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  • 1
    Electronic Resource
    Electronic Resource
    Theoretical analysis of model compounds of substituted poly(acetylenes): conformation versus electronic properties (1987)
    Springer
    Polymer bulletin 18 (1987), S. 159-166 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The influence of the conformation of conjugated molecules on their electronic properties has been investigated using the extended Hückel theory. Dimers of acetylene and methylacetylene have been taken as model compounds of poly(acetylene) and poly(methylacetylene). Upon increasing the torsional angle between the two repeat units, both the band gap and the ionization potential increase, but the change is more pronounced with the former variable. This increase is not regular and becomes more important at angles larger than 30°. Non-planar conformations are then expected with poly(methylacetylene) and other n-alkyl monosubstituted poly(acetylenes) and explain their large band gap (i.e. blue shifting) in comparison with that of poly(acetylene). In addition, similar ionization potentials are expected for n-alkyl substituted poly(acetylenes) and, therefore, their different reactivity in presence of oxidizing agents has to be explained by the size of their substituents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261895
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  • 2
    Electronic Resource
    Electronic Resource
    A nonradiative energy transfer fluorescence spectroscopy study of poly(vinyl chloride)/poly(methyl methacrylate) blends (1991)
    Springer
    Polymer bulletin 26 (1991), S. 101-108 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The miscibility of poly(vinyl chloride)/atactic poly(methyl methacrylate (PVC/a-PMMA) blends was investigated by nonradiative energy transfer fluorescence spectroscopy using naphthalene-labeled PVC (PVC-N) with anthracene-labeled PMMA (PMMA-A), or anthracene-labeled PVC (PVC-A) with carbazole-labeled PMMA (PMMA-C). The two sets of results indicate an increase in energy transfer efficiency, corresponding to an increase in blend miscibility, as the PVC concentration increases and, more importantly, demonstrate that the same information about blend miscibility can be obtained using different donor-acceptor chromophore pairs and by changing the polymer to which the donor or the acceptor is attached. The effect of the tacticity of PMMA on its miscibility with PVC was also investigated using PMMA-C and PVC-A labeled polymers. The results confirm that PVC/a-PMMA blends are more miscible than PVC/i-PMMA blends over a large range of compositions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299354
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  • 3
    Electronic Resource
    Electronic Resource
    Fourier transform infrared study of segmental orientation in polymer blends (1988)
    Springer
    Microchimica acta 94 (1988), S. 283-286 
    Details
    ISSN: 1436-5073
    Keywords: orientation ; FTIR ; polymer blends ; PVC ; PMPPL
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of the macromolecular plasticizer poly(α-methyl-α-n-propyl-β-propiolactone), PMPPL, on the orientation of poly(vinyl chloride), PVC, has been studied by FTIR spectroscopy. The addition of PMPPL to PVC does not change significantly the degree of orientation of PVC segments. In blends, PMPPL chains are more oriented when the matrix is richer in PVC but the PMPPL orientation function always remains smaller than that of PVC segments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01205890
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  • 4
    Electronic Resource
    Electronic Resource
    Interdiffusion and adhesion at the inteface of a polystyrene-poly(2,6-dimethyl-1,4-phenylene oxide) blend below the glass transition temperature (1999)
    Springer
    Mechanics of composite materials 35 (1999), S. 441-446 
    Details
    ISSN: 1573-8922
    Keywords: polystyrene ; poly(2,6-dimethyl 1,4-phenylene oxide) ; interface ; interdiffusion ; strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Experiments on adhesion between the film surfaces of a polystyrene (PS)-poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) blend were carried out below the glass transition temperature of the bulk (T g ), at T=T g −13 and T=T g −23°C. The contact time varied from 2 to 1440 min. The strength at the interface was then measured at room temperature. The strength at the blend-blend interface was calculated using an additive diffusion model which takes into account the strength at homopolymer-homopolymer interfaces (PS-PS, PS-PPO, and PPO-PPO), surface concentration of components, and its variation with depth. A fair agreement between the calculated and measured strength was found. The results of the study support the concept of decreasing glass transition temperature near the surface of polymer glasses as compared with T g of the bulk.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02329331
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  • 5
    Electronic Resource
    Electronic Resource
    Crystallization and morphology of isotactic poly(methyl methacrylates) (1989)
    Springer
    Polymer bulletin 21 (1989), S. 621-626 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Several isotactic poly (methyl methacrylates) (iPMMA), with isotactic triad contents ranging from 46 to 100%, have been investigated after crystallization in the melt at different temperatures by differential scanning calorimetry, polarizing microscopy and small-angle light scattering. It was found that the crystallization of iPMMA, even of samples with high isotactic content, is slow. It never gives high degrees of crystallinity, but nevertheless leads to a spherulitic structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264144
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of optical purity of substituted β-lactones (1993)
    Springer
    Polymer bulletin 30 (1993), S. 223-228 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An octakis (3-O-butyryl-2,6-di-O-pentyl)-γ-cyclodextrin capillary gas chromatographic column was used to determine the optical purity of seven different β-lactones, having substituents in α- or β-position, and DL-lactide. The resolving power varied from one lactone to another. The optical purity values determined by GC were in agreement with those obtained from NMR spectroscopy or optical rotation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296853
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  • 7
    Electronic Resource
    Electronic Resource
    Kinetics of isomerization and doping of poly(t-butyl-acetylene) (1986)
    Springer
    Polymer bulletin 16 (1986), S. 7-12 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The kinetics of doping with I2and isomerization of poly(t-butylacetylene) has been studied. A first-order reaction in polymer and iodine was observed during the doping process, as was found for unsubstituted polyacetylene. However, for the isomerization process, a reaction order of 0.5 in iodine and no simple order in poly(t-butylacetylene) were determined. These results can be explained using a free radical mechanism where the free radicals catalyze the isomerization. In contrast to unsubstituted polyacetylene, the isomerization and doping processes are not related; isomerization occurs first, within about 30 min, and it is followed by doping at much later times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046602
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  • 8
    Electronic Resource
    Electronic Resource
    The transition moment angle of the v CN vibration in SAN copolymers (1994)
    Springer
    Polymer bulletin 32 (1994), S. 223-227 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Fourier transform infrared dichroism was used to determine the angle α between the CN transition moment and the chain axis, at 2238 cm-1, of SAN copolymers containing from 9 to 38 % AN units. This angle was found to be 90°.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306392
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  • 9
    Electronic Resource
    Electronic Resource
    Morphology of fractured polymer surfaces self-bonded below the glass transition temperature (1998)
    Springer
    Mechanics of composite materials 34 (1998), S. 473-482 
    Details
    ISSN: 1573-8922
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Previosly noncontact surfaces of polystyrene (PS) and poly(2,6-dimethyl 1,4-phenylene oxide) (PPO) were self-bonded in a lap shear joint geometry below the glass transition temperature Tg The joints were then fractured in tension at room temperature and the contact area was analyzed by means of scanning electron microscopy. Zones of plastic deformation were revealed on the surfaces of PS and PPO which had been bonded at Tg−33 and Tg−70°C, respectively, thus indicating interdiffusion across the interface. This result points to the lower Tg of the surface layer as compared with that of the bulk sample, in agreement with our previous studies. The unusually high self-bonding ability of PPO (at very low temperatures related to the bulk Tg) is presumably due to the low depth of penetration required to establish entanglements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02254711
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