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  • 1
    Digitale Medien
    Digitale Medien
    Geometrical constraints on microstructural development in block copolymer ultrathin films (1989)
    Springer
    Colloid & polymer science 267 (1989), S. 808-817 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Blockcopolymers ; ultrathinfilms ; polymericmicrostructures ; microphaseseparation ; microstructuraldimensions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The fact that microstructures form in microphase-separated block copolymers, endowing the materials with unique thermo-mechanical properties, is well-established. However, no thermodynamic theories directly address the problem of microstructural development in ultrathin films, which might be useful as adhesives or resists. To predict the microstructural dimensions in such films, a model based on unit-cell geometries and material/volume balances is developed. Predictions of the ratio of the characteristic length of the domain core to domain repeat distance are obtained for poly (styrene-butadiene) diblock (SB) copolymers at 298 K. The finite interphase region is included in the volume balances with the parameterf, the volume fraction of interphase material, obtained from a modified version of the Leary-Henderson-Williams thermodynamic theory and shown here not to be a strong function of composition. An approach, implementingf, for accurately estimating the critical molecular weight of microphase separation in the strong-segregation limit (M c ), as a function of bulk composition for monodisperse SB copolymers at 298 K, is also presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01410120
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  • 2
    Digitale Medien
    Digitale Medien
    Triblock copolymer/homopolymer blends: conformational changes, microstructural transition and macrophase separation (1998)
    Springer
    Journal of materials science 17 (1998), S. 545-549 
    Details
    ISSN: 1573-4811
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006565418979
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  • 3
    Digitale Medien
    Digitale Medien
    Enhanced Barrier Performance of SiOx-Modified Polymer Substrates: Some Morphological Considerations (1999)
    Springer
    Journal of materials science 18 (1999), S. 311-315 
    Details
    ISSN: 1573-4811
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006687324051
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  • 4
    Digitale Medien
    Digitale Medien
    Domain formation in thin films of a thermotropic copolymer (1990)
    Springer
    Journal of materials science 9 (1990), S. 935-936 
    Details
    ISSN: 1573-4811
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00722177
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  • 5
    Digitale Medien
    Digitale Medien
    Characteristics of thermotropic copolymer films cast from solution (1990)
    Springer
    Journal of materials science 9 (1990), S. 589-591 
    Details
    ISSN: 1573-4811
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00725886
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  • 6
    Digitale Medien
    Digitale Medien
    Degradation kinetics of glass-reinforced polyesters in chemical environments (1996)
    Springer
    Journal of materials science 31 (1996), S. 4757-4765 
    Details
    ISSN: 1573-4803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Numerous studies have been conducted to elucidate the mechanism(s) by which glass-reinforced polyesters (GRPs) degrade in aqueous solutions varying in salt concentration, pH and temperature. In this work, we examine the degradation kinetics of two GRPs in two organic solvents, 1,1,1-trichloroethane (TCE) and toluene, to ascertain if these laminates could be utilized in fuel or solvent storage and transportation applications. The tensile strength of isophthalic and vinyl ester laminates is not significantly affected (〉85% retention) by TCE after 270 days of immersion. While incorporation of a polyethylene terephthalate (PET) or C-glass surface veil does not improve tensile strength retention and, in fact, reduces the flexural strength of the vinyl ester GRPs, these veils preserve surface finish by reducing blistering. In toluene, the GRPs behave quite differently. A marked increase in toluene absorption into the vinyl ester laminate is accompanied by a substantial reduction in tensile strength retention (with or without a surface veil). From these results, a two-stage degradation mechanism for vinyl ester in toluene is proposed in which the first stage corresponds to diffusion-limited plasticization and the second reflects matrix relaxation/swelling.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00355858
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  • 7
    Digitale Medien
    Digitale Medien
    Replicated surface morphologies of lamellar and bicontinuous diblock copolymer blends (1996)
    Springer
    Journal of materials science 15 (1996), S. 1009-1011 
    Details
    ISSN: 1573-4811
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00274890
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  • 8
    Digitale Medien
    Digitale Medien
    Degradation kinetics of glass-reinforced polyesters in chemical environments (1996)
    Springer
    Journal of materials science 31 (1996), S. 4745-4756 
    Details
    ISSN: 1573-4803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Glass-reinforced polyesters (GRPs) are attractive in structural applications due to their strength-to-weight ratio and resistance to chemical attack. For marine and processing applications, in particular, GRPs must withstand long-term exposure to brine and either highly acidic or basic aqueous solutions. In this work, we report on the degradation of two GRP laminates, a pultruded isophthalic polyester (IPE) and a hand-moulded vinyl ester (VE), in brine (5% w/v NaCl) and a 10% w/v NaOH(aq) solution over the course of 270 days at 25°C. Tensile and flexural strengths have been measured as a function of immersion time and reveal that the IPE resin is more susceptible to water permeation and fibre-resin debonding than the VE. While the IPE laminate undergoes dramatic tensile strength deterioration in NaOH(aq) within the first 30 days of immersion, the VE resin is far more resistant to degradation in either solution. These measurements are consistent with surface features imaged with electron microscopy. Incorporation of polyethylene terephthalate (PET) or C-glass surface veils into these laminates is not generally beneficial for property retention, since the veils produce more interfaces and enhance water absorption through wicking.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00355857
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  • 9
    Digitale Medien
    Digitale Medien
    Microstructure of a thermotropic random copolymer of hydroxybenzoic acid, isophthalic acid and hydroquinone (HBA-IA-HQ) (1991)
    Springer
    Journal of materials science 26 (1991), S. 4234-4240 
    Details
    ISSN: 1573-4803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Transmission electron microscopy has been used to study microstructural features in a thermotropic copolyester composed of 4-hydroxybenzoic acid, isophthalic acid and hydroquinone residues. Selected-area electron diffraction patterns indicate that thin sheared samples of the pure copolymer, and of an analogue containing glass filler, exhibit a dual molecular orientation in which the meridional maxima are closely periodic in scattering angle. Dark-field (DF) imaging in one set of the diffuse equatorial reflections reveals “bands” which have an average period of 200 nm. Annealing the material in the solid state at 250 °C leads eventually to a change in the structure in which the banded texture is replaced by regions of uniform orientation within which the molecules are aligned with the shear axis. Needle-like diffracting crystalline entities, measuring approximately 80 nm long, in the direction of the molecular chain axis, and 5–8 nm thick, have been imaged in DF using the first meridional reflection as the source of diffraction contrast.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00553516
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  • 10
    Digitale Medien
    Digitale Medien
    Microstructure of a thermotropic random copolymer of hydroxybenzoic acid, isophthalic acid and hydroquinone (HBA-IA-HQ) (1991)
    Springer
    Journal of materials science 26 (1991), S. 4234-4240 
    Details
    ISSN: 1573-4803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Transmission electron microscopy has been used to study microstructural features in a thermotropic copolyester composed of 4-hydroxybenzoic acid, isophthalic acid and hydroquinone residues. Selected-area electron diffraction patterns indicate that thin sheared samples of the pure copolymer, and of an analogue containing glass filler, exhibit a dual molecular orientation in which the meridional maxima are closely periodic in scattering angle. Dark-field (DF) imaging in one set of the diffuse equatorial reflections reveals “bands” which have an average period of 200 nm. Annealing the material in the solid state at 250 °C leads eventually to a change in the structure in which the banded texture is replaced by regions of uniform orientation within which the molecules are aligned with the shear axis. Needle-like diffracting crystalline entities, measuring approximately 80 nm long, in the direction of the molecular chain axis, and 5–8 nm thick, have been imaged in DF using the first meridional reflection as the source of diffraction contrast.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02402974
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