Showing papers on "Polymer blend published in 1987"

The morphology and rheology of polymer blends containing a liquid crystalline copolyester

Abstract: The morphology of blends of polycarbonate and nylon 6,6 with a copolyester of 60 mole percent p-hydroxybenzoic acid/40 mole percent poly(ethylene terephthalate) was characterized under different processing conditions. In particular, single-screw extrusion, steady simple shear flow, and flow through a capillary were studied to determine what conditions were necessary for the development of a fibrillar morphology of the liquid crystalline polymer (LCP). Results indicate that some extensional flow is required for the coalescence and extension of the particulate LCP phase. The viscosity of the blends was determined both in a cone-and-plate geometry of a Rheometrics Mechanical Spectrometer at low shear rates and in the Instron Capillary Rheometer at higher rates. In general, only a small (10 or 30 percent) weight fraction of LCP was required to reduce the viscosity of the thermoplastics to that of the polymeric liquid crystal. An attempt was made to correlate the structure of the blends seen under the scanning electron microscope with the observed rheology. Not all aspects of the morphology were possible to explain in terms of the viscous properties of the blends.

Layered surgical biocomposite material

Abstract: Biocomposite material that is especially suitable for bone surgical applications, containing: at least one bioceramic piece (1) (bioceramic component) and at least one material component (2). The material component (2) comprises at least reinforcement elements which have been manufactured of essentially resorbable material like polymer, copolymer, polymer mixture and/or ceramic material.

Electrophotographic carrier particles coated with polymer mixture

Abstract: Disclosed is a carrier and developer composition, and a process for the preparation of carrier particles with substantially stable conductivity parameters which comprises (1) providing carrier cores and a polymer mixture; (2) dry mixing the cores and the polymer mixture; (3) heating the carrier core particles and polymer mixture, whereby the polymer mixture melts and fuses to the carrier core particles; and (4) thereafter cooling the resulting coated carrier particles.

Laminar morphology in polymer blends: Structure and properties

Abstract: Polymer-polymer blends offer a route for enhancement of various properties. When immiscible polymers are blended together (in the presence of a compatibilizer), the blend properties are dependent on the morphology of the phases. Uniform, fine dispersions generally result in “average” properties. Discussed here are blends of polyamides or polyesters with polyolefins, particularly polyethylene, where small amounts (3–20 percent) of the former polymers dispersed as essentially parallel, thin, large laminae produce substantial reduction (3–100 times) of permeability properties in blow-molded/extruded articles. Physical properties of such blends, their permeability properties, and morphologies are discussed.

Mean-field and Ising critical behavior of a polymer blend.

Abstract: The critical fluctuations of a polymer blend (PVME/d-PS) were investigated by neutron small angle scattering. A mean-field behavior was observed, except in a region very close to the critical temperature where a transition to an Ising-like behavior occurs. The width of this region is T-${\mathrm{T}}_{\mathrm{c}}$\ensuremath{\simeq}2.4 K for a mixture with average molecular weights of 89 000 (PVME) and 232 000 (d-PS).

Characterization and control of interfaces in emulsified incompatible polymer blends

Abstract: Information on the interfacial region in incompatible polymer mixtures can be gathered using various techniques including electron microscopy, thermal transition analysis, and more sophisticated methods such as nonradiative energy transfer (NRET). Selected examples are reported here to illustrate the exciting potentialities offered by diblock copolymer emulsifiers in controlling interfacial adhesion and devising high performance polymer blends.

Polystyrene-polyethylene melt blends obtained through reactive mixing process

Abstract: Reactive polystyrene (OPS) and reactive polyethylene (CPE) with oxazoline and carboxylic acid functionality, respectively, were melt blended in a Rheomix mixer under a variety of conditions. The properties of these blends were examined and correlated with the compositions and mixing conditions such as shear rate, time, and temperature. An increase in torque was observed, which is believed related to chemical reaction between OPS and CPE. The difference between the maximum and minimum torque (Tmax-Tmin), increases from 48 to a maximum of 510 m-g for 10 and 40% CPE reacted blends, respectively, But on further increase in the CPE amount in the blend the torque increase drops reaching a final minimum value of 133 m-g for a blend with 90% CPE. Differential Scanning Calorimetry (DSC) studies reveal a single first order transition, due to CPE, for each of these polymer blends. Furthermore, evidence of the glass transition temperature for OPS diminishes with increasing CPE content and mixing time. Scanning Electron Micrographs (SEM) show a fine dispersion in these reactive blends, with particle size much smaller than a micron. Blends with 50% or more CPE have no distinguishable features as such. Mechanical properties such as elongation at break of reacted blends are improved over the nonreactive polyethylene (PE) and polystyrene (PS) blends. An intermolecular reaction between the OPS and CPE results in a graft polymer, which imparts improvement in the overall properties of these reacted blends. The maximum grafting reaction corresponds to 40% CPE blend, which is being evaluated as a potential compatibilizer.

Particulate polymer composition, a method of making particulate polymer compositions, and light-scattering thermoplastic polymer compositions containing the particulate polymers

Abstract: A particulate polymer composition comprising core/shell polymer particles in a size range between 2 and 15 micrometers, and having a core with a refractive index close to, but not identical with, that of a matrix polymer and an outer shell compatible with the matrix polymer, imparts light-diffusing properties to the matrix polymer without degrading its physical properties

Polymer surfaces and interfaces

Abstract: Application of Ellipsometry to Polymers at Interfaces and in Thin Films (D. Styrkas, et al.). MeV Ion Beam Profiling of Polymer Surfaces and Interfaces (M. Geoghegan). Phase Separation in Thin Films of Strongly Incompatible Polymer Blends (S. Walheim, et al.). Mechanical Properties of Polymer Interfaces (C. Creton). Neutron Reflectivity for the Study of Polymer Interfaces (R. Jones). Modification of Electrode Surfaces with Electroactive Polymers (A. Hillman, et al.). Interactions of Tethered Polyelectrolytes in Poor Solvents (C. Singh, et al.). Viscoelastic Properties of Polymer Films from Surface Quasi--Elastic Light Scattering (S. Peace & M. Taylor). Magnetic Resonance Relaxation and Imaging (P. McDonald & D. Lane). Surface Modification for Adhesion Minimization in Aqueous Environments (W.--L. Chen & K. Shull). Atmospheric versus Low--Pressure Plasma Oxidation of Rubber Surfaces (S. Wheale, et al.). Index.

Quantitative small-angle light-scattering studies of the melting and crystallization of LLDPE/LDPE blends

Abstract: Small-angle light-scattering (SALS) patterns were obtained during melting and crystallization of blends of linear low-density polyethylene (LLDPE) with conventional low-density polyethylene (LDPE) Quantitative measurements of these SALS patterns using a two-dimensional optical multichannel analyzer apparatus (OMA2) indicate that the LLDPE which is miscible with the LDPE component in the molten state crystallizes first, forming volume-filling spherulites The LDPE then crystallizes within the preformed spherulites These findings are supported by optical microscopy studies showing that the blend samples were volume filled with one kind of the spherulites having a radius comparable to that of the pure LLDPE The SALS intensity curve changes with composition of the blends in a manner that may be interpreted by considering the orientation of crystals within spherulites It has been observed that the spherulites in the blend have more diffuse boundaries as the LDPE content increases The lattice spacing and long spacings in blends were obtained by wide-angle and small-angle x-ray scattering, respectively The SALS technique along with differential scanning calorimetry (DSC) is shown to be useful for determining the crystallization behavior of a crystallizable polymer blend system

Fast macromolecules control mutual diffusion in polymer blends

Abstract: The tracer diffusion coefficient D* of small concentrations of tagged linear polymers seems well understood on the basis of the reptation model1–6, but the mutual diffusion coefficient D which characterizes diffusion at higher concentrations remains controversial7–17. Such diffusion is important in blends of miscible, yet chemically dissimilar, polymers where it controls the kinetics of phase separation and the welding of polymer interfaces. The controversy centres on predicting D from the D*s of the components of the blend. While the 'slow theory'7,8 predicts that D is controlled by the diffusion of the slower-moving component, 'fast theory'9,10 says it is controlled by the diffusion of the faster-moving one. Here we report experiments in which we measure the mutual diffusion coefficient as we increase the tracer diffusion coefficient of the faster-moving component in the blend by decreasing its molecular weight. The strong increase in D we observe demonstrates that the 'fast theory' prediction is correct.

Rheological behavior of compatible polymer blends. I. Blends of poly(styrene-Co-acrylonitrile) and poly(ε-caprolactone)

Abstract: The rheological behavior of blends of poly(styrene-co-acrylonitrile) (SAN) and poly(e-caprolactone) (PCL) was investigated, using a cone-and-plate rheometer. For the study, blends of various compositions were prepared by melt blending using a twin-screw compounding machine. The rheological properties measured were shear stress (σ12), viscosity (η), and first normal stress difference (N1) as functions of shear rate (γ) in steady shearing flow, and dynamic storage modulus (G′) and loss modulus (G″) as functions of angular frequency (ω) in oscillatory shearing flow, at various temperatures. It has been found that logarithmic plots of N1 versus σ12, and logarithmic plots of G′ versus G″, become virtually independent of temperature but vary regularly with blend composition, and that the zero-shear viscosity of the blends, (ηo)blend, follows the relationship, 1/log(ηo)blend = wA/log η0A + wB/log η0B, where η0A and η0B are the zero-shear viscosities of components A and B, respectively, and wA and wB are the weight fractions of components A and B, respectively. The physical implications of the relationship found are discussed.

Kinetics of phase separation in polymer mixtures

Abstract: Characteristic features of the liquid-liquid phase separation process in polymer systems are presented, followed by a concise review of existing studies on phase-separation kinetics in polymer solutions and mixtures. Brief discussions have been made on two selective topics in this field, i.e., applicability of Cahn's linearized theory for spinodal decomposition to polymer mixtures and the scaling law in the late stage of phase separation.

Polycarbonate-siloxane polyetherimide copolymer blends

Abstract: A polymer blend containing a polycarbonate and a siloxane-polyetherimide copolymer. The blends of the invention have improved impact strength, particularly thick section impact strength, over the unmodified polycarbonates. In addition the blends have good physical properties, relatively low flammability and are resistant to environmental stress cracking and crazing.

Blue-colored bioabsorbable surgical fibers and production process thereof

Abstract: Blue-colored bioabsorbable surgical fibers are obtained by adding and dispersing a bioabsorbable polymer, which is selected from polyglycolic acid, poly(l-lactic acid) and glycolic acid-l-lactic acid copolymers all of which are useful as surgical fibers, and indigo in a non-aqueous organic solvent having low solubility for the polymer and indigo, heating the resultant dispersion at a temperature below 120° C. to distill off the solvent, thereby to obtain a master batch with the indigo incorporated therein at a high concentration, mixing and kneading the master batch with a fresh supply of the polymer, and then spinning the resultant polymer mixture.

Laminates containing coextruded scrap.

Abstract: A continuous plastic laminate having improved stiffness at use temperature, comprising at least three melt coextruded sheets, each comprising a thermoplastic polymer or polymer blend, the outside sheets having a higher stiffness at use temperature than at least one inside sheet, wherein said continuous laminate contains laminate scrap derived from the production of said laminate, said scrap being incorporated therein by melt coextruding said scrap as at least one additional discrete inside layer or by melt coextruding said scrap as part of at least one of said melt coextruded sheets, whereby the stiffness at use temperature of said scrap-containing laminate is increased relative to a plastic laminate identical thereto except for the incorporation of said scrap, and wherein said thermoplastic polymer or polymer blend comprises a polyarylether sulfone, a poly(aryl ether), a polyarylate, a polyetherimide, a polyester, an aromatic polycarbonate, a styrene resin, a poly(alkyl acrylate), a polyhydroxyether, a polyamide, a poly(arylene sulfide), a crystalline polyolefin, a polyphenylene oxide, or blends thereof.

Phase Relations and Miscibility in Polymer Blends Containing Copolymers.

Abstract: This article reviews the reported work on thermodynamics of polymer blends in which at least one of the components is a copolymer. Theoretical and experimental studies of miscibility and phase transition and separation behaviors in such systems are summarized. Chapter 2 deals with blends involving random copolymers, including the cases in which a random copolymer AB is mixed with either a homopolymer A, or a homopolymer C, or two homopolymers A and B. Chapter 3 deals with blends involving a block copolymer, and after giving a brief overview of systems containing a pure block copolymer alone, it reviews the blend systems containing a block copolymer AB mixed with a homopolymer A or two homopolymers A and B.

The importance of enthalpic interactions in polymeric systems

Abstract: Enthalpic interactions between blend components primarily determine the state of miscibility and many of the physical properties of the blend. Recent applications of these thermodynamic considerations are reviewed for a variety of systems, including binary and ternary blends of homopolymers, binary blends of copolymers with homopolymers, and polymer-solvent mixtures. Recent advances toward predicting polymer blend miscibility through use of a modified quasichemical thermodynamic model and heats of mixing data for liquids are also discussed.

Compatible polymer blends

Abstract: The invention relates to compatible polymer blends comprised of a polymer component containing cyclohexyl (meth)acrylate as a monomer, and further comprised of a polymer component containing styrene as a monomer.

Properties of polycarbonate/acrylonitrile-butadiene-styrene blends

Abstract: To help make a good polymer blend by melt blending, the properties of polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) systems with various compositions have been investigated. As ABS is blended into PC to form a binary system, Brabender torque is reduced, a phenomenon that results in Improved processability of PC. With increasing ABS content, the mechanical properties of the blends such as tensile strength, modulus, hardness, and shrinkage decrease. However, with the variation of composition, Izod impact strength shows a maximum, while elongation at break exhibits a minimum. These phenomena are discussed with dynamic viscoelasticities and scanning electron microscopic morphological results. The value of ΔTg(TgβPC − TgβABS) is at its smallest when the ratio of PC to ABS is 90:10, However, the value rises with an increase in ABS because the butadiene content of the ABS hinders compatibility in the binary system. At the 90:10 composition, the damping height is optimal. In addition, the dispersed phase of the ABS is most ideal, absorbing the impact force and showing high impact strength. Composition ratios other than 90:10 present high damping as well as undesirable phase separation because of poor adhesion between two phases. As a result, the mechanical properties are reduced.

Dynamical theory of polymer melt morphology

Abstract: A general kinetic equation of the monomer density variables for polymer blends and block copolymer melts is obtained which describes slow morphology variations. The general theory is applied to a polymer blend adopting the biased reptation model of a polymer chain under mean field. We obtain an equation of motion of interfaces in a phase-separated polymer blend, which contains an interface reaction term for length scales shorter than lc ≡ R2G/ξ, where RG is the gyration radius of a polymer chain and ξ the interfacial width. We also discuss some problems associated with the incompressibility requirement for phase separation kinetics of binary systems not limited to polymers. For length scales greater than lc the interface dynamics involves diffusion in bulk pure phases even in the strong segregation limit in a way different from that for the usual time-dependent Ginzburg-Landau equation for the conserved order parameter. Implications of the existence of the new term on the late stage phase separation kinetics of polymer blend are discussed. A phenomenological model to study morphology dynamics not relying on the reptation model is also proposed.

Preparation of asymmetric membranes by the solvent extraction of polymer components from polymer blends

Abstract: Asymmetric membranes are prepared by selectively treating a major surface of an incompatible polymer blend prepared by melt blending having at least one extractable polymer component and then contacting the polymer blend with a solvent to extract the extractable polymer component. The treated surface becomes the dense layer of the membrane. The major surface is treated by crosslinking, by contacting the surface with a crosslinking agent which is subsequently cured, or by contacting the surface with an agent which reacts with groups on the surface and imparts a polar character to it.

Pressure-sensitive adhesives based on similar polymers

Abstract: A pressure-sensitive adhesive is formed from a high-molecular-weight polymer and is plasticized by a low-molecular-weight polymer, which polymers have monomer contents which differ by no more than 3 percent by weight.

Intermolecular polarization transfer study of polymer blend compatibility

Abstract: Methode d'etude du melangeage intermoleculaire dans les systemes multicomposants en utilisant la spectroscopie RMN a polarisation croisee et rotation de l'angle magique

Method of recording information and information recording medium employed for the same

Abstract: A method of recording information comprising the steps of: irradiating a light-absorbing material (which is arranged in contact with a polymer blend which changes in its phase condition between a homogeneous state and a phase-separated state in response to change of its temperature across its cloud point) with a laser beam for causing the light-absorbing material to absorb energy of the beam and generate a heat, whereby elevating the temperature of the polymer blend near the light-absorbing material to a temperature of above the cloud point to change the phase condition of the polymer blend into a state which is different from the original state before the elevation of the temperature; and rapidly cooling the polymer blend to fix the polymer blend in its changed phase condition. An information recording medium preferably employed for the method is also disclosed.

Ink-jet ink for plain paper printing

Abstract: An ink composition is provided for an ink-jet printer, preferably a thermal ink-jet printer. The composition comprises about 5 to 40 wt % glycol, about 60 to 90 wt % water, about 0.001 to 10 wt % polymer blend and about 1 to 7 wt % dye. The polymer blend includes both uncharged and charged monomeric units. The glycol and polymer blend act to form a soft plug that forms in the orifice of the ink-jet pen. The soft plug prevents further evaporaion of water, but unlike a hard plug, is readily blown out upon firing. The charged units in the polymer blend contribute to water fastness and light fastness of the dye on paper. Further, by employing appropriate functional groups in the polymer blend, chemical degradation of the ink dye can be retarded on acid or alkaline papers.