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  • 1
    ISSN: 1435-1528
    Keywords: Ionic interaction ; ionomer ; linear viscoelasticity ; nonlinear viscoelasticity ; damping function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The effect of ionic interaction on linear and nonlinear viscoelastic properties was investigated using poly(ethylene-co-methacrylic acid) (E/MAA) and its ionomers which were partially neutralized by zinc or sodium. Dynamic shear viscosity and step-shear stress relaxation studies were performed. Stress relaxation moduli G(t, y) of the E/MAA and its sodium or zinc ionomers were factorized into linear relaxation moduli G°(t) and damping functions h(y). The relaxation modulus at the smallest strain in each ionomer agreed with the linear relaxation modulus calculated from storage modulus G′ and loss modulus G″. In the linear region, the ionic interaction shifted the relaxation time longer with keeping the same relaxation time distribution as E/MAA. In the nonlinear region, the ionic interaction had no influence on h(y) when the ion content was low. At higher ion content, however, the ion bonding enhanced the strain softening of h(y).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 975-983 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The shear viscosity, the shear compliance, and their shear rate dependence were determined by a Weissenberg rheogoniometer, and the effect of the grafted poly(methyl methacrylate) chains on the intensification of the interaction at the interface between the ionomer matrix and the filler was discussed. Results were as follows: (1) The relative viscosity of the ionomer filled with MMA-grafted perlite to the matrix ionomer and the yield stress increased with increase in the volume fraction of perlite, and these behaviors were more remarkable in the case of the perlite with larger quantity of grafted PMMA. (2) The effective thickness of the immobilized matrix layer on the filler surface in the Ziegel equation and the crowding factor in the Mooney equation showed larger values in the case of the filled systems of MMA-grafted perlite than in the case of the unmodified perlite. (3) At the same total volume fraction which was the sum of the quantities of the perlite and the grafted PMMA, the relative viscosity and the crowding factor showed respectively a maximum with the quantity of grafted PMMA. (4) The shear compliance of these filled systems decreased with perlite content. A little effect of the amount of grafted PMMA on the compliance was observed at the same volume fraction of perlite. According to these rheological properties, it could be concluded that the grafted PMMA chains were effective in increasing the interaction between the ionomer matrix and the perlite at their interface, particularly in the lower shear rate region.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Effects of block copolymerized structure on nonlinear stress properties under elongational and shear deformation were investigated. Samples used in this study were poly(styrene-block-butadiene-block-styrene) (SBS, weight rate of S/B = 40/60) and polystyrene (PS) as a reference. Tensile stress-strain and shear stress relaxation properties were measured at the molten state. SBS showed high elasticity after reaching the yield point under elongational deformation at room temperature. PS melt showed substantial tensile stress increase after the yield point as strain rates increased. However, SBS melt did not exhibit noticeable tensile stress rise at higher elongation, and this property was almost independent of strain rates. Stress relaxation experiments revealed that the damping function of SBS melt was more strain-softening than that of PS melt. The results suggested that the block copolymerized structure decreases melt elasticity under elongational and shear deformation. A transmission electron micrograph indicated that the lack of melt elasticity in SBS melt is caused by orientation of the lamellar structure toward the stretched direction during deformation. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Co-extrusion by means of only one single screw with a double channel was studied. The effects of the operating conditions, the material properties and the screw geometries on the inter-channel flow and the output rate were determined. The flow mechanism and the application to the composites with stratified structures were discussed. The inter-channel flow rate decreased with decrease in the back pressure, the stock temperature, the screw rotational speed and the viscosity difference between polymer melts in both channels. The decrease in the compression ratios of channels, the barrier flight in the compression zone and the sealing at the flight clearance with the polyamide-packing reduced the inter-channel flow significantly without a decrease in the output rate. With this method, co-extrudates with distinctly stratified cross-sections were prepared. The single screw with double-channel could be applied effectively to the co-extrusion of composites with stratified structures such as sheath-and-core structures, and it is particularly suitable to distribute the additives heterogeneously or to enclose the waste polymer.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 1427-1437 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The rheological properties of the molten blends between polystyrene (PS) and styrenemethacrylic acid copolymer (S-MAA) or its metallic salts were determined with a Weissenberg rheogoniometer, and the mixed structure and the processability were discussed. Results were as follows. (1) The viscosities of the salts increased and the compliances decreased with increasing density of ionic crosslinkings. (2) The viscosities of the molten blend between PS and S-MAA or its salt increased steeply even at lower shear rate and the Newtonian flow region was not observed. (3) This shear-sensitivity of viscosity in low shear rate region increased with increasing temperature. (4) The effect of temperature on the viscosity of these blends deviated from the simple Arrhenius plot. (5) Some network structures are suggested for the blends between PS and S-MAA salts but they may be broken eventually under high shear rate or at high temperature. Therefore, the mixed structures and the flow mechanisms of these molten blends seem to change with shear or temperature.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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