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  • 1
    Electronic Resource
    Electronic Resource
    In situ polymerization preparation of blends of poly(methyl methacrylate) and poly(styrene-co-acrylonitrile) (1997)
    Springer
    Journal of materials science 32 (1997), S. 3463-3468 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The in situ polymerization of methyl methacrylate (MMA) with poly(styrene-co-acrylonitrile) (SAN) was studied. The PMMA/SAN in situ polymerization blends obtained were examined by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), tensile tests and scanning electron microscopy (SEM). The blends with compositions of 95/5, 80/20, 70/30, and 60/40 in weight ratios were miscible and had a single phase structure. However, the 90/10 PMMA/SAN in situ polymerization blend obtained was inhomogeneous and had a two-phase structure; polymerization-induced phase separation occurred during the preparation process of the blend. Both tensile strength and elongation at break increase with increasing SAN content up to 30 wt%. The degradation temperature and thermal stability of PMMA increased remarkably on incorporation of SAN up to 30 wt%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018633003127
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular design of high-performance polyimide membranes for gas separations (1996)
    Springer
    Journal of polymer research 3 (1996), S. 11-19 
    Details
    ISSN: 1572-8935
    Keywords: Permeability ; Polyimide ; Gas separation ; Diffusion ; Chain mobility
    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 main objective of this study is to acquire a better understanding of the relationships between the chemical structure of polymers and their permeability to different gases. This information is required for the development of new membrane processes for the separation of industrial gases. Based on our previous investigation of structure/permeability relationships, this study provides additional information on gas diffusivity and solubility data in different polyimides. The control factors of this relationship are identified as the structures of diamine and dianhydride, the degree of curing, and the chain morphology and mobilities. This study confirms that both the gas selectivity and permeability of polyimides can be enhanced simultaneously. The desired membrane materials can be achieved by synthesizing polyimides with over 60% aromatic rings and containing bulky functional groups, such as(CF3)2, which impede chain rotation and act as “spacers” to increase intersegmental distances. In addition, the diamine moieties must be short and rigid to produce a high gas selectivity. Polyimide membranes, then, behave as polymeric “molecular sieves”. This is demonstrated by the fact that the systematic changes in the structure of the polyimides affect mainly the diffusivity rather than thesolubility of the penetrant gases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01493376
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Phase behaviour, mechanical properties and thermal stability of thermosetting polymer blends of unsaturated polyester resin and poly(ethylene oxide) (1999)
    Springer
    Journal of materials science 34 (1999), S. 123-128 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The results of dynamic mechanical analysis reveal that crosslinked polyester resin (PER)/poly(ethylene oxide) (PEO) blends show a composition dependent glass transition temperature, Tg, which suggests that the blends studied are homogeneous in the amorphous state. The initial dynamic storage modulus, E', decreases with increasing PEO content up to 30 wt% in the blends, whereas E for both the 60/40 and 40/60 PER/PEO blends is close to that for the 80/20 PER/PEO blend and much larger than that for the 70/30 PER/PEO blend. The addition of crystalline PEO has a remarkable effect on the mechanical properties of crosslinked PER. Tensile testing shows that the elongation at break first increases greatly and then decreases slightly, whereas the Young's modulus and the tensile strength first decrease and then increase slightly with increasing PEO content in the blends. The variation of tensile properties was considered to be due to both the plasticization effect and the crystallization effect of PEO in the blends. The impact strength remains almost unchanged with increasing PEO content in the blends studied. No dramatic decrease of thermal stability for PER/PEO blends was observed for the blends with PEO content up to 30 wt%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004486129169
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Poly(N-phenyl-2-hydroxytrimethylene amine): Its blends with poly(∊-caprolactone) and water-soluble polyethers (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 211-218 
    Details
    ISSN: 0887-624X
    Keywords: poly(N-phenyl-2-hydroxytrimethylene amine) ; poly(∊-caprolactone) ; poly-(ethylene oxide) ; poly(vinyl methyl ether) ; polymer miscibility ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new polymer with pendant hydroxyl groups, namely, poly(N-phenyl-2-hydroxytrime-thylene amine) (PHA), was synthesized by a direct condensation polymerization of aniline and epichlorohydrin in an alkaline medium. The new polymer is amorphous with a glass transition temperature (Tg) of 70°C. Blends of PHA with poly(∊-caprolactone) (PCL), as well as with two water-soluble polyethers, poly(ethylene oxide) (PEO) and poly(vinyl methyl ether) (PVME), were prepared by casting from a common solvent. It was found that all the three blends were miscible and showed a single, composition dependent glass transition temperature (Tg). FTIR studies revealed that PHA can form hydrogen bonds with PCL, PEO, and PVME, which are driving forces for the miscibility of the blends. © 1997 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Examination of miscibility at molecular level of poly(hydroxyether of bisphenol A)/poly(N-vinyl pyrrolidone) blends by cross-polarization/magic angle spinning 13C nuclear magnetic resonance spectroscopy (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2291-2300 
    Details
    ISSN: 0887-6266
    Keywords: poly(hydroxyether of bisphenol A) ; poly(N-vinylpyrrolidone) ; polymer miscibility ; polymer blend ; solid-state (NMR) ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The miscibility of poly(hydroxyether of bisphenol A) (phenoxy) and poly(N-vinyl pyrrolidone) (PVP) was investigated by differential scanning calorimetry (DSC) and high-resolution solid-state nuclear magnetic resonance (NMR) techniques. The DSC studies showed that the phenoxy/PVP blends have a single, composition-dependent glass transition temperature (Tg). The S-shaped Tg-composition curve of the phenoxy/PVP blends was reported, which is indicative of the strong intermolecular hydrogen-bonding interactions. To examine the miscibility of the system at molecular level, high-resolution solid-state 13C nuclear magnetic resonance (NMR) technique was employed. Upon adding phenoxy to system, the chemical shift of carbonyl carbon resonance of PVP was observed to shift downfield by 1.6 ppm in the 13C cross-polarization (CP)/magic angle spinning (MAS) together with the high-power dipolar decoupling (DD) spectra when the concentration of phenoxy is 90 wt %. The observation was responsible for the formation of intermolecular hydrogen bonding. The proton spin-lattice relaxation time T1(H) and the proton spin-lattice relaxation time in the rotating frame T1ρ(H) were measured as a function of the blend composition. The T1(H) result was in good agreement with the thermal analysis, i.e., the blends are completely homogeneous on the scale of 20 ∼ 30 nm. The six results of T1ρ(H) further indicated that the blends were homogeneous on the scale of 40 ∼ 50Å. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2291-2300, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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