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  • 1
    Electronic Resource
    Electronic Resource
    Influence of migration of plasticizer during melt mixing on the transitions and properties of PC/CAB blends (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 1015-1031 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Static and dynamic mechanical properties, morphology, and thermal behavior of polycarbonate (PC)/plasticized cellulose acetobutyrate (CAB) blends were investigated to determine whether the plasticizer of the CAB modifies the miscibility of the blend and the mechanical properties of this essentially incompatible blend. In spite of the lack of transparency of the blends, both dynamic mechanical and thermal analysis results show the presence, at all blend compositions studied, of a single glass transition temperature which varies with the composition of the blend. Considering the ternary nature of the blends, we propose that plasticizer migration and the difficulty of discerning the presence of one or two peaks in a narrow temperature range may account for the observed behavior. Scanning electron microscopy confirms the immiscibility of the blends. The blends show large positive deviations of the tensile moduli from linearity and very low ductility. The reported tensile strength data are discussed in terms of several different equations for composites. This mechanical behavior is explained as a consequence of the migration of the plasticizer and of its subsequent antiplasticizing effect on the properties of the blend.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090280703
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  • 2
    Electronic Resource
    Electronic Resource
    Control of interchange reactions of polycarbonate/polyarylate blends and their influence on physical behavior (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 6191-6207 
    Details
    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: Blends of polycarbonate of bisphenol A (PC) and a polyarylate of bisphenol A (PAr) are susceptible to showing interchange reactions in the melt state. The control of these reactions was carried out by means of the observation of the torque required to turn the Brabender and of its increase against the time due to copolymer formation in the processing equipment. Based on this variation and on glass transition temperature (Tg) measurements, the possibility of an exchange reaction in two steps in this blend was suggested. Tg measurements in melt- and solvent-cast blends also showed that this mixture is immiscible at all compositions and that, by copolymer evolution, a single Tg intermediate between those of the individual constituents can be found in all compositions. The influence of immiscibility on the mechanical properties of the blends was shown by the appearance of a minimum in large-strain properties at about 25% PAr. The behavior of the transesterified blends was very different showing a clear improvement of the tensile properties compared with those of the corresponding blends.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320805
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  • 3
    Electronic Resource
    Electronic Resource
    Physical and mechanical behavior of tetraglycidyl diaminodiphenyl methane (TGDDM)/m-phenylene diamine (m-PDA) epoxy systems (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 147-166 
    Details
    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 behavior of a tetraglycidyl diaminodiphenyl methane with a tetrafunctional aromatic diamine has been studied in terms of the influence of curing agent content and temperature. In this work, critical times corresponding to gelation are used as a measure of activation energy. The dynamic mechanical behavior has been used to analyze the curing extent of these epoxy systems with different amine contents before and after thermal posttreatment. The β-relaxation peak temperature is found to increase with the curing agent content and also after thermal posttreatment. This has been related to the rise of crosslinking extent. Dependence of flexural mechanical properties on curing agent content and the postcure process has also been determined.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460115
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of oxidation treatment of carbon powders on the cure kinetics of amine cured tetrafunctional epoxy resins (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 35 (1994), S. 345-353 
    Details
    ISSN: 0959-8103
    Keywords: TGDDM ; mPDA ; carbon powder ; cure kinetics ; rheology ; 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 tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM) type tetrafunctional epoxy resin containing carbon powders was cured with the stoichiometric amount of a tetrafunctional curing agent, namely m-phenylenediamine (mPDA). Carbon powders were oxidised with air or nitric acid. The influence of carbon powders on curing of the resin was followed by dynamic mechanical analysis, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Gelation and vitrification times were determined as a function of the variations of dynamic properties. The evolution of viscoelastic modulus during curing of the different mixtures showed that untreated carbon powder clearly accelerated the kinetics of curing whilst oxidation of carbon powders could remove their catalysing effect. These results were confirmed by monitoring the changes in conversion of epoxy and amine groups during cure using the FTIR technique. DSC experiments also showed the influence of carbon powder as a catalyst and the loss of the catalysing effect as a consequence of chemical treatment.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1994.210350407
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  • 5
    Electronic Resource
    Electronic Resource
    Polycarbonate/phenoxy blends: Physical behavior and development of interchange reactions in melt-processing conditions (1986)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 1478-1482 
    Details
    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 miscibility of the polycarbonate of bisphenol A with the polyhydroxyether of bisphenol A was analyzed using differential scanning calorimetry and the, results are compared with the torque data obtained using a Brabender Plasticorder. The possibility of interchange reactions was analyzed by means of the observation of the melt-viscosity variation versus processing time in the mixer-bowl. These reactions form graft-copolymers that develop into crosslinked copolymers at higher residence times. It was also shown that the speed of these reactions depends on the processing temperature. The variation produced on the glass-transition temperature because of branching was also analyzed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760262103
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanical behavior of polycarbonate/phenoxy blends before and after interchange reactions (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1126-1131 
    Details
    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: Melt-mixed blends of polycarbonate/phenoxy were obtained before and after Interchange reactions by controlling the processing time. The dynamic mechanical analysis of the physical and reacted blends confirmed the immiscibility of the pair and the displacement of the glass-transition temperatures of the mixtures; this displacement was seen more clearly in the reacted mixtures, and at phenoxy-rich contents, even a single phase can appear. The exchange reactions resulted in a mechanical behavior that showed both a higher modulus and greater tensile strength in the reacted blends. The ductility was close to linearity for the physical blends and probably would be improved in the reacted mixture with a lower processing time.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281707
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  • 7
    Electronic Resource
    Electronic Resource
    Dependence of dynamic mechanical behavior of DGEBA/DDM stoichiometric epoxy systems on the conditions of curing process (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 75-87 
    Details
    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: Dynamic viscoelastic properties of diglycidyl ether of bisphenol A (DGEBA) cured with diaminodiphenylemethane (DDM) have been studied. The relaxation spectra of stoichiometric mixtures have been investigated as a function of the casting procedure and the thermal history during curing. Variations on the temperatures of the loss peaks and also on their magnitude have been observed when a solvent was employed to cast the mixtures. These variations have been attributed to the existence of high crosslinked regions formed at the earlier stage of curing inside the overall matrix. The results obtained from mixtures cured with different thermal histories underline the importance of adequate selection of curing conditions in order to obtain the optimum properties for these materials. Differences in crosslink density amongst the mixtures cured at different conditions have been correlated to the extent of reaction obtained by infrared measurements. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070550108
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of chemical structure of hardener on curing evolution and on the dynamic mechanical behavior of epoxy resins (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 56 (1995), S. 177-192 
    Details
    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 diglycidyl ether of bisphenol-A-type difunctional epoxy resin was cured with different amine-type curing agents at stoichiometric ratios. The crosslink process was followed by viscosimetry and differential scanning calorimetry. The gelation time and the apparent activation energy were found to be strongly dependent on the structure of the hardener. The heat of reaction did not vary significantly when the hardener was changed. An interpretation based on structural aspects such as amine reactivity, steric hindrance, and chain rigidity is proposed for the variations corresponding to the curing process. Master viscosity curves have been built up for all mixtures. The effect of the hardener on the glass transition temperatures of the different mixtures has been analyzed taking into account the crosslink density, measured by the rubber modulus obtained by dynamic mechanical studies, and the chemical structure of the hardener chains. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070560208
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