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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 3565-3572 
    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: This paper deals with the coupling of polystyrene to a closely packed and highly ordered cationic vinylbenzyl silane (CVBS) on mica. It is shown that a thermal treatment is required for maximum retention of polystyrene on treated mica. Moreover, a thermal treatment at 250°C is much more effective than one at 170°C. The effect of the number of silane monolayers on mica was investigated. In general, one monolayer of CVBS gave optimum retention of polystyrene. The addition of peroxides further improved this retention and at the same time allowed the use of lower treatment temperatures. Some data are presented which consider the importance of the silane solution concentration and silane functional groups.
    Additional Material: 6 Ill.
    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 39 (1990), S. 285-300 
    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: In this study an immiscible blend of polypropylene(PP) and polycarbonate (PC) was examined. Experiments were carried out in an internal mixer and the objective was to examine the influence of the time of mixing, the speed of rotation of the rotors as well as the effect of time under quiescent conditions on the size and size distribution of the minor phase. The morphology was studied by light and electron microscopy and the photographs were quantitatively analyzed by semiautomatic image analysis. The effect of the time of mixing was studied for up to 20 min at three viscosity ratios for PC dispersed in PP. The most significant particle size deformation and disintegration processes take place within the first 2 min of mixing. After 2 min very little reduction in the size of the minor phase is observed up to 20 min mixing time, although some phase size/time dependence was observed at an intermediate viscosity ratio. The influence of rotor speed was also studied and the results indicate that this blend is insensitive to changes in the speed of rotation of the rotor over a three- to fourfold range. The effect of time at 250°C under quiescent conditions was studied at 7% and 23% composition (volume fraction) for PP dispersed in PC and also for PC in PP. Coalescence coarsening was observed only for 23% PC in PP where the particle size was found to increase by 75% after approximately 90 min at temperature.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1051-1055 
    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: This work deals with the effects of material and processing parameters on the mechanical behavior and morphology of noncompatlbilized polypropylene-polycarbonate (PP-PC) blends. The blends containing between 0 and 40 vol. percent of polycarbonate were compounded using a twin screw extruder and converted by injection molding using molds with rectangular as well as dogbone shaped cavities. The blends exhibit a complex skin-core morphology which evolves with the composition. Despite the absence of interfacial adhesion, the low strain modulus increases with PC concentration and follows approximately the Takayanagi model for systems with perfect adhesion. A slight increase of stiffness and strength with increasing PP/PC viscosity ratio is also observed. Weldline strength of these blends is generally poor and decreases with the increasing PC concentration.
    Additional Material: 11 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: 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.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Advances in Polymer Technology 14 (1995), S. 169-195 
    ISSN: 0730-6679
    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
    Notes: It is a well-known fact that weldlines are unavoidable in most injection-molded products of even moderate complexity. While there are many situations where they are barely perceptible, weldlines represent a potential source of weakness in molded parts. In injection molding weldlines are generated when two separate melt streams join either in multigated molds or as a consequence of flow around obstacles. The development of many interesting materials has been hampered by poor weldline strength. Among such materials are plastics reinforced with fibers or platelets, liquid crystal polymers, and a number of multiphase polymer blends. Weldlines have ever been called the “Achilles' heel” of these multiphase materials. This article is a review of the literature published on weldlines in injected parts. It deals primarily with the aspects related to the mechanical behavior of weldline-containing parts. It begins with a brief description of the phenomena important for the part formation in the mold, including those leading to weldlines, in addition to the techniques used to characterize weldline-containing parts. The following three sections consider the structure and properties of weldlines in neat amorphous and semicrystalline polymers, filled and reinforced plastics, and finally in polymer blends and alloys. In the last section methods developed for increasing the weldline strength are discussed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 1235-1244 
    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: Carbon analysis was used as a method for measuring the quantity of a cationic vinyl benzyl silane (CVBS) adsorbed onto the surface of mica. The results obtained indicate that CVBS can be applied from aqueous solution over a wide pH range with best treatment in neutral and acidic media. The amount adsorbed depends on the concentration of the treating solution in the lower concentration range while in the higher range, the adsorption is less dependent on concentration. The relationship, silane adsorption vs. time of treatment, shows a steplike dependence. It is suggested that each step corresponds to a monolayer coverage. The data indicate that CVBS on mica is a highly ordered and closely packed multilayer phase with the silane molecules oriented normal to the surface. The multilayer adsorption of silane onto silane in this system may be compared in some respects to polymer crystal growth.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 57 (1995), S. 1319-1332 
    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: Most injection molded objects contain defects known as weldlines. This defect may introduce an element of weakness affecting the object's performance. Weldlines are particularly problematic in multiphase materials where the situation may be exaggerated by component mismatch on the two sides of the interface that results in additional weakening when the two components do not adhere well to each other. In addition, weldline behavior is influenced by orientation and morphological effects. This paper deals with relationships between the structure and the mechanical properties in injection molded high density polyethylene polyamide-6 blends. The weldline effect is investigated in detail. Two molds were used to generate weldlines: a double-gated tensile bar cavity in which the weldline results from the meeting of two melt fronts flowing into each other from opposite directions, and a film-gated rectangular plaque mold with a circular insert that divides the melt front in two. Following the recombination of the fronts, there is additional flow as the melt fills the mold cavity. Two preparations containing 75 vol % of polyamide-6 and 25 vol % of polyethylene with and without compatibilizer were studied. In the first case, a compatibilizer was incorporated into the polyethylene prior to compounding with the polyamide-6. In the directly molded tensile bar the minor phase is strongly oriented parallel to flow. Only in the core, which represents about 10% of the sample thickness, do the dispersed phase particles assume spherical shape. The morphology of the weldline is closely related to that of the skin: the elongated structures are oriented parallel to the weldline plane. The effect of the compatibilizer on the mechanical properties (without the weldline) of the directly molded tensile bars is minor: It is overshadowed by the flow-induced morphology. The weldline strength loss is about 40% in the noncompatibilized blend. The introduction of the compatibilizer has restored the material's ability to yield and the properties are close to those measured without the weldline. For the second type mold, the effect of the weldline is less pronounced and the effect of the distance from the insert is negligible. The anisotropy is quite pronounced in the noncompatibilized blend. In compatibilized blends, all tensile properties are unaffected by the presence of weldline, except for the 2-mm-thick plaque in the position close to the insert. The properties in the direction parallel to flow are similar to the type I mold and not affected by the increase of plaque thickness. Consequently one may question the utility of the directly molded tensile specimens in studying various aspects of the mechanical behavior of multiphase materials where the flow-generated structure is very different from that found in “real” injection molded parts. © 1995 John Wiley & Sons, Inc.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1481-1481 
    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
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1345-1346 
    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: No Absract.
    Type of Medium: Electronic Resource
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  • 10
    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: The morphology of compatibilized polyolef in/polyamide blends was found to be significantly dependent on the concentration of an ionomer compatibilizer (polyethylene-methacrylic acid-isobutyl acrylate terpolymer) in the blend. For a dispersed phase content of 10% by weight, a maximum reduction in phase size was observed when only 0.5% by weight of ionomer was added to the blend, A more significant reduction of the dispersed phase size was observed when the minor phase was nylon, due to interactions which exist between the ionomer and the polyamide. These interactions have been confirmed by Fourier transform infrared spectroscopy. At high concentrations of the ionomer, flocculation of the nylon dispersed phase was observed. In comparison to one-step mixing, blends prepared by two-step or batch mixing were characterized by a smaller dispersed phase when nylon was the matrix, and a larger particle size when nylon was the minor phase. The results observed are explained in terms of a speculative model of the interactions occurring across the nylon-polvolefin interface.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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