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  • 1
    Electronic Resource
    Electronic Resource
    Phenylquinoxaline-Aryl ester block copolymers (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 3467-3480 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenylquinoxaline-aryl ester block copolymers were synthesized using well-defined phenolic hydroxyl terminated oligomers via a monomers/oligomer approach. Phenylquinoxaline oligomers with molecular weights of 5600 and 12,900 g/mol were prepared from the condensation of 1,4-bis(phenylglyoxalyl)benzene and 3,3′-diaminobenzidine in the presence of 4-hydroxylbenzil. The oligomers were copolymerized with isophthaloyl chloride and bisphenol A in tetrachloroethane to afford the desired phenylquinoxaline-aryl ester block copolymers. Copolymers with polyester compositions ranging from 15-50 wt % were prepared by controlling the monomers/oligomer stoichiometry. The majority of the materials displayed single phase morphologies with Tgs intermediate to the Tgs for the poly (phenylquinoxaline) and polyester homopolymers. Plots of the reciprocal of the Tg of the copolymers versus composition agreed well with values predicted by the Fox equation. A multiphase morphology was obtained for the copolymer with the highest polyester block length (⋍ 13,000 g/mol), which displayed a Tg at 190 and 300°C indicative of a glassy-glassy system. Significant improvement in the elongations were observed for the copolymers relative to the poly(phenylquinoxaline) homopolymer. The improved elongations were obtained with minimal sacrifice to the modulus. These materials represent the first example of poly(phenylquinoxaline) block copolymers from well-defined phenylquinoxaline oligomers.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080281222
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  • 2
    Electronic Resource
    Electronic Resource
    Imide-aryl ether ketone block copolymers (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2085-2097 
    Details
    ISSN: 0887-624X
    Keywords: imide-aryl ether ketone block copolymers ; multiphase morphologies ; mechanical and thermal properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Imide-aryl ether ketone block copolymers were prepared and their morphology and thermal and mechanical properties investigated. Two aryl ether ketone blocks were incorporated; the first was an amorphous block derived from bisphenol-A and the second block was a semi-crystalline poly(aryl ether ether ketone) prepared from a soluble and amorphous ketimine precursor. Bis(amino) aryl ether ketone and aryl ether ketimine oligomers were prepared via a nucleophilic aromaic substitution reaction with molecular weights ranging from 6,000 to 12,000 g/mol. The oligomers were co-reacted with 4,4′-oxydianiline (ODA) and pyromellitic dianhydride (PMDA) diethyl ester diacyl chloride in N-methyl-2-pyrrolidone (NMP) in the presence of N-methylmorpholine. The copolymer compositions, determined by H-NMR, of the resulting amic ester based copolymers ranged from 8 to 50 wt % aryl ether ketone or ketimine content. Prior to imide formation, the ketimine moiety of the aryl ether ketimine block was hydrolyzed (p-toluene sulfonic acid) to the ketone form producing the aryl ether ether ketone block. Compositions of this block were maintained low to retain solubility. Solutions of the copolymers were cast and cured to effect imidization, producing clear films with high moduli (ca. 2200 MPa) and elongations (33-100%). The copolymers displayed good thermal stability with decomposition temperatures in excess of 450°C. Multiphase morphologies were observed irrespective of the co-block type, block length or composition. © 1992 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301002
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  • 3
    Electronic Resource
    Electronic Resource
    Radiation resistance and molecular structure of poly(arylene ether sulfone)s (1991)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 2 (1991), S. 15-20 
    Details
    ISSN: 1042-7147
    Keywords: Radiation resistance ; Degradation ; Polysulfone ; ESR spectra ; Protective effect ; Gaseous products ; 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
    Notes: The radiation resistance of a series of aromatic polysulfones comprising alternating units of diphenyl sulfone and various aromatic diols has been investigated by measuring volatile products, soluble fractions and electron spin resonance (ESR) spectra. The yields of radicals at 77 K observed by ESR and of SO2 at 423 K have indicated that biphenol gives enhanced resistance to Y radiation, and tetramethyl bisphenol-A decreased resistance, relative to bisphenol-A, bisphenol-S and hydroquinone. The protective effect of bisphenol was confirmed by lower scission and crosslinking yields determined from the soluble fractions after high doses.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1991.220020102
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