Showing papers on "Polymer blend published in 1989"

Surface enrichment in an isotopic polymer blend.

Abstract: Forward-recoil spectrometry reveals that the surface of a blend of deuterated polystyrene ($d$-PS) and protonated polystyrene (PS) is enriched with $d$-PS relative to the bulk; the surface excess of $d$-PS increases almost linearly with the bulk volume fraction $\ensuremath{\varphi}$ of $d$-PS at 184\ifmmode^\circ\else\textdegree\fi{}C. The results may be interpreted quantitatively with mean-field theory, and yield a form of the bare surface energy of the blend consistent with the surface enrichment being driven by a surface-energy difference between $d$-PS and hydrogenated polystyrene ($h$-PS) of isotopic origin.

Polymer mixture comprising an aromatic polycarbonate, a styrene-containing copolymer and/or graft polymer and a phosphate based flame-retardant; articles formed therefrom

Abstract: The invention relates to a polymer mixture which comprises an aromatic polycarbonate, a styrene­-containing copolymer and/or a styrene-containing graft polymer and a flame-retardant. It has been found that the use of a certain type of flame-retardants, namely oligomeric phosphates leads to a polymer mixture having improved properties. In particular to a polymer mixture having a good combination of flame retardancy, non-­juicing characteristics of the flame retardant, good plastifying effect and good heat resistance.

Polymer mixture having aromatic polycarbonate styrene I containing copolymer and/or graft polymer and a flame-retardant, articles formed therefrom

Abstract: The invention relates to a polymer mixture which comprises an aromatic polycarbonate, a styrene-containing copolymer and/or a styrene-containing graft polymer and a flame-retardant. It has been found that the use of a certain type of flame-retardants, namely oligomeric phosphates leads to a polymer mixture having improved properties. In particular to a polymer mixture having a good combination of flame retardancy, non-juicing characteristics of the flame retardant, good plastifying effect and good heat resistance.

Extrudable thermoplastic hydrocarbon polymer composition

Abstract: An extrudable composition comprising hydrocarbon polymer, organophosphite or organophosphate compound and fluorocarbon polymer. The organophosphite or organophosphate and the fluorocarbon polymer are present in the composition in such relative proportions and concentrations as to reduce the occurrence of melt defects during the extrusion of said thermoplastic hydrocarbon polymer.

Optical techniques to characterize polymer systems

Abstract: FTIR-spectroscopy of polymers (J.L. Koenig). Studies by FTIR spectroscopy of molecular orientation in monomolecular layers of polymers on solid substrates (T. Arndt, G. Wegner). Glass dynamics probed by motional line narrowing of reactions in polymers via absorption spectroscopy of photochromism (R. Richert). Photoelectron spectroscopy of polymers (K. Seki). Site-selective fluorescence spectroscopy of polymers (H. Bassler). Triplet state spectroscopy of polymers (R.D. Burkhart). Polymers in solids: structure and interactions measured by electronic excitation transport (K.A. Peterson et al.). Nonlinear optical spectroscopy of polymers (E. Cavicchi et al.). Resonance Raman spectroscopy of conjugated polymers (D.N. Batchelder). Brillouin spectroscopy and its application to polymers (J.H. Kruger). Photon correlation spectroscopy of amorphous bulk polymers and compatible polymer blends (G. Meier, G. Fytas). Synchrotron radiation X-ray scattering (M.H.J. Koch). Subject Index.

Atlas of Polymer Morphology

Abstract: This book will be useful to those involved in optical transmission and scanning electron microscopy (SEM) studies of polymers. The chapters include methods for morphological investigations and determination of fine structure (crystallinity, orientation) in various types of polymers and polymer blends. The effects of processing, mechanical deformation chemicals, and other agents are presented. Includes 442 micrographs. -- AATA

Graft copolymers and blends thereof with polyolefins

Abstract: A novel graft copolymer capable of imparting to a polyolefin when blended therewith high tensile modulus and high sag resistance without increasing melt viscosity, and a method of making the same. The graft copolymer is a polyolefin having a relatively high weight-average molecular weight methacrylate polymer grafted thereto. The graft copolymer is formed by dissolving or swelling a non-polar polyolefin in an inert hydrocarbon solvent, heating to dissolve the polyolefin, and while stirring the mixture, adding a methacrylate monomer, together with an initiator to produce a constant, low concentration of radicals, to form a graft copolymer with a high molecular weight polymer chain covalently bonded or grafted to the polyolefin backbone. The graft copolymer can be separated from the solvent, isolated by volatilizing the solvent, for example in a devolatilizing extruder, and extruded into a desired shape such as a sheet, tube or the like. This graft copolymer can be blended with a poolyolefin matrix. The blend exhibits improved physical properties in the melt, upon cooling, and in the solid state, and is useful in cast and oriented films, solid extruded rod and profile, foamed rod, profile and sheet, blown bottles and the like. The graft copolymer further improves compatibility in a wide range of polymer blends.

Evidence for cleavage of polymer chains by crack propagation

Abstract: CRACK propagation in polymers is a topic of considerable importance to the technological application of these materials. In high-molecular-weight glassy polymers, crack propagation is normally assumed to require the breaking of covalent bonds in polymer chains that span the crack path, as opposed to chain slip and disentanglement. The fraction of such broken chains in a bulk sample would be very small, however, so that there is little direct evidence for this chain breakage1. Interfaces between immiscible polymers are often very weak, but can be strengthened by the presence of a diblock copolymer (a polymer in which each molecule consists of a block of one polymer bonded to a block of a different polymer) for which each of the two blocks is miscible with one of the homopolymers2. The diblock copolymer is thought to organize at the interface and so 'stitch' the homopolymers together. Here we show that crack propagation along the interface between the homopolymers involves breaking all the copolymer chains at a point in the region of the junction between the two blocks. Thus we demonstrate both that the block copolymer does indeed organize at the interface and that fracture involves the breaking of polymer chains. This information may suggest means by which the mechanical properties of polymer blends could be systematically improved.

Ink composition containing a blend of a polyester and an acrylic polymer

Abstract: Disclosed is a novel blend of a water-dissipatable polyester material and an acrylic polymer. The acrylic polymer must be compatible with the polyester and can be optionally styrenated. The polyester is exemplified in having an acid component of from about 75 to about 84 mole % isophthalic acid and conversely from about 25 to about 16 mole % 5-sodiosulfoisophthalic acid, and having a glycol component of from about 45 to about 60 mole % diethylene glycol and conversely from about 55 to about 44 mole % 1,4-cyclohexanedimethanol or ethylene glycol or mixtures thereof. The polymer blends are useful for preparing ink compositions having improved block resistance and water resistance.

Bulk, surface, and blood-contacting properties of polyetherurethanes modified with polyethylene oxide.

Abstract: —The bulk, surface, and blood-contacting properties of a series of polyether polyurethanes based on polyethylene oxide (PEO) (MW = 1450), polytetramethylene oxide (PTMO) (MW = 1000), and mixed PEO/PTMO soft segments were evaluated. The effect of varying the weight percentage of PEO, and thus the overall polarity of the mixed soft segment phase, was investigated. Two polymer blends prepared from a PTMO-based and a PEO-based polyurethane were also studied. Differential scanning calorimetry (DSC) and dynamic mechanical analysis indicated that the polyurethanes based on either the PEO or the PTMO soft segments are relatively phase mixed. The degree of phase mixing in the polymers increased with increasing weight fraction of PEO. As expected, water absorption and the hydrophilicity of the polymer increased with increasing PEO soft segment content. In vacuum, the PEO-rich polymers have a lower concentration of soft segment at the surface, possibly due to the migration of the polar PEO segments away from the pol...

Concentration dynamics in polymer blends and block copolymer melts

Abstract: Application de la theorie de la dynamique lente des concentrations de monomere dans des melanges de polymere en admettant un potentiel chimique constant pour la densite en monomere totale. Deduction d'equations de mouvement linearisees pour les variations de concentration a partir d'etats homogenes et d'un etat lamellaire a l'equilibre

Multilayered barrier structures for packaging

Abstract: Multilayered barrier film products providing gas and moisture barrier properties. The film products comprise at least a first polymer film having low permeability to moisture and a heterogeneous polymer blend film containing a gas barrier polymer and a second polymer distributed in the gas barrier polymer, so as to allow the heterogeneous polymer blend film to adhere to the first polymer film. A method for the preparation of multilayered barrier film products includes the steps of forming a gas barrier polymer film from a heterogeneous polymer blend containing a gas barrier polymer and a second polymer and, bonding a moisture barrier polymer film to at least one side of the gas barrier polymer film. The method can be practiced utilizing conventional coextrusion equipment.

Enthalpy relaxations in polymer blends and block copolymers: Influence of domain size

Abstract: It is now well known that enthalpy relaxation measurements can be used to establish polymer-polymer blend phase behavior when the glass transition temperatures of the two polymers are virtually coincident. In the most simple cases, the aging kinetics of an immiscible blend will be representative of the pure polymers superimposed upon each other. However, in many cases the situation is more complicated because of the presence of interface material. In this paper the relation between enthalpy recovery peak separation, domain size and interface thickness is considered. The discussion is based on relaxation experiments involving di-block copolymers of styrene and 2-vinyl pyridine, blends of polystyrene and poly(2-vinyl pyridine) and blends of poly(vinyl chloride) and poly(isopropyl methacrylate). If the amount of material in the interface is too large due to either a small average domain size or a thick interface no peak separation will occur. The first situation is found for the microphase separated block copolymer system whereas the second possibility occurs for blends of polymers which are on the verge of miscibility like poly(vinyl chloride) and poly(isopropyl methacrylate).

Polymer dispersed nematic liquid crystal films: The density ratio and polymer’s curing rate effects

Abstract: The effects of the density ratio and the polymer’s curing rate on the characteristics of polymer dispersed nematic liquid crystal (NLC) films are reported. Measurements indicated that the slope of the electro‐optical response curve, which determines the film’s multiplexing capability, is a strong function of the uniformity of the NLC droplet’s size. Both the density ratio and the polymer’s curing rate are shown to be crucial in the production of a more uniform droplet size. Polymer dispersed LC films, suitable for different applications, can be produced by varying the curing rate.

Thermodynamics of hydrogen bonding in polymer blends. 2. Phase behavior

Abstract: Expressions decrivant l'energie libre du melangeage de polymeres qui interreagissent par formation de liaisons hydrogenes

Controllable specific interaction and miscibility in polymer blends, 1. Hydrogen bonding and morphology

Abstract: This paper concentrates on the effect of introducing hydrogen bonding into otherwise immiscible blends on their miscibility and morphology. 1,1,1,3,3,3-Hexafluoro-2-hydroxypropyl-containing units are incorporated in polystyrene which is then mixed with carbonyl-containing polymers such as poly(methyl methacrylate) and poly(butyl acrylate). The infrared study confirms the formation of hydrogen bonding and shows that the frequency shifts of hydroxyl stretching caused by the H-bonds are independent on whether the hydroxyl-containing units are in the monomer or connected to polystyrene or polyisoprene chains and whether they are randomly distributed along the chains or only located at the ends of the polymers. Hydrogen bonding in the blends dramatically enhances miscibility judged by differential scanning calorimetry and transmission electron miscroscopy (TEM). TEM observations reveal apparent and regular variations of the morphology in the blends with the content of the hydroxyl-containing groups, which implies that the morphological features of the blends, such as size of the dispersed phase, or extent of interpenetrating between the components are controllable simply by changing the structure and/or amount of the introduced groups forming the specific interaction in the blends.

Critical wetting in two‐component polymer blends

Abstract: We derive the free energy of a bulk two‐component polymer blend in the presence of a planar surface, and use these results to map out the region of critical wetting in parameter space. Unlike previous investigations of wetting, our free energy has terms containing gradients of the composition profile at the surface, and we find that these terms have important consequences for critical wetting. In particular, the single gradient term causes the region of parameter space in which it is possible to find critical wetting to be greatly reduced. Although, as discussed in our concluding remarks, we find that the random phase approximation fails for a polymer blend near a surface, our conclusions concerning critical wetting are valid for a free energy which includes gradient terms of the general type considered here.

Basic functionalization of polyethylene in the melt

Abstract: The production of a polymer containing basic functional groups via the reactive processing of polyethylene was investigated. Grafting of dimethylamino ethyl methacrylate, DMAEMA, to linear low-density polyethylene in the melt was carried out, and the effects of initiator type, feed composition, and reaction time and temperature were studied. The extent of grafting was determined by Fourier transform infrared and 1H nuclear magnetic resonance spectroscopy, and the degree of cross-linking was observed by measuring the products' melt indices. Thermal stability of the product was investigated using differential scanning calorimetry. Materials containing up to 3 wt% of grafted DMAEMA were prepared. The choice of appropriate feed compositions and reaction conditions allows the production of a material containing the maximum amount of grafted DMAEMA, while minimizing cross-linking. The grafted polyethylene produced under these conditions is more stable than the starting material, suggesting an antioxidant effect of the grafted moieties. The functional polymer produced should be of interest for the preparation of polymer blends with acidic polymers by virtue of the miscibility enhancement that could occur as compared with the hydrocarbon precursor.

Ink composition containing a blend of a polyester, an acrylic polymer and a vinyl polymer

Abstract: Disclosed is a novel blend of a water-dissipatable polyester material, an acrylic polymer and a water-dissipatable vinyl polymer. The acrylic polymer and the vinyl polymer must be compatible with the polyester. The polyester is exemplified in having an acid component of from about 75 to about 84 mole % isophthalic acid and conversely from about 25 to about 16 mole % 5-sodiosulfoisophthalic acid, and having a glycol component of from about 45 to about 60 mole % diethylene glycol and conversely form about 55 to about 44 mole % 1,4-cyclohexanedimethanol or ethylene glycol or mixtures thereof. The polymer blends are useful for preparing ink compositions having improved block resistance, water resistance, and alcohol resistance.

Polymer blends with enhanced properties

Abstract: Polymer blends of a) polymers containing predominantly mers of (meth)acrylates and/or glutarimides with b) up to about 40 weight percent of polymers having greater than about 50 mol % vinyl alcohol mers exhibit useful barrier properties to oxygen and other environmental gases, while maintaining or enhancing physical properties and clarity.

Flame retardant ethylene polymer blends

Abstract: Wire insulation and cable jacketing compositions comprise blends of ethylene copolymers and propylene polymers.