Showing papers on "Polymer published in 1987"
TL;DR: The concept of mesophase polymers was introduced by as discussed by the authors, where the chains are sufficiently rigid to remain mutually aligned in the liquid phase although the perfect positional periodicity of a crystal is no longer present.
Abstract: Not much more than a decade ago, the plastics industry viewed itself as a mature branch of the heavy chemical industry. Its raison d'etre was the mass production of four or five main-line polymers, and profits were equated to tonnage output, plant efficiency, and clever downstream processing such as film blowing. The chemistry was essentially simple and the monomer, of course, cheap. There was, however, a spark of new thinking. A trend was developing toward the design and manufacture of more complex, more expensive polymers, with special properties which could command a special price. Such products would sell advanced scientific know-how, not just engineering expertise which could all too easily be exported to the major oil producers in the form of a polymer plant. Designing particular molecules to achieve desired properties is now a major theme of polymer producers. There is a move toward increasing the aromatic content of polymer backbones to achieve greater levels of chemical and thermal stability, while the development of new cross-linking systems remains as chemically intensive as ever. It is, however, the introduction of liquid crystalline polymers which, above all, has exploited the principles of molecular design, while at the same time challenging our understanding in a new area of polymer science. A polymer is “liquid crystalline” where the chains are sufficiently rigid to remain mutually aligned in the liquid phase although the perfect positional periodicity of a crystal is no longer present. In other words there is a long-range orientational order without long-range positional order (Figure 1). Structurally, therefore, the phase is intermediate between a crystal and a liquid leading to the use of the term mesophase . Where the liquid crystalline phase forms on melting the polymer, it is known as thermotropic , but where it is achieved by solvent addition it is called Inotropic. Increasing temperature, or solvent concentration, will eventually lead to the reversion of the liquid crystal phase to the normal isotropic polymer melt.
619 citations
TL;DR: In this article, the buffing process orients the polymer's molecular chains in a manner similar to cold drawing of bulk polymer samples, and the formation of a liquid-crystal phase on the crystalline, oriented polymer surface is analogous to the epitaxial growth of conventional solid crystals.
Abstract: Smetic and nematic liquid‐crystal materials can be homogeneously aligned by buffed thin films of appropriate polymers. We propose that the buffing process orients the polymer’s molecular chains in a manner similar to cold drawing of bulk polymer samples. Experimental verification of this theory is obtained by measuring buffing‐induced birefringence in thin films of various polymers coated on glass. Further experiments establish that the oriented state of the polymer chains, and not scratching or grooving of the surface, is necessary to produce alignment. Alignment is found to occur when the polymer is both oriented and crystalline. A picture of alignment is presented in which the formation of a liquid‐crystal phase on the crystalline,oriented polymer surface is analogous to the epitaxial growth of conventional solid crystals.
605 citations
TL;DR: The strength of macroscopic adhesive bonds of polymers is directly proportional to the microscopic exothermic interfacial energy changes of bond formation, as measured by Dupre's 'work of adhesion'.
Abstract: The strength of macroscopic adhesive bonds of polymers is known to be directly proportional to the microscopic exothermic interfacial energy changes of bond formation, as measured by Dupre's 'work of adhesion'. Since the work of adhesion can be very appreciably increased by interfacial acid-base bonding with concomitant increases in adhesive bond strength, it is important to understand the acid-base character of polymers and of the surface sites of substrates or of the reinforcing fillers of polymer composites. The best known acid-base bonds are the hydrogen bonds; these are typical of acid-base bonds, with interaction energies dependent on the acidity of the hydrogen donor and on the basicity of the hydrogen acceptor. The strengths of the acidic or basic sites of polymers and of inorganic substrates can be easily determined by spectroscopic or calorimetric methods, and from this information one can start to predict the strengths of adhesive bonds. An important application of the new knowledge of interfac...
521 citations
TL;DR: In this paper, thermotropic liquid crystalline polymers (LCP) are used to improve the mechanical properties of a mixture of isotropic polymers by forming highly elongated domains parallel to the flow direction.
Abstract: Melt blending of a variety of conventional isotropic polymers (both crystalline and amorphous) has shown that considerable reinforcement is obtained from the inclusion of thermotropic liquid crystalline polymers (LCP). When the LCP is a minor component it forms highly elongated domains parallel to the flow direction. The intrinsically high strength and stiffness of the LCP improve the mechanical properties of the resulting blend. This approach is distinguished from the common practice of filling polymers with chopped glass and carbon fibers by the fact that the reinforcing component comes into existence during processing (molding or extrusion). Many of the problems associated with fibrous fillers are avoided. For example, viscosity of the “in situ composite” is actually lower than that of the base polymer and wear on the compounding and processing equipment is reduced.
479 citations
TL;DR: In this paper, the authors report their success in the preparation of two polymers which are soluble in water in the doped and undoped states, which is a first for organic-solvent-soluble conducting polymers.
Abstract: It has only been within the last few months that organic-solvent-soluble conducting polymers have been developed. Previously, solubility in a mixture of arsenic trifluoride/pentafluoride was the singular path available to processability of conducting polymers. In this paper they report their success in the preparation of two polymers which are soluble in water in the doped and undoped statesexclamation Sodium poly(3-thiophene-..beta..-ethanesulfonate) (P3-ETSNa) and sodium poly(3-(thiophene-delta-butanesulfonate) (P3-BTSNa) and their respective conjugate acids are water soluble. The latter are of interest because, upon oxidation, they can lose a proton concomitant with electron loss to produce self-doped polymers; i.e., doped polymers where the counterion is attached to the polymer via a covalent bond.
398 citations
368 citations
TL;DR: In this article, the lattice energy of polymers is defined in terms of reduced molecular parameters, and it is assumed that all polymers with the same functional form for their lattice energies will be in corresponding states.
Abstract: The application of corresponding state principles to describe the properties of polymers is implicit in many of the fundamental studies of polymeric behavior. The seminal works of Prigogine, Hildebrand, Eyring, Flory, Gibbs, and DiMarzio in which multidimensional lattice representations and refined statistical mechanical approaches have been used are the basis for much of today's understanding of the thermodynamic behavior of polymers and their solutions. In this work the lattice energy of a polymer is defined in terms of reduced molecular parameters, and it is assumed that all polymers with the same functional form for their lattice energies will be in corresponding states. A reduced second order transition temperature is defined relative to a characteristic temperature T* = sϵ*/2kv* c, where the molecular parameters refer to the properties of the repeating segments of the polymer chain. Equations are derived that express the effects of molecular weight, plasticization, degree of crosslinking, and copolymerization on the second order (i.e., glass) transition temperature. In their limits, the equations are shown to reduce in form to equations derivable from free volume theory. They are also used to analyze successfully a variety of glass transition temperature data available in the literature on homogeneous uncrosslinked and crosslinked polymers, plasticized polymers, and random copolymers.
315 citations
Patent•
22 Dec 1987TL;DR: In this paper, a method and apparatus for analyzing a solution of a crystalline or a semi-crystalline polymer sample to determine a crystallinity versus weight percent profile concurrently with viscosity average molecular weight was presented.
Abstract: A method and apparatus for analyzing a solution of a crystalline or a semi-crystalline polymer sample to determine a crystallinity versus weight percent profile concurrently with viscosity average molecular weight. The polymer sample is first precipitated from solution over a cooling temperature gradient to produce a precipitated polymer sample, which is precipitated as a function of its crystallinity. The precipitated polymer sample is then eluted and redissolved over a heating temperature gradient to produce successive fractions of a fractionated polymer sample solution, which are measured to produce concentration and specific viscosity data from which the intrinsic viscosity and viscosity average molecular weight are calculated.
266 citations
TL;DR: In this article, the mechanical properties of several types of inorganic fillers were investigated in a number of different thermoplastic polymers, including General Electric's Noryl, acrylonitrile-butadiene-styrene terpolymer, polypropylene, and modified polyethylene.
Abstract: The mechanical properties of several types of inorganic fillers were investigated in a number of different thermoplastic polymers. The fillers included minerals, such as talc and silicon carbide, and metals, such as aluminum flake and stainless steel fibers. The polymers included General Electric's Noryl, acrylonitrile-butadiene-styrene terpolymer, polypropylene, and modified polypropylene. The talc and some of the aluminum flake were treated with coupling agents to improve interfacial adhesion to the polymers. The results showed that the modulus of the filled polymers was a function only of the concentration of filler used up to 40 volume percent filler. The tensile strength of the filled compositions depended very strongly on the degree of interfacial bond developed between the polymer and the filler. The interfacial bond strength depended on the effectiveness of the coupling agents and the inherent wetting ability of the polymer. Of the polymers investigated in this study, Noryl showed the greatest degree of inherent wetting to inorganic fillers. Chemical modification of polypropylene also resulted in greater adhesion to fillers. The impact strength of filled compounds had an even more complex response, because, in addition to the concentration of the filler, and strength of the polymerfiller interface, it depends on the mechanism of crack propagation.
266 citations
TL;DR: In this paper, a series of thiophene monomers 3-substituted with linear and branched alkyl chains have been synthesized, and their electropolymerization has been investigated together with the properties of the resulting polymers.
Abstract: Two series of thiophene monomers 3-substituted with linear and branched alkyl chains have been synthesized, and their electropolymerization has been investigated together with the properties of the resulting polymers. An analysis of the effects of the electrosynthesis conditions by visible absorption spectroscopy shows that the mean conjugation length presents an increasing dependence on the applied electrical conditions as the length of the alkyl chain increases. In the case of linear alkyl substituents (R3 = CH/sub 3/ to C/sub 18/H/sub 37/), the length of the alkyl chain affects slightly the polymerization reaction but produces important modifications on the structure and on the properties of the polymers. Thus, the mean conjugation length and the electrochemical reversibility admit an optimum for the polymers containing 7-9 carbons in the alkyl chain while the polymer films remain highly conductive up to R3 = C/sub 10/H/sub 21/. In contrast, the steric hindrance to conjugation caused by branched alkyl substituents totally inhibits the polymerization (isopropyl) or leads to weakly conjugated polymers (isobutyl). It is shown that the distance between the thiophene ring and the branched alkyl chain is the determining parameter which governs the aptitude for electropolymerization and the properties of the resulting polymer.
260 citations
Journal Article•
TL;DR: The review by Davis and others considers the formulation of nanoparticles, the important physicochemical variables such as pH, monomer concentration, added stabilizers, ionic strengths, etc., as well as the characteristics of the particle so created in terms of surface charge, particle size, and molecular weight.
Abstract: Alkylcyanoacrylates can be polymerized in acidified aqueous media by a process of anionic polymerization. The small particles produced tend to be monodisperse and have sizes in the range of 20 to 3000 nm depending upon the polymerization conditions and the presence of additives in the form of surfactants and other stabilizers. The polyalkylcyanoacrylate nanoparticles so produced have been studied in recent years as a possible means of targeting drugs to specific sites in the body, with particular emphasis in cancer chemotherapy. The small colloidal carriers are biodegradable and drug substances can be incorporated normally by a process of surface adsorption. The review by Davis and others considers the formulation of nanoparticles, the important physicochemical variables such as pH, monomer concentration, added stabilizers, ionic strengths, etc., as well as the characteristics of the particle so created in terms of surface charge, particle size, and molecular weight. Monodisperse particles in the range of 20 to 3000 nm can be obtained. In addition, by the use of stabilizers such as dextran and its derivatives, which can be incorporated into the nanoparticle surface by a process of polymer grafting, it is possible to make nanoparticles with interesting surface characteristics and different surface charges (sign). The stability of nanoparticles in vitro and their biodegradation in vivo are examined, and the possible formation of toxic products such as formaldehyde is highlighted. Alternative biodegradable acrylates are mentioned. Drugs can be incorporated into nanoparticles by either direct incorporation during the polymerization process or adsorption to preformed nanoparticles. The efficiency of the incorporation and the release characteristics of model compounds as well as anticancer drugs are discussed. Methods for examining these processes, including the determination of adsorption and desorption, kinetics, and isotherms, are mentioned. Selectivity in drug targeting can, in theory, be achieved by the attachment of some form of homing device, normally a monoclonal antibody or a lectin. Work in vitro and in vivo, where nanoparticles have been coated with monoclonal antibodies, is described. Finally, methods for the labeling of nanoparticles with gamma-emitting radionuclides are presented, and results obtained in animal species are given.
TL;DR: The polymerization shrinkage of a range of poly(n-alkyl methacrylates) in the range C1 to C16, some of their isomers and the polymers of cyclic and heterocyclic methacylates have been measured using densitometry to reflect the fact that the change in molar volume on polymerizing a methacRYlate ester is reasonably constant at 22 cc/mol irrespective of the geometry of the substituent group.
TL;DR: In this article, a number of commercial semicrystalline polymers have been investigated for ageing effects occurring after quenching from a high temperature T0 to various temperatures between −170°C and T0; generally T0 was kept above 100°C.
TL;DR: The first known examples of water-soluble conducting polymers are poly-3-(2-ethaneulfonate)thiophene and poly-4-butanesulfonates (3-3-butane) thiophene.
Patent•
01 May 1987TL;DR: In this article, a single step method for preparation of multi-layer polymeric delivery systems is described, in which two or three different degradable or non-degradable polymers which are not soluble in each other at a particular concentration, as dictated by their phase diagram, can be used.
Abstract: A single step method for preparation of multi-layer polymeric delivery systems. Any two or three different degradable or non-degradable polymers which are not soluble in each other at a particular concentration, as dictated by their phase diagram, can be used. The multi-layer microcapsules produced by the method are distinguished by extremely uniform dimensioned layers of polymer and actual incorporation of the substance to be delivered into the polymer layers. In the preferred embodiment of the method, two polymers are dissolved in a volatile organic solvent, the substance to be encapsulated is dispersed or dissolved in the polymer solution, the mixture is suspended in an aqueous solution and stirred, and the solvent is slowly evaporated, creating microspheres with an inner core formed by one polymer and an outer layer formed by the second polymer. In another embodiment one polymer may be formed within a layer of the other polymer by increasing the rate of evaporation of the volatile solvent.
TL;DR: The detection of large polymers of ADp-ribose in intact cells suggests that alterations in chromatin organization effected by poly(ADP-ribosylation) may extend beyond the covalently modified proteins and very likely involve noncovalent interactions of poly( ADP- ribose) with other components of chromatin.
Abstract: Methods have been developed and applied to determine the size and branching frequency of polymers of ADP-ribose synthesized in nucleotide-permeable cultured mouse cells and in intact cultured cells. Polymers were purified by affinity chromatography with a boronate resin and were fractionated according to size molecular sieve high-performance liquid chromatography. Fractions were enzymatically digested to nucleotides, which were separated by strong anion exchange high-performance liquid chromatography. From these data, average polymer size and branching frequency were calculated. A wide range of polymer sizes was observed. Polymers as large as 190 residues with at least five points of branching per molecule were generated in vitro. Polymers of up to 67 residues containing up to two points of branching per molecule were isolated from intact cells following treatment with the DNA alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine. Cells treated with hyperthermia prior to DNA damage contained polymers of an average maximum size of 244 residues containing up to six points of branching per molecule. The detection of large polymers of ADP-ribose in intact cells suggests that alterations in chromatin organization effected by poly(ADP-ribosylation) may extend beyond the covalently modified proteins and very likely involve noncovalent interactions of poly(ADP-ribose) with other components of chromatin.
TL;DR: In this article, the extrusion, fiber spinning, compression, and injection molding of blends of polycarbonate and two thermotropic liquid crystal polymers based on wholly aromatic copolyesters have been studied.
Abstract: Rheological properties, extrusion, fiber spinning, compression, and injection molding of blends of polycarbonate and two thermotropic liquid crystal polymers based on wholly aromatic copolyesters have been studied. Blends were prepared using an internal Banbury mixer and static Koch mixer. Based upon differential scanning calorimetry and dynamic mechanical measurements, these blends have been shown to be incompatible in the entire range of concentrations. During extrusion and injection molding at high strain rates, it has been observed that thermotropic liquid crystal polymer at concentrations 2.5, 5, and 10 percent by weight in situ forms high modulus and high strength fibers within the polycarbonate matrix leading to self-reinforced polymer composites. The tensile strength of the composite containing 10 percent of liquid crystal polymer exceeds that of the pure components. In addition, anisotropy of properties of the injection molded parts has been found to substantially reduce in a comparison with that of liquid crystal polymer. The processing conditions and technique for the production of self-reinforced polymer composite during processing of the blends have been identified. This has been done by measurements of mechanical properties, direct observation of morphology, and by theoretical calculation using simplified composite theory for the unidirectional continuous fiber-reinforced composites. At the high concentrations, 25 and 50 percent by weight, thermotropic liquid crystal polymer forms large spherical droplets inside polycarbonate leading to highly brittle material. This is in distinction from the fibrous, high modulus tough composites formed at the lower concentrations.
Book•
01 Jan 1987
TL;DR: In this article, the authors studied the properties of low-molecular-weight liquid-crystalline polymers and showed that the formation and properties of these polymers are related with their properties.
Abstract: 1 Structure of Comb-Shaped Polymers.- 1.1. Early Studies.- 1.2. The Amorphous State.- 1.3. The Crystalline State of Isotactic Poly(l-alkyl ethylene)s, Poly(l-alkyl ethylene oxide)s, and Poly(alkyl aldehyde)s.- 1.4. The Rotational-Crystalline State.- 1.4.1. Hexagonal Packing.- 1.4.2. d Spacings. Single- and Two-Layer Packing of the Side Chains.- 1.4.3. Heats of Fusion, Length of Crystallizable Sequences of Units, and Convergence Temperature.- 1.5. Crystallization of Comb-Shaped Copolymers.- 1.6. Supermolecular Structure.- References.- 2 Molecular Mobility in Comb-Shaped Polymers.- 2.1. Effect of the Phase State on the Relaxation Properties.- 2.1.1. Polyethylene and Isotactic Poly(l-alkyl ethylene)s.- 2.1.2. Amorphous Comb-Shaped Polymers.- 2.1.3. Crystalline Comb-Shaped Polymers.- 2.1.4. Concluding Comments.- 2.2. Rheological Properties of Comb-Shaped Poly(alkyl acrylate)s and Poly(l-alkyl ethylene)s.- References.- 3 Comb-Shaped Macromolecules in Solutions and Intramolecular Interactions.- 3.1. Optical Anisotropy.- 3.2. Conformational State and Intramolecular Mobility.- 3.3. Unperturbed Dimensions of the Macromolecules.- 3.4. Gel Formation in Solutions of Comb-Shaped Polymers.- References.- 4 Thermotropic Liquid-Crystalline Polymers.- 4.1. General Information on the Formation and Structure of Low-Molecular-Weight Liquid Crystals.- 4.2. The Liquid-Crystalline State in Linear Polymers.- 4.3. Synthesis of Liquid-Crystalline Polymers with Mesogenic Side Groups and Some Features of the Formation of Mesophases.- 4.4. Comb-Shaped Liquid-Crystalline Polymers.- 4.5. Features of the Properties of Thermotropic Liquid-Crystalline Polymers Correlated with Their Macromolecular Nature.- 4.6. Theory of the Liquid-Crystalline Ordering of Melts of Linear and Branched Macromolecules with Mesogenic Groups in the Main and Side Chains.- 4.7. Mechanisms of the Formation and Properties of the Smectic, Nematic, and Cholesteric Mesophases of Liquid-Crystalline Polymers with Mesogenic Side Groups.- 4.7.1. Smectic Mesophases.- 4.7.1.1. Chemical Structure and Thermal Properties.- 4.7.1.2. Structure of Smectic Mesophases.- 4.7.1.2.a. SA Mesophases.- 4.7.1.2.b. SB, SE, and SF Mesophases and Other Types of Structures with Translationally Ordered Groups in Layers.- 4.7.1.2.c. SC Mesophases.- 4.7.1.3. Some General Comments on the Structure of Smectic Polymers.- 4.7.2. Nematic Mesophase.- 4.7.3. Comparison of Some Properties of Smectic and Nematic Liquid-Crystalline Polymers.- 4.7.3.1. Homopolymers.- 4.7.3.1.a. The Order Parameter.- 4.7.3.1.b. Rheological Properties.- 4.7.3.1.c. Molecular Mobility in the Solid State.- 4.7.3.2. Copolymers.- 4.7.3.2.a. Copolymers of Mesogenic and Nonmesogenic Monomers.- 4.7.3.2.b. Copolymers of Two Mesogenic Monomers.- 4.7.4. The Cholesteric Mesophase.- 4.7.4.1. Optical Properties.- 4.7.4.2. The Structure of Cholesteric Polymers.- 4.8. Behavior of Liquid-Crystalline Polymers in Electrical and Magnetic Fields.- 4.8.1. Orientational Effects.- 4.8.1.1. The Concept of Electro- and Magnetooptical Effects in Low- Molecular -Weight Liquid Crystals..- 4.8.1.2. Comb-Shaped Liquid-Crystalline Polymers.- 4.8.1.2.a. The Fredericks Transition (S Effect).- 4.8.1.2.b. Orientation in a Magnetic Field.- 4.8.1.2.c. The "Guest-Host" Effect.- 4.8.1.2.d. Optical Recording of Information (Thermal Addressing).- 4.8.1.2.e. The Structural Transition Induced by an Electric Field.- 4.8.2. Electrohydrodynamic Effects.- 4.9. Behavior of Liquid-Crystalline Polymers with Mesogenic Side Groups in Dilute Solutions.- References.
Patent•
30 Sep 1987
TL;DR: A homogenous blend is formed of different water soluble polymer types, for instance of particular addition and condensation polymers, by forming one of the polymers from its monomeric starting material by polymerisation in a solution of the other polyer as mentioned in this paper.
Abstract: A homogenous blend is formed of different water soluble polymer types, for instance of particular addition and condensation polymers, by forming one of the polymers from its monomeric starting material by polymerisation in a solution of the other polyer. The resultant solution has a concentration of above 10% but is homogenous. It can be used as a bulk solution or can be dried to powder or can be present as a reverse phase dispersion.
Patent•
10 Nov 1987
TL;DR: In this paper, a mixture is obtained by mixing 5-95wt.wt.% styrene polymer with 0.05-50pts. 100pts thermoplastic resin other than component (a) (polyethylene terephthalate) and/or a rubbery polymer (b) (e.g., polyethylene rubber).
Abstract: PURPOSE:To obtain a thermoplastic resin composition improved in compatibility among components and mechanical strengths by mixing a styrene polymer with a thermoplastic polymer and/or a rubbery polymer other than said styrene polymer and a specified block or graft copolymer. CONSTITUTION:A mixture is obtained by mixing 5-95wt.% styrene polymer (a) mainly having a syndiotactic structure (e.g., PS) with 95-5wt.% thermoplastic resin other than component (a) (e.g., polyethylene terephthalate) and/or a rubbery polymer (b) (e.g., ethylene/propylene rubber). 100pts.wt. this mixture is mixed with 0.05-50pts.wt. block or graft copolymer (c) selected from among an A-B type block copolymer, an A-grafted B copolymer, a B-grafted A copolymer [wherein A is a styrene (co)polymer such as an atactic PS, an acrylonitrile/ styrene random copolymer or a styrene/maleic anhydride random copolymer, and B is a polymer such as a polyamide, polymethyl methacrylate or polyethylene terephthalate].
TL;DR: It is instructive to consider a hierarchical organization of structure in polymers at four successive levels--the molecular, nano-, micro-, and macrolevels--and to examine how interactions at and between these various levels of structure have important and often quite specific influences.
Abstract: The diversity of monomers available for synthesis of high polymers makes it possible to prepare a wide variety of long-chain macromolecular compounds. It is instructive to consider a hierarchical organization of structure in polymers at four successive levels--the molecular, nano-, micro-, and macrolevels--and to examine how interactions at and between these various levels of structure have important and often quite specific influences. Examples are drawn from semicrystalline polymers with flexible chains, liquid-crystalline polymers composed of rigid macromolecules, and amorphous polymers. Structural hierarchies in biocomposite systems are also discussed, particularly in soft connective tissues such as tendon and intervertebral disk.
Patent•
22 Jul 1987
TL;DR: In this paper, a method of treating the surface of an optical structure which comprises forming on the surface a thin layer of organic polymer using a solvent casting technique is described, and the process includes the subsequent treatment of the polymer layer with a solution of a specific ligand.
Abstract: A method of treating the surface of an optical structure which comprises forming on the surface a thin layer of organic polymer using a solvent casting technique. Preferably the process includes the subsequent treatment of the polymer layer with a solution of a specific ligand. Complex formation between the bound ligand and its specific binding partner present in a sample to be analyzed alters the optical properties of the diffraction grating surface and the change can form the basis of an assay method.
TL;DR: In this article, a series of 0.2% cross-linked copolymers (acrylic acid-methyl methacrylate) were synthesized using free-radical polymerization.
Patent•
03 Sep 1987TL;DR: In this paper, modified aqueous dispersions of water-insoluble latex polymer prepared by swelling an initial WIL polymer, prepared by emulsion polymerization, with additional ethylenically unsaturated monomer, including at least one monomer with two or more sites of ethylenic unsaturation, and subsequently polymerizing the additional monomer within the swollen latex particles.
Abstract: This invention relates to modified aqueous dispersions of water-insoluble latex polymer prepared by swelling an initial water-insoluble latex polymer, prepared by emulsion polymerization, with additional ethylenically unsaturated monomer, including at least one monomer with two or more sites of ethylenic unsaturation, and subsequently polymerizing the additional monomer within the swollen latex particles.
TL;DR: In this article, the use of nonylphenoxypoly(etheroxy) acrylates of variable poly(etheoxy) chain length has been investigated for copolymerization with acrylamide to form hydrophobically associating polymers.
TL;DR: It is shown that the magnitude of change of the partition is very small for proteins of molecular weights around 10,000, but increases almost linearly up to molecular weights of 250,000.
TL;DR: In this paper, optical and electronic properties of composites of soluble polythiophene derivatives and polystyrene over the full range of composition were reported, and the composite films were prepared by evaporating the solvent in an inert atmosphere from a solution containing both polymers.
Patent•
24 Feb 1987TL;DR: In this paper, an antistatic agent is added to the polymerization zone of a gas phase polymerization reactor in an amount sufficient to substantially reduce or prevent adherence of the polymer and/or copolymer particles to the walls of the reactor and to reduce the tendency of the polymers to agglomerate.
Abstract: A process for preventing fouling in a gas phase polymerization reactor wherein particles of polymer and/or copolymer are produced is provided. An antistatic agent is added to the polymerization zone of the reactor in an amount sufficient to substantially reduce or prevent adherence of the polymer and/or copolymer particles to the walls of the reactor and to reduce the tendency of the polymer and/or copolymer particles to agglomerate. The antistatic agent is preferably added to the polymerization zone by admixing it with a liquid carrier and introducing the resulting mixture thereto. In a continuous polymerization process wherein comonomers are copolymerized to produce particles of copolymer, the carrier used can be a liquid comonomer.
Patent•
3M1
TL;DR: In this paper, a bulk polymerization process for free radical polymerization of vinyl monomers in a wiped surface reactor is described, which permits the manufacture of pressure sensitive adhesive articles by extruding directly from the twin screw extruder onto a substrate.
Abstract: A bulk polymerization process for free radical polymerization of vinyl monomers in a wiped surface reactor is disclosed. Referring to FIG. 1; monomer streams 5 (after purification and silica gel column 2) and 7 are combined with free radical initiator 9 to form a premix 16. Pump 18 transfers the premix stream 22 through static mixer 24 into a wiped surface reactor 27. The reactor can be a counter rotating twin screw extruder which produces polymer stream 36 without the need of solvent and using residence times much shorter than prior art solution or emulsion processes. Some unique pressure sensitive adhesive acrylate polymers have been produced. They are believed to have a relatively high degree of branching. The bulk polymerization process permits the manufacture of pressure sensitive adhesive articles by extruding directly from the twin screw extruder onto a substrate.
TL;DR: In this article, the effect of the polymerization temperature on the deformation behaviour of the virgin UHMW polyethylene films is discussed within the framework of the entanglement concepts for deformation of weakly bonded macromolecules.
Abstract: The synthesis of ultra-high molecular weight polyethylene films and the production of high strength/high modulus tapes and filaments drawn directly from the virgin polymer are described. The study particularly focuses on the effect of the polymerization temperature on the deformation behaviour of the virgin UHMW polyethylene films. These results are discussed within the framework of the entanglement concepts for deformation of weakly bonded macromolecules. The developrnent of the room temperature Young's modulus and the tensile strength with draw ratio is presented and compared with modulus and tenacity/draw ratio relations observed for melt and solution crystallized polyethylene.