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Showing papers on "Polymer blend published in 1992"


Journal ArticleDOI
15 Nov 1992-EPL
TL;DR: In this article, a new treatment of the phase behaviour of a colloid + nonadsorbing polymer mixture is described and calculated phase diagrams show marked polymer partitioning between coexisting phases, an effect not considered in the usual effective potential approaches to this problem.
Abstract: A new treatment of the phase behaviour of a colloid + nonadsorbing polymer mixture is described. The calculated phase diagrams show marked polymer partitioning between coexisting phases, an effect not considered in the usual effective-potential approaches to this problem. We also predict that under certain conditions an area of three-phase coexistence should appear in the phase diagram.

846 citations


Journal ArticleDOI
TL;DR: In this article, the electrical conductivity of carbon black (CB) filled polymer blends which are incompatible with each other was studied as a function of the polymer's blend ratio Transmission electron microscope (TEM) analysis shows that CB distributes unevenly in each component of a polymer blend.
Abstract: Electrical conductivity of carbon black (CB) filled polymer blends which are incompatible with each other was studied as a function of the polymer's blend ratio Transmission electron microscope (TEM) analysis shows that CB distributes unevenly in each component of a polymer blend TEM photographs of phase structure of solvent extracted HDPE/PMMA blend and solvent extraction experiments of PMMA/PP blend detect the blend ratio at which the structural continuity of filler rich phase is formed The electrical conductivity of polymer blends is found to be determined by two factors One is the concentration of CB in the filler rich phase and the other is the structural continuity of this phase This double percolation affects the conductivity of conductive particle filled polymer blends

318 citations


Journal ArticleDOI
TL;DR: In this article, a general expression for the time-correlation function of the polymer concentration around equilibrium and examine its relaxation in some typical cases is given, which can be used for gelling solutions and explains previous dynamic light scattering experiments at the sol-gel transition.
Abstract: Phenomenological hydrodynamic equations are proposed for entangled polymer blends as generalization of those for polymer solutions. They can describe coupling between macroscopic flow and relative diffusion. The key concept we use is the "tube velocity" introduced by Brochard in the problem of mutual diffusion in polymer blends. As applications, (I) we give a general expression for the time-correlation function of the polymer concentration around equilibrium and examine its relaxation in some typical cases. It can be strongly influenced by the viscoelastic effect when the two polymers have different lengths. Our expression can also be used for gelling solutions and explains previous dynamic light scattering experiments at the sol-gel transition. (ii) Detailed calculations are performed for the case of a single rheological relaxation time (the Maxwell model). The steady state structure factor is obtained to Iinear order in macroscopic flow. (iii) We predict that composition inhomogeneity is created in mixtures oflong and short polymers undergoing nonuniform flow. Its origin is that the longer chains support stress more than the shorter ones and the resultant imbalance of stress causes relative motion of the two polymers. These results are applicable both to solutions and blends.

308 citations


Journal ArticleDOI
01 Jan 1992-Polymer
TL;DR: In this article, the relationship between the miscibility and transesterification in the individual blend pairs is detailed in a review, including polyester liquid crystals, and a variety of polyester blends are discussed.

301 citations


Journal ArticleDOI
TL;DR: In this article, the evolution of phase morphology of polymer blends from pellets to submicron particles in a co-rotating twin-screw extruder was explained using scanning electron microscopy.
Abstract: The major morphological changes during polymer blending occur during the initial softening stage. This work explains the evolution of phase morphology of polymer blends from pellets to submicron particles in a co-rotating twin-screw extruder. The extruder was opened and blend samples were taken along its length. The major phase component was extracted by means of a selective solvent so that the dispersed phase morphology could be viewed directly by using scanning electron microscopy. The two systems studied were 80:20 polystyrene/amorphous polyamide and 80:20 polystyrene/polypropylene. In both systems, the initialmorphology consisted of sheets of dispersed phase

209 citations


Journal ArticleDOI
TL;DR: In this article, a review of a variety of reactive polymers used in the reactive compatibilization of polymer blends is presented, including maleic anhydride, carboxylic acid derivatives, primary and secondary amines, hydroxyl and epoxide.
Abstract: Blending of immiscible polymers offers attractive opportunities for developing new materials with useful combinations of properties. However, simple blends often have poor mechanical properties and unstable morphologies. Compatibilization of such blends is necessary. Preformed graft or block copolymers have been traditionally added to act as compatibilizers. Another route, however, is to generate these copolymer compatibilizers in situ during melt blending using functionalized polymers. In this review, a variety of reactive polymers that have been utilized in the reactive compatibilization of polymer blends is examined. They are classified into six major categories according to the types of reactive groups they have, namely, maleic anhydride, carboxylic acids, carboxylic acid derivatives, primary and secondary amines, hydroxyl and epoxide, and reactive groups capable of ionic bonding. Their preparation methods and applications and the chemical reactions they undergo during melt blending are presented. © 1992 John Wiley & Sons, Inc.

201 citations


Journal ArticleDOI
01 Jan 1992-Polymer
TL;DR: In this paper, a series of blends were prepared by adding a polyetherimide, in varying proportions, to a trifunctional epoxy resin, triglycidylparaaminophenol, cured with 4,4′-diaminodiphenylsulphone.

198 citations


Journal ArticleDOI
Ronald G. Larson1
TL;DR: In polymer solutions or blends, flow can strongly influence the degree of mixing of the components as mentioned in this paper, and it can induce ordering transitions in liquid crystals or block copolymers, which can also occur when the two components of the mixture differ greatly in viscoelastic properties.
Abstract: In polymer solutions or blends, flow can strongly influence the degree of mixing of the components. In a shearing flow, droplets in a dispersion can be broken down to sizes comparable to the dimensions of the polymer molecules themselves, thereby inducing molecular-scale mixing. Demixing can also occur when the two components of the mixture differ greatly in viscoelastic properties. Shear or extensional flow can induce polymer migration in nonhomogeneous flows or in flows with curved streamlines, and can render turbid solutions or blends that are otherwise transparent. Flow can also induce polymer gelation, and can induce ordering transitions in liquid crystals or block copolymers. Here, we review these phenomena, discuss proposed mechanisms, and assess the degree to which recent theories can account for the observations. Because the phenomena are complex, multiple experimental probes and theoretical methods are required to study them. Successful theories must incorporate polymer/polymer or polymer/solvent thermodynamics, critical phenomena, and phase transitions, as well as polymer theology and the kinetics of diffusion or crystallization. The experimental techniques used to study these phenomena are equally wide ranging, and include turbidity measurements, light, x-ray, and neutron scattering, fluorescence quenching, microscopy, and theology.

190 citations


Journal ArticleDOI
TL;DR: Spinodal decomposition in thin films of a blend of deuterated polystyrene and poly(styrene-co-4-bromostyrene) was studied with time-of-flight elastic-recoil detection and light microscopy and found different demixing behavior, depending on whether the films were prepared on the oxide layer of a silicon wafer or on a chromium-plated one.
Abstract: Spinodal decomposition in thin films of a blend of deuterated polystyrene and poly(styrene-co-4-bromostyrene) was studied with time-of-flight--elastic-recoil detection and light microscopy. We found different demixing behavior, depending on whether the films were prepared on the oxide layer of a silicon wafer or on a chromium-plated one. On the latter surface a bilayer of the two bulk phases is formed, whereas on the oxide layer a domain structure remains. The formation of the bilayer is ascribed to the complete wetting of each surface by the corresponding, preferentially adsorbed component.

171 citations


Journal ArticleDOI
01 Jan 1992-Polymer
TL;DR: In this article, the mechanical behavior and morphology of films prepared from poly(ethylene terephthalate), poly(butylene-terephthalates) and polyamide-6 blends subjected to zone drawing and annealing with fixed ends are studied.

168 citations


Journal ArticleDOI
Souheng Wu1
TL;DR: The intrinsic brittle-ductile (craze-yield) behavior of polymers and blends are controlled by two chain parameters: entanglement density ve and characteristic ratio Cx.
Abstract: The intrinsic brittle-ductile (craze-yield) behavior of polymers and blends are controlled by two chain parameters: entanglement density ve and characteristic ratio Cx. These chain parameters can be predicted from chemical structure. Therefore, the intrinsic brittle-ductile behavior of polymers and blends can be controlled by chemical structure using group additivity. The chemical composition and chain structure which can give the ultimate toughness in polymers and blends are discussed.

PatentDOI
TL;DR: In this paper, a series of azo polymers, copolymers and polymer blends for reversible optical storage devices are described, where the information can be erased thermally by heating above the glass transition temperature, or optically by overwriting with light polarized in a predefined zero direction or with circularly polarized light.
Abstract: A novel series of azo polymers, copolymers and polymer blends for reversible optical storage devices are described. Various azobenzenes can be bound in the side chain or within the main chain of long chain polymers such as polyester, polystyrene and poly methacrylates with very short or no spacers to a form amorphous polymers which as a film or deposited on a transparent substrate can be used to record optical information using a linearly polarized laser beam which induces optical anisotropy in the film. The information can be erased thermally by heating above the glass transition temperature, or optically by overwriting with light polarized in a predefined zero direction or with circularly polarized light.

Journal ArticleDOI
TL;DR: Elastic light scattering and optical microscopy were used to follow the phase separation after quenches into the coexistence region of the phase diagram.
Abstract: We present the method and results of two phase-separation experiments performed on the binary polymer blend polyisoprene-poly(ethylene propylene). Elastic light scattering and optical microscopy were used to follow the phase separation after quenches into the coexistence region of the phase diagram.

Journal ArticleDOI
TL;DR: In this article, the relaxation dynamics in miscible blends of PEO and PMMA ranging in composition from 20 to 60 wt% of PMMA were studied subsequent to a linear step strain using the simultaneous measurement of infrared dichroism and birefringence.
Abstract: Relaxation dynamics in miscible blends of PEO and PMMA ranging in composition from 20 to 60 wt% of PMMA are studied subsequent to a linear step strain using the simultaneous measurement of infrared dichroism and birefringence. From the temperature and composition dependences of component relaxation times it is clear that each component of the blend retains a separate rheological identity. Component relaxation dynamics shows a dramatic and complex sensitivity to blend composition. In PMMA-rich blends each component adopts a separate friction factor with a unique temperature dependence

Journal ArticleDOI
01 Jan 1992-Polymer
TL;DR: In this paper, the effect of shear flow on the phase behavior of partially miscible polymer blends exhibiting a lower critical solution temperature behavior was investigated, with and without the application of flow, using light scattering and as a shift in the glass transition temperature.



Patent
25 Jun 1992
TL;DR: In this article, a block copolymer having a polysiloxane block of the structure is defined, and a polycarbonate block and an aromatic carbonate polymer is presented.
Abstract: New thermoplastic blends are provided, comprising (A) a block copolymer having a polysiloxane block of the structure : where R¹, R², Y and D are as herein defined, and a polycarbonate block, and (B), an aromatic carbonate polymer. These blends have processing, low temperature impact strength and flammability advantages.

Journal ArticleDOI
01 Jan 1992-Polymer
TL;DR: In this article, the authors investigated the miscibility and domain structure of poly(vinyl alcohol)/poly (vinylpyrrolidone) (PVA/PVP) blends by high-resolution solid-state 13 C nuclear magnetic resonance methods.

Journal ArticleDOI
TL;DR: In this paper, the early stages of blend morphology development as occurs in a screw extruder were investigated using combinations of similar polymers (polystyrene and styrene-butadiene copolymer) and dissimilar polymers as model systems.
Abstract: This paper deals with the early stages of blend morphology development as occurs in a screw extruder. Using combinations of similar polymers (polystyrene and styrene-butadiene copolymer) and dissimilar polymers (PS and EVA) as model systems, it has been concluded that during melting the scale of segregation between the blend components is reduced by orders of magnitude within fraction of a second residence time. During the early stages of morphology development, the melting pellets produce fine lamellar structures (thickness of the order of μm) that extend over much of the melting zone before being broken up by capillary forces

Journal ArticleDOI
TL;DR: In this article, the effect of incident O2 + energy and angle on depth resolution and sputtering rate in polystyrene (PS) thin films was investigated using dynamic secondary ion mass spectrometry (SIMS).
Abstract: Dynamic secondary ion mass spectrometry (SIMS) has recently been employed to obtain high resolution depth profiles in polymer blend thin films and is now regarded as a key probe of surface and interfacial segregation in these systems. Segregation phenomena strongly impact blend properties such as adhesion, friction and weatherability. The strengths and limitations of the SIMS polymer profiling technique are described and contrasted with the complementary techniques of forward recoil elastic scattering (FRES) and neutron reflectivity (NR). The procedures developed for sample preparation and data acquisition are discussed. Experimental results for the effect of incident O2 + energy and angle on depth resolution and sputtering rate in polystyrene (PS) are presented. Ongoing SIMS studies of model blend systems are described: Segregation from dPS (deuterated)/PS blends to vacuum and Si interfaces is examined as a function of the molecular weight of the blend components and preparation of the Si substrate, reve...

Patent
12 May 1992
TL;DR: In this paper, an esterification reaction takes place between the maleic anhydride groups in the copolymer with free hydroxyl groups in starch according to the general reaction process.
Abstract: In order to produce a polymer mixture essentially consisting of starch and a polyolefine, up to 70 wt %. of thermoplastically processable starch is mixed with 10 to 40 wt %. polyolefine and 10 to 35 wt %. ethylene acrylate maleic anhydride copolymer. During this mixing process an esterification reaction takes place between the maleic anhydride groups in the copolymer with free hydroxyl groups in the starch according to the general reaction process (I).

Patent
16 Nov 1992
TL;DR: In this paper, a biodegradable mold material or polymer blend with a high resistance to moisture is obtained by mixing thermoplastically processable starch with a cellulose derivative, such as cellulose ester.
Abstract: A biodegradable mould material or polymer blend with a high resistance to moisture is obtained by mixing thermoplastically processable starch with a cellulose derivative, such as a cellulose ester.

Journal ArticleDOI
TL;DR: In this article, the viscosity of Vectra A900, a thermotropic liquid crystalline polymer (LCP), and poly(ethylene terephthalate) (PET) was studied over the entire composition range using scanning electron microscopy, differential scanning calorimetry, and rotational rheometry.
Abstract: Blends of Vectra A900, a thermotropic liquid crystalline polymer (LCP), and poly(ethylene terephthalate) (PET) were studied over the entire composition range using scanning electron microscopy, differential scanning calorimetry, and rotational rheometry. There is some interaction between the polymers, as evidenced by melting‐ and crystallization‐point depression in the PET phase. The shear rheology deviates substantially from simple mixing laws and from predictions of an emulsion model of dispersed blends. The viscosity of LCP‐rich compositions exceeds that of either component at low rates and frequencies. The viscosity of PET‐rich compositions falls below that of either component at low rates and frequencies. The latter observation cannot be explained by deformation and orientation of the LCP phase, since the dispersed LCP inclusions remain spherical following steady shear.

Patent
16 Sep 1992
TL;DR: Blended polymer compositions are described in this article, which comprise (I) from about 1% to about 97% by weight of at least one alpha-olefin polymer, (II) from approximately 0.1% to 0.2% of a polyamide, and (III) an effective amount of a mixture of two or more compatibilizing agents selected from the group consisting of (IVa) at least hydrogenated block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene to which has been grafted, (IVb)
Abstract: Blended polymer compositions are described which comprise (I) from about 1% to about 97% by weight of at least one alpha-olefin polymer; (II) from about 1% to about 97% by weight of at least one polyamide; (III) from about 1% to about 97% by weight of at least one polymer of a vinyl aromatic hydrocarbon; and (IV) an effective amount of a mixture of two or more compatibilizing agents selected from the group consisting of (IVa) at least one selectively hydrogenated block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene; (IVb) at least one selectively hydrogenated block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene to which has been grafted, an alpha,beta-olefinically unsaturated monocarboxylic or dicarboxylic acid reagent; and (IVc) at least one terpolymer of an alpha-olefin, at least one acrylic ester, and an alpha,beta-olefinically unsaturated dicarboxylic acid reagent, or a glycidyl acrylate. The polymer blends of the present invention have improved impact-resistance.

Journal ArticleDOI
TL;DR: In this article, two polymer blend systems were studied: the poly (acrylonitrile) (PAN)-poly (styrene sulfonic acid) (PSSA) and the polyvinyl alcohol (PVA)-PSSA blend.

Journal ArticleDOI
TL;DR: In this paper, an equation based on the crowding factor of concentrated suspension rheology and Janzen's particle contacts percolation is proposed to describe the relationship between ϕc, and the maximum packing fraction of conductive fillers.
Abstract: Increasing utilization of the electrical properties of polymeric blends and composites has prompted our renewed interest in developing a general working relationship which can explain the electrical properties of polymer composites and blends in terms of processing characteristics, morphology, and compositions. Here, we restrict our attention to the following two-component systems: (1) two component systems with conductive particulate inclusions (e.g. carbon black) embedded in a continuous polymeric matrix, and (2) two component polymer blend systems with one conductive polymer (e.g., polyether copolymer) dispersed in another continuous polymeric matrix. The following processing aspects related to the electrical property of particulate filled composites are discussed: (1) critical concentration of rigid conductive fillers, ϕc, and (2) redistribution of conductive fillers upon processing. An equation based on the crowding factor of concentrated suspension rheology and Janzen's particle contacts percolation is proposed to describe the relationship between ϕc, and the maximum packing fraction of conductive fillers. The relationship is used to explain the influence of particle morphology on conductivity, and the conductivity difference in the high shear and the low shear region of a processed polymer composite part. Furthermore, some qualitative guidelines for blending a low conductivity polyether copolymer to achieve an overall balance of antistatic and mechanical properties of polymer blends are also discussed.

Patent
24 Feb 1992
TL;DR: In this article, a process for producing a bimodal ethylene polymer blend comprising contacting in a first gas phase, fluidized bed reaction zone under polymerization conditions, a gaseous monomeric composition comprising a major proportion of ethylene and, optionally, hydrogen, with a Ziegler-Natta catalyst, was provided.
Abstract: A process is provided for producing a bimodal ethylene polymer blend comprising contacting in a first gas phase, fluidized bed reaction zone under polymerization conditions, a gaseous monomeric composition comprising a major proportion of ethylene and, optionally, hydrogen, with a Ziegler-Natta catalyst, the hydrogen/ethylene molar ratio (H₂/C₂ ratio) being no higher than about 0.3 and the ethylene partial pressure being no higher than about 100 psia, to produce a relatively high molecular weight (HMW) polymer associated with catalyst particles, transferring the HMW polymer associated with catalyst particles to a second gas phase, fluidized bed reaction zone into which is also fed hydrogen and a gaseous monomeric composition comprising a major proportion of ethylene, under polymerization conditions including an H₂/C₂ ratio of at least about 0.9 and at least about 8.0 times that in the first reaction zone, and an ethylene partial pressure of at least 1.7 times that in said first reaction zone, to produce a low molecular weight (LMW) polymer deposited on and within the voids of the HMW polymer/catalyst particles, the resulting bimodal polymer blend obtained from the second reaction zone having a fraction of HMW polymer of at least about 0.35.

Patent
06 Oct 1992
TL;DR: In this paper, an anisotropic oriented sheet excellent in temperature dependency by using a polymer obtained by blending a polymer having a high temperature dependency of retardation with a resin having a low temperature dependency, or a laminated body thereof is presented.
Abstract: PURPOSE:To provide an anisotropically oriented sheet excellent in temperature dependency by using a polymer obtained by blending a resin having a high temperature dependency of retardation with a resin having a low temperature dependency, or a laminated body thereof. CONSTITUTION:One or a plurality of drawn and oriented transparent thermoplastic resin sheets are used. In this case, the value of retardation in visual light area is within the range of 100 to 1000nm, and the temperature change ratio is -0.4 to -2.5nm/ deg.C. The difference with the temperature change ratio of retardation of a liquid crystal to be compensated is within 15%. Further, the transparent thermoplastic resin is a transparent thermoplastic resin in which the full beam transmissivity in the form of sheet is 80% or more, which is a polymer blend, copolymer, craft polymer, or laminated body consisting of a non-crystalline thermoplastic resin or a transparent crystalline resin whose crystal grain is smaller than visual lights. The retardation value is measured by polarization interference.

Patent
James S. Mrozinski1
24 Feb 1992
TL;DR: In this paper, a method for preparing a microporous polyolefin shaped article which includes the steps of melting blending polyolefins with an additive which is miscible with the polymer at the melt temperature of the blend but which phase separates on cooling to form a solution is presented.
Abstract: A method for preparing a microporous polyolefin shaped article which includes the steps of (1) melt blending a polyolefin with an additive which is miscible with the polymer at the melt temperature of the blend but which phase separates on cooling to form a solution; (2) forming a shaped article from the solution; (3) cooling the shaped article by use of a patterned chill roll to provide areas on the surface of the article where the polymer mixture does not contact the chill roll; and (4) (a) removing at least a substantial portion of the compatible liquid; or (b) stretching the article in at least one direction sufficient to permanently attenuate the article and effect orientation of the polymer; or (c) a combination of (a) and (b) to form a microporous polyolefin shaped article. The article is of substantially uniform thickness and has a patterned surface. The patterned surface provides substantially skinless areas having high microporosity and skinned areas or reduced porosity.