We have thoroughly investigated the functional properties of human mononuclear cells depleted of T lymphocytes by this technique. Our results show that T cells are virtually completely eliminated, as demonstrated by flow cytometry and various functional assay systems.

High-strength polyethylene fibres from solution and gel spinning

Abstract: There are many recent reports in the literature of high-strength, high-stiffness polyethylene fibres produced by a variety of techniques, all of which involve at some stage crystallizing the polymer (invariably a high molecular weight material) from solution. In this review we try to place these reports in their proper context and to show how and why the various techniques have been developed. To do this we present brief historical reviews of two distinct subjects: the drawing of single-crystal mats and the preparation of “shish kebabs”. Both of these have, when used in conjunction with very high molecular weight material, led to very strong and stiff fibres. We then describe the recent gel spinning techniques and arrive at the conclusion that there are essentially just two distinct processes involved: the solid state deformation of single crystals, and the crystallization of pre-extended chains to form shish kebabs. Either or both of these processes can occur in gel spinning. In addition to the scientific subject some technical aspects, including material from the patent literature, are also covered.

Method for continuous production of cross-linked polymer

Abstract: A method for the continuous production of a cross-linked polymer having a low proportion of large particles, comprising the steps of continuously feeding the aqueous solution of a monomer capable of being converted by aqueous solution polymerization into a water-containing cross-linked gel polymer and a polymerization initiator to a vessel provided with a plurality of mutually parallel rotary stirring shafts each fitted with stirring blades, finely dividing a water-containing gel polymer issuing from the polymerization in progress by the shearing force of stirring blades generated by the rotation of said stirring shafts while allowing the radical aqueous solution polymerization to proceed without interruption, and continuously discharging the resultant finely divided water-containing gel polymer out of said vessel.

Low temperature embedding with Lowicryl resins: two new formulations and some applications

Abstract: Lowicryl K4M and HM20 are methacrylate/acrylate based low temperature embedding resins for biological material which can be used in conjunction with either the progressive lowering of temperature (PLT) technique or with freeze-substitution. K4M and HM20 are applicable over a very extended temperature range, approximately 220 K to 340 K. With two new resins, K11M and HM23, one can reach even lower temperatures, c. 200 K. Freeze-substitution combined with low temperature embedding allows for very mild or no chemical fixation which seems to increase the sensitivity of immunocytochemical localization of antigens on sections.

Conjugates of pharmaceutically useful proteins

Abstract: A conjugate comprising a pharmaceutically useful protein linked to at least one water-soluble polymer by means of a reversible linking group.

Liquid crystalline polymer compositions, process, and products

Abstract: Novel compositions comprising a high concentration of one or more extended chain homopolymer, copolymer, or block polymer and certain polyphosphoric acids are prepared. Such compositions are optically anisotropic (liquid crystalline), capable of exhibiting excellent cohesive strength, and are especially suited to the production of high molecular weight ordered polymer fibers by dry-jet wet spinning. These liquid crystalline compositions are capable of being drawn through long air gap distances and spun at exceptionally high spin draw ratios. Fibers, films and other articles formed from these liquid crystalline compositions exhibit exceptionally high physical and heat resistant properties.

Hydrophilic-hydrophobic copolymers as cell substrates: Effect on 3T3 cell growth rates

Abstract: Cell-substrate interactions are important in many processes, including biocompatibility, marine biofouling, cell growth in culture, and cell separation. The influence of surface properties such as polarity, hydrophobic/hydrophilic or acid/base balance on cell interactions is poorly understood, however. In this study 2-hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA) in various volume ratios were copolymerized and spun cast onto glass to produce a chemically homologous series of surfaces varying principally in hydrophilicity. Growth, spreading, and attachment of mouse 3T3 cells were measured with time-lapse photomicroscopy, visualization of the nucleolus, and [3H]thymidine labeling, respectively. Fibronectin adsorption from serum to the copolymers was also measured, using 125I-labeled fibronectin. On all polymers made with monomers containing 50% or more EMA, cell numbers increased logarithmically with time at the same rate observed for glass (21-hr doubling time). Cells on 40% EMA polymers remained virtually constant in number while decreases in cell number were observed on all polymers made with 30% or less EMA. Attachment measured after either 2 or 20 hr was not well correlated with growth behavior since significant attachment occurred on polymers on which growth had not occurred. Spreading at 2 hr but especially after 24 hr was very similar to the variation in growth. The kinetics of attachment and spreading varied markedly among the copolymers. Fibronectin adsorption varied from 0.1 to 1.5 ng/cm2 on the copolymers and was similar to the variation in 2-hr spreading. Fibronectin adsorption from the serum and fibronectin exudation by the cells both appear to be important in determining 3T3 cell interactions with the HEMA-EMA copolymers. However, the relative influence of these two processes on cell behavior probably varies greatly among the copolymers. The interfacial properties of the copolymers which could account for a variation in the ability to support cell growth are discussed.