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  • 1
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 9 (1988), S. 229-236 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: High-impact polystyrene (HIPS) constitutes a mechanically attractive composite, consisting of a glassy matrix and a rubberlike particle phase (gel phase). Dynamic mechanical spectroscopy was performed for the polystyrene matrix for three different types of HIPS as well as for the concentrated gel-phase material, at the vicinity of the respective glass-transition temperatures (Tg). An approximate estimation of the gel-phase modulus was attempted by using known mechanical models. A comparison with experiments was also made. The modulus of the composite was found to be lower than the theoretical lower bound for particulate composites. This was attributed to a separate phase between gel particles and the matrix. A diffusion-type variation of the modulus of this mesophase layer was estimated, and a correlation between calculated fitting parametric exponents and impact behavior of HIPS was found. Moreover, the Tgs of the materials under investigation were also measured with two independent methods. It was found that all types of HIPS presented higher Tgs than the pure matrix by 5 to 10°C with the highest Tg found being that of the gel-enriched material. The shift of Tgs to higher temperatures was attributed to an eventual increase of the effective cross-link density of the matrix because of grafting.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 7 (1986), S. 1-8 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The dynamic mechanical properties of composite materials, consisting of an epoxy matrix filled with iron particles, were determined over a temperature range. The storage- and loss moduli were evaluated in a Dynastat apparatus, with the parameters being the volume fraction of filler and the test frequency. A theoretical model was developed for comparing the experimental results with the theoretical predictions. A satisfactory correlation was obtained for the glassy region of the composite.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 689-701 
    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: Thermal expansion coefficients and glass transition temperatures for metal-epoxy composites were determined experimentally. Results were in fair agreement with existing theories when certain fundamental assumptions were fulfilled. The effects of filler content and particle size as well as of adhesion between matrix and filler particles were investigated. The latter, in particular, was found to be of cardinal importance for the properties examined in the present work.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 3019-3025 
    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 thermomechanical behavior of particle composites was investigated in their transition region. In particular, the value of the glass-transition temperature Tg, which constitutes an upper limit for the structurally important glassy region, was examined. According to experimental evidence existing in the literature the introduction of a reinforcing filler in a polymeric matrix causes Tg of the latter to increase, unless mechanical imperfections counterbalance the reinforcing effect or even produce a Tg for the composite which is lower than that of the matrix. Based on mechanical theories, valid for the mechanical moduli of viscoelastic particle composites, a model was introduced that explains why the glass transition of composite materials may be reduced in some cases, whereas it may be increased in others. The concept of interphase between inclusions and matrix was used for the development of the model. Interphase is assumed to be a region, which is created between the matrix material and the filler particles, both considered as homogeneous and isotropic, whose thermomechanical properties and volume fraction may be determined from the overall thermomechanical behavior of the composite.
    Additional Material: 2 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 28 (1983), S. 3641-3649 
    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: Retardation spectra, derived from dynamic measurements of extension compliances along three decades on the logarithmic scale of frequencies in standard specimens prepared from a fiber-reinforced composite with their fibers parallel to the longitudinal axis of the specimens, have revealed the structure of the matrix material of the composite. The experimental results were used to prove that the physicochemical rearrangements in the vicinity of the inclusions, consisting of restrained development of the macromolecules and especially their side chains due to the presence of the other phase, concentration of voids and dirt, shrinkage stresses developed during curing and creating microcracks (radial as well as along the interface), are activated by the existence of high stress gradients and eventually stress singularities due to the strong adhesion developed between phases.
    Additional Material: 5 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. 3145-3153 
    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 influence of moisture absorption on the extent of the boundary interphase in particulate composites is thoroughly studied. It was found that, during the process of moisture absorption there is a variation of the extent of the boundary interphase, closely related to the degradation of the mechanical behavior of the composite, as well as to the percentage amount of moisture absorbed. An explanation of the observed relationship was advanced, based on a theoretical mechanism of absorption. This study complements a previous one, where the observed degradation of the thermomechanical properties of particulate composites due to moisture absorption was shown to be intimately interrelated with the state and extent of the interphase between fillers and matrix.
    Additional Material: 6 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 32 (1986), S. 6267-6279 
    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 extent of mesophase, which constitutes the boundary layer between the filler and the matrix of a composite, was defined in this paper along the whole viscoelastic spectrum of the polymeric substance constituting the matrix. The already established two-term unfolding model1-3 was based on thermodynamic measurements of the heat capacity jumps at the glass transition regions of the filled and unfilled substances in order to define the extent of mesophase. In this paper we dispense ourselves with these delicate measurements, based on Lipatov's theory, and we use values taken from the storage and loss compliances of the composite and its constituents, along the whole viscoelastic spectrum of the composite. It was shown that the extent of the mesophase, necessary to sustain the shearing loading between phases, appearing at the glass transition zone, where the loss-compliances presented their characteristic peaks of resonance, remained constant and almost independent of the respective values of mechanical properties at this critical region. It was shown that any set of values of the mechanical characteristic quantities, defining the composite and its constituents along the whole viscoelastic spectrum, is sufficient to evaluate the extent of the mesophase, and this boundary layer undergoes only negligible variations. Experimental evidence with typical E-glass polystyrene and other particulates, at various volume fractions of the filler, yielded a satisfactory coincidence with the results derived by using Lipatov's theory and a constancy of the mesophase thickness along the whole temperature range.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 3059-3063 
    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: Four polystyrene-polyurethane mechanical blends were prepared with 5, 10, 20, and 40% thermoplastic polyurethane, respectively. Their impact properties were compared with pure polystyrene and commerical types of impact polystyrene. The rheological properties of the blends were studied with DSC and dynamic mechanical spectroscopy. It was found that addition of softer polyurethane conglomerates embedded inside the polystyrene matrix, although increasing the toughness of the blend as expected from addition of the softer particulate, also increased the glassy region of the blends by shifting their Tgs to higher temperatures. A theory based on the interaction of phases was propounded explaining this phenomenon.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 903-910 
    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: A class of amine-cured epoxy resins containing various amounts of polysulfide plasticizer were subjected to dynamic testing during curing at high temperature. Both E modulus and loss factor were determined simultaneously. It was proved that the method allowed for rapid determination of the general pattern of the crosslinking procedure and the necessary curing time and, in general, that dynamic methods are most suitable for the mechanical characterization of polymers under curing at each stage of the curing cycle.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 1725-1734 
    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: A series of cold-setting epoxy polymers, plasticized with different amounts of plasticizer, ranging between 0 and 90% by weight of the amount of the epoxy prepolymer, were studied for their mechanical, optical, and fracture behavior properties. Quantities defining the mechanical properties were considered: the elastic modulus E, Poisson's ratio v, and fracture tensile stress σf. These were accurately measured with electric strain gauges in specimens tested in a 5-ton Instron tester. The optical behavior was characterized by the stress optical coefficients of the materials in both principal directions, α and β, as well as by the coefficient of optical anisotropy, ζ. The values of these quantities were measured by a Fizeau interferometric method. Finally, the optical method of caustics was applied to cracked epoxy polymer specimens to provide a new experimental technique for determining the stress optical properties of these polymers in terms of their mechanical properties. This method was used to check the previous results found by established experimental methods.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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