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  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 781-788 
    ISSN: 0887-624X
    Keywords: DGEBA epoxy ; polycarbonate (PC) ; PMMA ; reactions ; IPN ; ternary polymer blends ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Morphology and reaction mechanisms were probed on a model reactive ternary blend system of polycarbonate (PC), poly(methyl methacrylate) (PMMA), and diglycidylether of bisphenol-A (DGEBA) epoxy by using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Molecular interactions/reactions between the components in the blends after heating treatments are discussed. It was found that reactions took place among the components and that an interpenetrating network was built. The possible reaction mechanisms and the resulting structures after the heating treatments were probed. In the blends, PC and DGEBA reacted to form a network, while PMMA remained free. The semiinterpenetration, however, did not result in a network interlocked into a homogeneous state. The single Tg of the heated ternary DGEBA/PC/PMMA blends actually did not reflect a homogeneous interpenetrating network. Due to relatively small PMMA domains, the ternary blend network exhibited a single Tg. Upon etching the PMMA domains from the blend by acetone, a clearly interpenetrating network of reacted PC and epoxy was exposed and confirmed. The reactions leading to such a morphology are discussed with experimental evidence. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 97-103 
    ISSN: 0887-624X
    Keywords: phenoxy ; polycarbonate (PC) ; exchange reactions ; morphology ; polymer blends ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Effects of trans reactions on the morphology, glass transition, and phase behavior in a classical blend system of a poly(hydroxyl ether bisphenol-A) (phenoxy) with bisphenol-A polycarbonate (PC) were investigated by differential scanning calorimetry (DSC) and optical microscopy. Although two Tgs were observed in the as-prepared PC/phenoxy blends, an apparently single, but broadened, Tg was found in the blends after heating at high temperatures, typically 200-250°C for short times. The optical microscopy results indicated that same scales of heterogeneity did exist in post-heated PC/phenoxy blends as well as unheated blends. Explanations were provided. After heating-induced interchange reactions (—OH and carbonate), randomly linked polymer chains might form at the numerous interfaces of the mutually occluded/included micro-domains. The majority of the chains in the micro-domains are forced to relax in coordinated motion modes after heating, thus showing a single Tg. A mechanism of trans reactions in interfacial regions was briefly discussed in supplement to earlier reports in the literature. © 1997 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 2041-2049 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Differential scanning calorimetry (DSC) and X-ray diffraction analysis were performed to study the multiple melting behavior and crystal forms of neat syndiotactic polystyrene (s-PS) in comparison with its miscible blends with amorphous atactic polystyrene (a-PS) or poly(2,6-dimethyl-p-phenylene oxide) (PPO). For neat s-PS annealed at 242 to 250°C, three melting peaks of changing intensity were observed (labeled I, II, and III from low to high temperature), while if annealed at high temperatures (254°C or higher) only two melting peaks were left. The missing peak was determined to be Peak-III for s-PS annealed at high temperatures. For the s-PS/a-PS or s-PS/PPO blends, two melting peaks were observed, and the missing peak is Peak-II. The missing Peak-II in the blend systems is attributed to the β-modification. Apparently, the condition of s-PS being compatible with a-PS or PPO is unfavorable for generating the β-modification upon melt crystallization. This study also showed that Peak-I is associated with the β-modification. Peak-III may be associated with the less stable β′ form, which can be transformed to the β form upon annealing at high temperatures. For the s-PS/a-PS or s-PS/PPO blends upon annealing at higher temperatures, Peak-III quickly decreases, leaving only a single melting peak (Peak-I) for the blends. The phenomenon of the decrease of Peak-III crystals in the blend is similar to that for neat s-PS annealed at high temperatures.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 2235-2244 
    ISSN: 0887-6266
    Keywords: TGDDM epoxy ; polycarbonate ; blends ; cure kinetics ; miscibility ; thermosets ; thermoplastics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Differential scanning calorimetry (DSC) has been applied to characterize the glass transition behavior of the blends formed by bisphenol-A polycarbonate (PC) with a tetrafunctional epoxy (tetraglycidyl-4,4′-diaminodiphenyl methane, TGDDM) cured with 4,4′-diaminodiphenylsulphone (DDS). A rare miscibility in the complete composition range has been demonstrated in these blends. Additionally, the blend morphology was examined using scanning electron microscopy (SEM) and a homogeneous single-phase PC/epoxy network has been observed in the blends of all compositions. Moreover, polycarbonate incorporation has been found to exert a distinct effect on the cure behavior of the epoxy blends. The cure reaction rates for the epoxy-PC blends were significantly higher due to the presence of PC. In addition, the cure mechanism of the epoxy blends was no longer autocatalytic. An n-th order reaction mechanism with n = 1.2 to 1.5 has been observed for the blends of DDS-cured epoxy with PC of various compositions studied using DSC. The proposed n-th order kinetic model has been found to describe well the cure behavior of the epoxy/PC blends up to the vitrification point. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2591-2598 
    ISSN: 0887-6266
    Keywords: epoxy microspheres ; phase inversion ; DGEBA ; PMMA ; blends ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) studies have been performed to reveal a crosslinked epoxy nature of the spherical particles formed in cured epoxy/DDS/PMMA blends. An interesting phase inversion phenomenon was observed in cured DGEBA/DDS/PMMA blends, which occurred at a relatively low thermoplastic composition of 20 phr PMMA in blends. A unique method of preparing crosslinked epoxy spheres of controlled sizes based on cure-induced phase inversion is described in this report. Several factors have been found to affect the geometry of the formed epoxy spheres. The volume fraction of PMMA in the blends strongly dominates the influence. With the increase of PMMA volume fraction in the blends, the spheres not only become smaller in sizes, but also more regular in the spherical geometry due to less impingement. The crosslinking density (DDS phr in the blends) has been found to influence the average sizes of the spheres. The cure temperature has relatively limited effects only when the PMMA loadings in the blends are relatively small. Various potential applications for the epoxy microspheres may be investigated in future studies. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2725-2735 
    ISSN: 0887-6266
    Keywords: blending ; polymorphism ; syndiotactic polystyrene (s-PS) ; amorphous polystyrene (a-PS) ; PPO ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: X-ray diffraction and optical microscopy characterization were performed to evaluate the phenomenon of alteration of polymorphism of syndiotactic polystyrene (s-PS) in the presence of other blending miscible polymers: poly(2,6-dimethyl-p-phenylene oxide) (PPO) or atactic polystyrene (a-PS). Both α and β crystal forms were observed in the neat s-PS sample, but only β-form crystal was found in miscible blends of s-PS with a-PS or PPO. The order and neighboring chain segments of neat s-PS are different from those of s-PS/PPO or s-PS/a-PS blends; thus, it is plausible that the greater randomness in the melt state of s-PS/a-PS or s-PS/PPO blends might be unfavorable for formation of α-form crystals from melts. The final spherulitic morphology the s-PS/a-PS or s-PS/PPO blends suggests that the amorphous-state miscibility of does not change much the spherulitic structure of s-PS. The radial growth rate is, in general, depressed with the presence of blending miscible polymers in s-PS of equal Tg or PPO of higher Tg. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2725-2735, 1998
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1985-1993 
    ISSN: 0887-6266
    Keywords: poly(phenylene sulfide) ; crystallization kinetics ; multiple melting ; solvent effect ; differential scanning calorimetry ; primary and secondary crystallization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Isothermal melt crystallization kinetics were investigated by differential scanning calorimetry (DSC) for virgin and α-chloronaphthalene solvent-treated poly(phenylene sulfide) (PPS) systems. The overall crystallization rates were found to be much faster for the solvent-treated PPS than for the virgin neat PPS. Additionally, the Avrami crystallization plot for the solvent-treated PPS samples appeared as two straight portions with an apparent discontinuity, but as a continuous straight line for the virgin PPS system. After the treatment of solvent dissolution and subsequent drying, the residual trace α-chloronaphthalene, upon being quenched to the crystallization temperatures, initiated some localized solvent-induced nuclei-like crystals in PPS. It was the nuclei that enhanced secondary crystallization in treated PPS during the second stage, and the higher extents of secondary crystallization in the solvent-treated PPS caused the apparent discontinuous break in the Avrami plots. The causes for the difference were explained and the mechanism of the sequential primary/secondary crystallization kinetics for the solvent-treated PPS was satisfactorily described with a proposed series-parallel crystallization model. ©1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 789-793 
    ISSN: 0887-6266
    Keywords: exchange reactions ; miscibility ; epoxy blend ; DGEBA ; PC ; PMMA ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: No abstract.
    Additional Material: 7 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 40 (1990), S. 1237-1256 
    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 kinetics of bisphenol-A diglycidyl ether epoxy (DGEBA) cured with trimellitic anhydride (TMA) were studied using differential scanning calorimetry (DSC) and FT-IR under isothermal temperatures in the range of 100-200°C. The effects of an onium salt catalyst and styrene monomer (a reactive diluent additive) on cure kinetics of the DGEBA/TMA resin systems were also investigated. For the uncatalyzed DGEBA/TMA system, the reaction was found to be second order up to a fractional conversion of 0.8, where a diffusion-limited reaction regime was observed as the matrix gelled. The apparent activation energy was calculated to be 11.3 kcal/mol. The cure reaction of the catalyzed DGEBA/TMA system was found to be second order up to a fractional conversion of 0.3 and first order thereafter. The apparent activation energy of the catalyzed resin system was calculated to be 12.3 kcal/mol. In the FT-IR investigation, it was discovered that the KBr powder catalyzed the cure reaction. Additionally, the styrene component in the styrene-DGEBA/TMA resin system polymerized independently in the later stage of the cure reaction of the epoxy component. Therefore, the styrene monomer had little effect on the kinetics of cure reaction of the epoxy system.
    Additional Material: 16 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 50 (1993), S. 1683-1692 
    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: Viscoelastic deformation of an interlaminar-toughened laminated composite was investigated, and effects of the interlaminar heterogeneity were examined. Dynamic mechanical experiments were performed on the laminates and neat matrix resins of the laminated composite in the temperature range of 82-210°C to probe linear time-temperature behavior. The reason for using torsional shear deformation for probing was that it usually is more dominated by the matrix. In the relatively low-temperature regime, time-temperature superposition was applicable, and the effect of the interlaminar heterogeneity was found to be not pronounced. A methodology based on the Arrhenius activation energy approach was proposed for predictions of long-term viscoelasticity of the heterogeneous-phase composite. The effects of the interlaminar toughening phase became more significant at temperatures greater than the Tg of the toughening phase and presented some limitations for accurate predictions of time-dependent behavior. © 1993 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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