Showing papers on "Polymer blend published in 1993"

Linear viscoelastic behavior of some incompatible polymer blends in the melt. Interpretation of data with a model of emulsion of viscoelastic liquids

Abstract: The linear viscoelastic behavior of two-phase polymer blends in the melt has been analyzed by an emulsion model, with takes into account the viscoelasticity of the phases. In this paper, we have studied two types of blends: PS/PMMA and PDMS/POE-DO. For PS/PMMA blends, the model leads to values of relaxation times and secondary plateau modulus in accordance with experimental data. This supports the assumption that long-time relaxation mechanisms are due to geometrical relaxation of the droplets of the dispersed phase. For a quantitative comparison, further experiments have been carried out on PDMS/POE-DO blends for which the distribution of size of the dispersed POE-DO inclusions may be easily determined. The data confirm the validity of the model and show that dynamic shear measurements can be used as a method to determine the interfacial tension between two polymer melts. © 1993, American Chemical Society. All rights reserved.

Polymer Blends and Alloys

Abstract: Overview. Rheology of two-phase blends. Practical aspects of processing of blends. Compatibilization and reactive blending. Practical techniques for studying blend microstructure. Modelling the properties of polymer blends. Toughened polymers. Blends containing liquid crystal polymers. Fibre forming blends and in situ fibre composites. References. Index.

Ethylene-vinyl acetate (EVA) copolymers: a general review

Abstract: Ethylene-vinyl acetate (EVA) copolymers are used extensively in the wire and cable industry for making heat shrinkable insulation, semi-conductive insulation jackets, and flame retardant insulation. A general review of EVA copolymers is given. The following items are reviewed: EVA copolymer development, methods of manufacture, fundamental structural attributes, typical properties, processing and applications. >

Compatibilizing agents in polymer blends : interfacial tension, phase morphology, and mechanical properties

Abstract: The interfacial tension, phase morphology, and phase growth was determined for four polymer blend systems: polyethylene/polystyrene, polyethylene/polyamide-6, polystyrene/polyamide-6, and polystyrene/poly(ethylene terephthalate). Generally, high interfacial tension correlates with coarse phase morphology and rapid phase coalescence. The addition of various potential compatibilizing agents to these binary blend systems results in lowered interfacial tension, finer and stabilized phase morphologies. The characteristics of different compatibilizing agents were compared for several of the blend systems. We also look at the influences of compatibilizing agents on mechanical properties of the blend systems. Some compatibilizing agents are able to produce substantial improvements in ultimate properties.

Plastic knee femoral implants

Abstract: A knee prosthesis includes plastic femoral and metallic (or ceramic) tibial components. The plastic femoral knee component articulates against a polished metal (e.g. cobalt alloy, titanium alloy, or stainless steel), or preferably ceramic (e.g. alumina, zirconia, nitride, or boride) patella and tibial components in a total knee implant. The polymer femoral material can be of a polymer such as ultra high molecular weight polyethylene, or a polymer blend or a fiber or particle reinforced polymer, or layered polymers.

Elastomer Technology Handbook

Abstract: Analytical Test Methods for Polymer Characterization (N.P. Cheremisinoff, R. Boyko, and L. Leidy). Chemical Characterization in Polymer Analysis (A.B. Hunter). The Use of Thermal Analysis in Polymer Characterization (M.P. Sepe). Tensile Yield in Polymers (D. Hartmann and D. Sudduth). Mechanochemistry of Polymers Deformation and Fracture Processes (C.V. Oprea and M. Popa). Morphology and Mechanical Properties of Natural Rubber/Polyolefin Blends (J. Sunder). Properties Modelling of Viscoelastic Elastomers (H. So and U.-D. Chen). Interpenetrating Polymer Networks (D. Klempner and D. Sophiea). Catalysts for the Copolymerization of Ethylene-Propylene Elastomers (K. Makino). Thermal and Oxidative Stability of Ethylene-Propylene Rubber (G. Mares and P. Budrugeac). The Nature of Sulfur Vulcanization (M.R. Krejsa and J.L. Koenig). Peroxide Crosslinking of EPDM Rubbers (W.C. Endstra and C.T.J. Wreesmann). Properties and Degradation of Nitrile Rubber (S. Bhattacharjee, A.K. Bhowmick, and B.N. Avasthi). Thermoplastic Elastomers: A Rising Star (M.T. Payne and C.P. Rader). Markets for Thermoplastic Elastomers (R.J. School). Degassing of Thermoplastics during Extrusion with Single-Screw and Co-Rotating Twin-Screw Extruders (G. Martin and W. Schuler). Epoxidized Rubbers (S. Roy, B.R. Gupta, and S.K. De). Toughening Concept in Rubber-Modified High Performance Epoxies (H.-J. Sue, E.I. Garcia-Meitin, and D.M. Pickelman). Characterization of Phase Behavior in Polymer Blends (T. Ougizawa and T. Inoue). Compatibilization of Polymer Blends (R.L. Markham). Rubber Mixing Principles (N.P. Cheremisinoff). Rubber Extrusion Principles (N.P. Cheremisinoff). Blown Film Technology (J.D. Culter). Principles of Adhesive Rheology (F.M. Chen). Adhesion between Components of Elastomeric Composite Materials (Y. Kubo). Polymer Applications in the Construction Industry (R. Hussein and N.P. Cheremisinoff). Polymers in Sandwich Construction (R. Hussein). Polymer-Concrete Composites (R. Hussein). Properties of Polymers Suitable for Solar Energy Applications (R. Hussein). Appendices. Index.

The Interfacial interactions in polymeric composites

Abstract: Interfaces, interphases and "adhesion" - a perspective aspects of component interactions in polymer systems rheology at interfaces interactions and properties of composites - fibre-matrix adhesion measurements, adhesion composite properties relationships the role of interface at the wall in flow of concentrated composites application of surface analysis to high performance polimeric adhesives and composites some experimental methods of characterizing surface controlled interphases in glass fibre and particulate reinforced polymers - structure of silane coupling agents in solutions and on substrates control and modification of surfaces and interfaces by corona and low pressure plasma plasmas and surfaces - a practical approach to good composites plasma polimerification of acetylene - a coating technique for fibre reinforcement of composites plasma enhanced CVD of aromatics - surface treatment of carbon fibres to optimize fibre-matrix adhesion some notes on surface modification by plasma science and technology of polymer composites reinforcing fibres for composites "in situ" composites formed with polymers and thermoplastic matrices some short communications of participants - open questions on effects of fibre-matrix interactions on compound and composite properties, interface stabilization in polymer blends by means of block and graft copolymers, interfacial chemical interactions in condensation polymers and their blends, interfacial polarization and its diagnostic significance in polymeric composites, on the physical nature of interfacial layer in polymer coatings, the effect of corona modification on the composite interfaces, peculiarity of film-forming and hydrolytic decay of tin-containing polymer coatings, diffusion of metal ions in caroxylic polymer sorbents of different morphological structure, adsorption of methylene blue on PVC-DOP-natural zeolite composites, optically transparent glass fibre reinforced poly(methylmethacrylate) laminates, the effect of recycling on the properties of thermoplastic composites, carbon fibres from methane.

Factors influencing the formation of elongated morphologies in immiscible polymer blends during melt processing

Abstract: The morphology of the dispersed phase in immiscible polymer blends plays an important role in the determination of the final physical properties. This paper considers factors that influence the final state of deformation of the dispersed phase, and in particular, the formation of fibers and lamellae. Blends of polyethylene and nylon-6 were extruded by ribbon extrusion at different draw ratios. Prior to single-screw extrusion the materials were blended in a co-rotating twin-screw extruder, and the size of the dispersed phase was studied as a function of the viscosity ratio. As the blends are extruded into ribbons and drawn through the calender rolls, the morphology of the dispersed phase undergoes drastic transformations. The fiber formation is enhanced by increasing the draw ratio. At high draw ratios, long thin fibers are observed. Some biaxial deformation is obtained for the noncompatibilized systems when the extruded materials enter the calender with the maximum closing pressure applied to the rolls. The same effect is observed for the compatibilized systems with lower values of the viscosity ratio. As a general rule, it has been observed that the final dispersed phase deformation is diminished in interfacially compatibilized systems.

Polymer alloys based on poly(2,6-dimethyl-1,4-phenylene ether) and poly(styrene-co-acrylonitrile) using poly(styrene-b-(ethylene-co-butylene)-b-methyl methacrylate) triblock copolymers as compatibilizers

Abstract: Poly(styrene-b-(ethylene-co-butylene)-b-methyl methacrylate) (P(S-b-EB-b-MMA) triblock copolymers containing various amounts of the elastomeric center block (6-38 wt% PEB) have been used to compatibilize polymer blends based on poly(2,6-dimethyl-1,4-phenylene ether) (PPE) and poly(styrene-co-acrylonitrile) (PSAN). From the dynamic mechanical analysis and TEM, detailed information about the location of the block copolymers is obtained, because the intermixing of the PS block with PPE and the PMMA block with PSAN changes the glass transitions of the main components. In all studied blends, the PS block penetrates into the PPE

In-situ compatibilization of pet/ps blends through reactive copolymers

Abstract: Polymer blends of poly(ethylene terephthalate) (PET) and polystyrene (PS) are immiscible and incompatible, which has been well recognized. Styrene–glycidyl methacrylate (SG) copolymer has been synthesized by suspension polymerization and employed in this study as an in situ compatibilizer for the polyblends of PET and PS. This copolymer contains reactive epoxy functional groups that are able to react with PET end groups OH and COOH) under melt conditions to from SG-graft-PET copolymer. The presence of a small amount of phosphonium catalyst (200 ppm) accelerated the graft reaction and results in a better compatibilized blend. The compatibilized PET/PS blend has a smaller phase domain and higher viscosity than does the corresponding noncompatibilized blend. Mechanical properties of the compatibilized blends have also been improved significantly over the corresponding noncompatibilized blends. © 1993 John Wiley & Sons, Inc.

Polymer blends and alloys

Abstract: The state of thermodynamic miscibility of a polymer blend and its resulting phase behavior and mechanical properties is largely determined by the balance between enthalpic and entropic contributions to the free energy of mixing. Recent applications of this thermodynamic consideration are reviewed for a variety of binary and ternary blends of homopolymers and copolymers. Recent advances in predicting polymer blend miscibility and Lower Critical Solution Temperature behavior from liquid heats of mixing data, through use of a modified Guggenheim quasichemical model combined with the Sanchez lattice fluid model are discussed. Qualitative application of partial miscibility ideas to interfacial adhesion in multiphase polymer blends is also presented.

Method for making bicomponent fibers

Abstract: A method is disclosed for making thermoplastic bicomponent fibers by contacting under thermally bonding conditions (a) a first component being at least one high performance thermoplastic polymer, such as PET, PBT, nylon or the like, and (b) a second component which is olefinic and which forms at least a portion of the fiber's surface characterized by (b) including at least one grafted olefinic polymer, preferably at least one grafted linear ethylene polymer, having pendant succinic acid or succinic anhydride groups; whereby the fiber is dyeable. The bicomponent fibers made by this process can be in a variety of shapes (e.g., round, oval, trilobal, flat, or hollow) and configurations (e.g., symmetrical sheath/core or side-by-side or asymmetrical crescent/moon). The succinic acid or succinic anhydride groups are provided by grafting, respectively, maleic acid or maleic anhydride onto the linear ethylene polymers especially by a process wherein the grafting is done in a twin-screw, co-rotating extruder with the maleic acid or maleic anhydride being injected into a pressured zone of the extruder. The acid containing grafted linear ethylene polymer or polymer blends are dyeable in contradistinction to ungrafted linear ethylene polymers.

Electroviscoelastic effect of polymer blends consisting of silicone elastomer and semiconducting polymer particles

Abstract: Dynamic viscoelasticity of immiscible polymer blends consisting of silicone elastomer and semiconducting CuCl 2 - or FeCl 3 -doped poly(p-phenylene) particles was studied under the influence of electric fields. The dc electric fields enhanced storage and loss shear moduli of the polymer blends (electroviscoelastic effect). The ac electric fields with frequencies of less than 1 kHz also induced the electroviscoelastic effect. The electroviscoelastic effect was observed in the rubbery state of the blends with many lines of adjacent particles spanning the space between electrodes

An experimental-study of a model colloid-polymer mixture

Abstract: An experimental study of the phase behaviour of a model hard sphere colloid + non-adsorbing polymer mixture-sterically stabilised PMMA (radius= 217 nm) and polystyrene (r H = 12.8 nm) in cis-decalin is reported. It is found that the main effect of adding polymer was to expand the fluid-crystal coexistence region of the colloidal suspension, which spans 0.494 0.58) was shown to induce crystallization.

Sustained release matrix system using hydroxyethyl cellulose and hydroxypropyl cellulose polymer blends

Abstract: The present invention is directed to a novel sustained release matrix and oral dosage form comprising a homogeneous matrix formed from a wet granulation containing an effective amount of a medicament and a polymer blend of hydroxypropyl cellulose and hydroxyethyl cellulose. The present invention also discloses a novel process for making a sustained release oral dosage form comprising wet granulating a medicament with a polymer blend of hydroxypropyl cellulose and hydroxyethyl cellulose to form a homogeneous matrix, wherein the polymer blend is provided in an amount effective to control the release of said medicament, then forming the homogenous matrix into a solid oral dosage form.

Thermoplastic hotmelt adhesive

Abstract: 2141849 9403548 PCTABScor01 A thermoplastic hot-melt-type adhesive based on a polymer blend of polyolefins is disclosed. An oligomer of an .alpha.-olefin with at least 4 C atoms in the monomer and a molecular weight of the oligomer of up to 5,000, as well as other known additives, are added to the known mixture of a largely amorphous poly-.alpha.-olefin and of a largely crystalline poly-.alpha.-olefin. The impact strength, the viscosity and the flexibility at low temperatures are above all improved in this manner. These hot-melt-type adhesives are therefore suitable above all for glueing non-polar plastics in the automobile and electric industry.

Percolation behavior in morphology and modulus of polymer blends

Abstract: The tensile property of a plastic/rubber blend depends critically on the morphology and connectivity of the two phases. At low plastic volume fractions, the plastic phase forms isolated domains in the matrix of rubber phase, and the tensile property of the blend is largely controlled by the continuous rubber phase. As the plastic volume fraction increases, the plastic phase gradually connects into a pervasive network that eventually dominates the tensile and shear properties of the blend. The transition of the blend from a rubber-dominated to a plasticdominated behavior is a manifestation of percolation transition. The plastic volume concentration at which the transition takes place is the percolation threshold. Its dependence on morphology is discussed by contrasting the behaviors of anisotropic injection-molded specimens vs. isotropic compression-molded specimens of the two-phase blends of an amorphous thermoplastic polyester, PETG, and an ethylene-propylene-diene rubber, EPDM. It is found that the tensile modulus just above the percolation threshold obeys a power law as a function of the plastic volume concentration in excess of the percolation threshold. By analyzing the longitudinal tensile modulus of injection-molded PETG/EPDM specimens just above the threshold, it is shown that the scalar elastic percolation theory of de Gennes is at work here. For compression-molded PETG/EPDM specimens, it is found that the isotropic tensile modulus over the entire composition range obeys the symmetric effective medium theory.

Morphology and permeability in extruded polypropylene/ethylene vinyl‐alcohol copolymer blends

Abstract: Studies of the morphology of extruded polymer blend systems have shown that it is feasible to produce a laminar structure of an ethylene vinyl-alcohol copolymer (EVOH) dispersed phase in a polypropylene (PP) matrix phase. The laminar structure forms in the core of the extrudate when a slit die is incorporated into the extrusion process. Morphological studies, including a study of morphology development inside the die and studies of the effect of processing conditions on the morphology of the final product, revealed that the laminar structure is a result of die design. Processing conditions influence mainly the shape and dimensions of the laminar core region of the extrudate. Oxygen permeation tests have shown that the blend exhibits lower oxygen permeability than pure PP, when EVOH is incorporated as a dispersed phase into the system. Oxygen transmission rates obtained with a blend system approach those obtained with a multilayer coextrusion product, although only at high EVOH concentrations. Comparison of experimental data with theoretical permeation predictions shows that, up to 20 wt% EVOH, the reduction in oxygen transmission rate follows the prediction for a homogeneous system. At 25 wt%, a considerable decrease in oxygen transmission rate is noticeable, and the trend for higher EVOH contents is towards the behavior of a multilayer system.

Studies on compatibilization of blends of polypropylene and a thermotropic liquid crystalline polymer

Abstract: Thermotropic liquid crystalline polymers, LCPs, are frequently blended with thermoplastics to achieve an in situ composite structure. Significant mechanical reinforcement is obtained for the matrix polymer in the direction of the LCP fibers, but the transversal properties are often inferior because of the incompatibility of the components. Blends of LCP with polypropylene, and with three related matrix polymers, and PP/LCP blends with added potential compatibilizers were prepared and studied for their mechanical properties and morphology. A notable improvement in impact strength was achieved when a small amount of ethylene-based terpolymer was added as compatibilizer. © 1993 John Wiley & Sons, Inc.

Degradable polymer blends. I. Screening of miscible polymers

Abstract: Blends of biodegradable polymers having properties distinct from the individual polymer components, and that are suitable for use as carriers of pharmaceutically active agents, were prepared from two or more polyanhydrides, polyesters, and mixtures of polyanhydrides and low molecular weight polyesters. The blends have different properties than the original polymers, providing a mean for altering the characteristics of the polymeric matrix without altering the chemical structure of the component polymers. Aliphatic, aromatic, and copolymers of polyanhydrides were miscible in each other and formed less crystalline compositions with a single melting point which was lower than the melting point of the starting polymers. The polyesters: poly(lactide-glycolide), poly(caprolactone), and poly(hydroxybutyric acid) presented some miscibility in each other. However, the polyanhydrides were immiscible with the polyesters resulting in a complete phase separation both in solution or in melt mixing. Only low molecular weight polyesters (in the range of 2000) of lactide and glycolide, mandelic acid, propylenefumarate, and caprolactone presented some miscibility with polyanhydrides. Similarly, poly(orthoester) and hydroxybutyric acid polymers formed a uniform mixture with the anhydride polymers which had the two melting points of the original polymers. Drug release from polymer blends composed of poly(hydroxybutyric acid) or low molecular weight poly(lactic acid) with poly(sebacic anhydride) (PSA) showed a constant release of drug for periods from 2 weeks to several months as a function of the PSA content in the blend. Increasing the content of PSA, a fast degrading polymer, increases the release rate from the blend. © 1993 John Wiley & Sons, Inc.

Polymer mixture comprising an aromatic polycarbonate, a styrene-containing copolymer and/or graft polymer, and a polysiloxane-polycarbonate block copolymer, and 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 given type of polysiloxane-polycarbonate block copolymer. It has been found that the use of this given type of polysiloxane-polycarbonate block copolymer leads to a polymer mixture having improved impact strength properties. The polysiloxane-polycarbonate block copolymer used is built up from (a) 1-50% by weight of polysiloxane blocks of formula II and (b) 50-99% by weight of polycarbonate blocks of formula III, wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 each independently of each other represent a hydrogen atom, a hydrocarbyl or a halogenated hydrocarbyl, D is an integer from 5-140, Y is a hydrogen atom or an alkoxy, and wherein A is a bivalent hydrocarbon group having 1-15 carbon atoms, which bivalent hydrocarbon group may be substituted, is an --S--; an --S--S--; an --S--(O)--; an --S(O) 2 --; an --O--, or a --C-- and each X independently of each other is a hydrogen atom, a halogen or a monovalent hydrocarbon (see Figures).

Polymer blends of cycloolefin polymers and polyolefins

Abstract: A polymer alloy contains at least one cycloolefin polymer and/or at least one polyolefin and a block copolymer as phase promoter, which has different contents of monomers (norbornene derivatives and cycloolefins and/or acyclic olefins) in the individual blocks. To prepare the alloy, the individual polymers are combined and processed at elevated temperature under the action of shear forces.

Polymer rheology : theory and practice

Abstract: Some theoretical and numerical approaches to describing the viscoelastic properties of polymer systems. Rheological properties, relaxation behaviour, and rupture of polymers at temperatures above their glass transition temperature. Rheological relaxation properties of polymer blends. Rheological and relaxation properties of copolymers. Rheological and relaxation properties of filled polymers. Appendices. Index.