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  • 1
    Electronic Resource
    Electronic Resource
    Surface and bulk phase separation in block copolymers and their blends. Polysulfone/polysiloxane (1988)
    s.l. : American Chemical Society
    Macromolecules 21 (1988), S. 2689-2696 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00187a007
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  • 2
    Electronic Resource
    Electronic Resource
    Structure and Properties of Butadiene-tert-Butyl Methacrylate and Butadiene/Styrene-tert-Butyl Methacrylate Triblock Copolymer Ionomers (1995)
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 7822-7830 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00127a032
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  • 3
    Electronic Resource
    Electronic Resource
    Chemical composition distribution of a graft copolymer prepared from macromonomer: fractionation in demixing solvents (1989)
    s.l. : American Chemical Society
    Macromolecules 22 (1989), S. 861-865 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00192a058
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  • 4
    Electronic Resource
    Electronic Resource
    Chemical modification of matrix Resin networks with engineering thermoplastics (1985)
    Springer
    Polymer bulletin 13 (1985), S. 201-208 
    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 Functionally terminated bisphenol-A polysulfone oligomers were used in the modification of Epon Resin 828/4,4′-diamino-diphenylsulfone (DDS) network system. Phenolic hydroxyl terminated PSF oligomers were first capped with a large excess of bisphenol-A diglycidyl ether or Epon Resin 828 at both ends and then the resulting system was cured with DDS, in a two-step process. During these studies molecular weight and the amount of PSF oligomers incorporated into the network were varied and their effect on the overall properties of the resulting systems were investigated. The capping and curing reactions were followed by using FT-IR and NMR spectroscopy, GPC, HPLC and DSC techniques. As a function of the oligomer molecular weight, SEM studies showed the formation of two-phase structures with ductile PSF particles dispersed in the continuous epoxy matrix. Mechanical characterization and fracture toughness measurements showed a remarkable increase in KIC or gIC values of the modified networks over that of control, without significant loss in the modulus. This work would appear to be one of the first studies where well bonded ductile glassy modifiers have significantly improved the fracture toughness of highly crosslinked networks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254652
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  • 5
    Electronic Resource
    Electronic Resource
    Novel supercritical fluid techniques for polymer fractionation and purification (1984)
    Springer
    Polymer bulletin 12 (1984), S. 491-497 
    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 Supercritical fluids which combine the properties of both gases and liquids also show very unusual pressure dependent dissolving power. When such fluids are used as solvents in various separation processes, it is possible to achieve effective fracticnation or purification in a number of different systems which are difficult to obtain by conventional techniques. In this communication a brief summary of the basic aspects of supercritical fluids will be given. The application of this novel technique for the fractionation and purification of polymeric and oligomeric organofunctional siloxanes will be illustrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00958654
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  • 6
    Electronic Resource
    Electronic Resource
    Novel supercritical fluid techniques for polymer fractionation and purification (1984)
    Springer
    Polymer bulletin 12 (1984), S. 499-506 
    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 α, ω-carboxypropyl terminated polydimethylsiloxane oligomers (PSX) having molecular weights (Mn) of 2000 and 6400 g/mole respectively were fractionated by using supercritical carbon dioxide. Parent materials and the fractions were characterized by FT-IR spectroscopy, end group titrations and GPC. Polydispersity of each fraction was determined from the analysis of GPC curves. A calibration curve was also plotted by using Mn values from titration and peak elution volumes from GPC. Even without process optimization we were able to obtain fractions having (Mw/Mn) values between 1.1 and 1.3 compared to the parent materials (PSX-2000 and PSX-6400) which showed polydispersities of 1.6 and 2.1 respectively. The ability to prepare such narrow fractions should be of considerable interest both for academic studies as well as for polymeric biomaterials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00958655
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of poly(dimethylsiloxane) based liquid crystals (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 2909-2931 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A novel set of low molecular weight copolymers have been synthesized which were based on the attachment of mesogenic groups to the terminal points of oligomer backbones. The placement of the groups at the end of the chains apparently allowed a second phase to form more easily than if the groups were attached along the backbone as pendant groups. The nature of the coupler or spacer was determined to influence whether the end groups crystallized or formed liquid crystallinity. The observation of liquid crystallinity was found to depend primarily on the relative concentration of mesogen to backbone molecular weight. Depending upon the specific coupler, there existed two critical values of molecular weight between which mesophase behavior was observed. Below a certain value, the end groups were found to crystallize. Above another critical value, there was no measureable second phase. Liquid crystallinity was only observed when the molecular weight was intermediate between the two critical values.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021871217
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular weight characterization of soluble high performance polyimides. 1. Polymer-solvent-stationary phase interactions in size exclusion chromatography (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1429-1439 
    Details
    ISSN: 0887-6266
    Keywords: soluble aromatic polyimides ; size exclusion chromatography ; molecular weight characterization ; mobile phase/stationary phase interactions (SEC) ; high performance polyimides ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Soluble, fully cyclized m-amino phenyl acetylene terminated polyimides based on several anhydride/diamine monomers were prepared in N-methylpyrrolidine (NMP) and cyclized by solution imidization to controlled molecular weight. The polyimides and a polyamic acid precursor were successfully analyzed by size exclusion chromatography (SEC) utilizing online parallel coupled refractive index and differential viscometer detectors. The calculated Mnvalues were varied from 3,000 to 20,000 daltons. N-methylpyrrolidone (NMP), tetrahydrofuran (THF), and chloroform served as mobile phases for the cross-linked polystyrene gel packings. Normal retention behavior of the polyimides was observed in chloroform, THF, and NMP containing LiBr, or in NMP stirred over P2O5 before use. Values of Mark-Houwink-Sakurada exponents for narrow distribution linear polystyrene indicate that pure NMP and NMP with 0.06 M LiBr are good solvents for polystyrene standards at 60°C. In contrast, SEC behavior of polyimides in pure NMP leads to splitting of the peaks with the major portion observed to pass through the columns at the exclusion limit. In contrast to strong polymeric chain expansion of the polyamic acid in dilute solution, presumably due to a polyelectrolyte effect, no increase of intrinsic viscosity of polyimide samples in pure NMP was observed. This exclusion effect of polyimides analyzed in NMP is discussed in terms of possible ion-exclusion from pores of the stationary phase. Differences in polystyrene calibration in NMP with or without additives and the temperature dependence of calibration curves in these mobile phases is discussed as well. ©1995 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090331001
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  • 9
    Electronic Resource
    Electronic Resource
    Generation and structure-property behavior of novel liquid crystalline foams produced via a gas supersaturation technique (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 933-951 
    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: Linear and star-branched polyoxybenzoate-polyoxyphenoxybenzoate copolymers (POB-co-POPB) at a 65/35 molar ratio were synthesized via melt acidolysis using AB-type monomers and branching agents. By controlling the molecular weight and topology of these polymers, both melt processability and solid-state CO2 gas absorption behavior were enhanced. POB-POPB copolymers with a molar ratio 65/35 showed a glass transition of 143°C and completion of melting at ca. 300°C. POB-POBP copolymers with a systematically increasing branching agent content showed a systematically decreasing peak intensity in wide-angle X-ray diffraction, indicating that increasing branch-point concentration leads to a decrease in liquid-crystal ordering. Star-branched POB-POPB copolymers showed greatly enhanced carbon dioxide gas absorption behavior relative to their linear counterparts. Whereas CO2 blown foams of linear POB-co-POPB produced by the gas supersaturation technique had a relatively high density and showed highly anisotropic bubble growth, well-defined, nearly isotropic foams of star-branched POB-co-POPB with a mean cell size from 200 to 400 μ were made using the gas supersaturation technique. Structural features were characterized via scanning electron microscopy, and mechanical properties were determined by indentation testing with a 0.25 in. ball indenter. These LCP foams exhibit relative mechanical properties similar to polystyrene and microcellular polycarbonate foams. A strong inverse relationship was noted between cell size and modulus for liquid crystalline foams with a cell size below 400 μm. © 1994 John Wiley & Sons, Inc.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070530709
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  • 10
    Electronic Resource
    Electronic Resource
    Molecular weight characterization of soluble high performance polyimides. 2. Validity of universal SEC calibration and absolute molecular weight calculation (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1441-1448 
    Details
    ISSN: 0887-6266
    Keywords: soluble high-performance fully cyclized polyimides ; molecular weight characterization ; size exclusion chromatography (SEC) ; LALLS ; in-line viscosity detection ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Six different soluble high-performance aromatic polyimides, each prepared by solution imidization to three controlled average molecular weights, were analyzed by size exclusion chromatography (SEC) using on-line parallel coupled refractometric and viscometric detectors. N-methylpyrrolidone (NMP) with 0.06 M LiBr and NMP stirred over P2O5 were used as mobile phase for four of the polyimides; NMP with 0.06 M LiBr and NMP stirred over P2O5 were used as mobile phases for four of the polyimides; NMP with 0.06 M LiBr tetrahydrofuran (THF) and chloroform served as mobile phases for the other two polyimides. For all the samples the stationary phase in the SEC columns was cross-linked polystyrene beads. Molecular weight averages of the polyimides were calculated using universal SEC calibration with polystyrene standards in each solvent. The agreement of the calculated molecular weight averages in the different solvents confirms that the universal SEC calibrations are valid for these semiflexible polymers. There was good agreement with weightaverage molecular weights obtained by low-angle laser light scattering (LALLS) performed in pure NMP. Intrinsic viscosity and molecular weight data for a series of nine samples of one polyimide covering a Mw = 20,000-70,000 g mol-1 interval were treated to obtain Mark-Houwink-Sakurada constants. Unperturbed chain dimensions of this polyimide were obtained by application of the Stockmayer-Fixman extrapolation procedure to these data. ©1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090331002
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