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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 42 (1999), S. 675-682 
    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 Four three-armed poly(glycidyl ether)s with biphenyl mesogenic group and various lengths of spacer, new side-chain liquid crystalline polymers, were synthesized by cationic ring-opening polymerization of the corresponding monomers in the presence of 2,2-dihydroxymethylbutanol and BF3·OEt2 as initiator. The structures of the obtained poly(glycidyl ether)s were verified by 1H and 13C NMR spectroscopy, and their liquid crystalline behaviors were studied by differential. scanning calorimetry (DSC and optical polarizing microscopy (OPM).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 3403-3408 
    ISSN: 0887-624X
    Keywords: star-shaped ; poly(THF) ; ion-coupling ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The prepoly(tetrahydrofuran) [poly(THF)] capped with hydroxyl and tetrahydrothiophenium groups was prepared using tetrahydrothiophene to terminate the living cationic polymerization of THF initiated by BF3·OEt2 and epichlorohydrin (ECH) at low conversion. Well-defined star-shaped poly(THF) polyols were synthesized by an ion-coupling reaction of the prepoly(THF) with tri- or tetrafunctional benzenecarboxylates, respectively, and this process proceeded by precipitation when the solution of the prepolymer in THF was added to an aqueous solution containing an excess of the corresponding coupling reagent. GPC studies showed that all of the carboxylate groups of every coupling reagent molecule took part in the ion-coupling reaction simultanously. This was confirmed by IR spectra. Almost all of the prepolymers were coupled to form star polymers after repeating the precipitation four times. 1H-NMR illustrated that both the star-shaped polymers and the prepolymers contained primary and secondary hydroxyl end groups. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3403-3408, 1997
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2151-2155 
    ISSN: 0887-624X
    Keywords: epoxy resin ; prepolymer ; spiro orthocarbonate ; curing reaction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Prepolymers were prepared by the reaction of 3,9-dihydroxyethyl-3′9′-dibenzyl-1,5,7,11-tetraoxaspiro(5,5)undecane with 4,4′-diphenylmethane diisocyanate (MDI) and 1,6-hexa-methylene diisocyanate (HDI). The number-average molecular weights of the prepolymers can be controlled by changing the mole ratios of spiro compound and diisocyanates. Kinetic studies of the cure reaction for the epoxy resin system modified with or without prepolymers were followed by a HLX-1 dynamic torsional vibration apparatus. The results indicated that gel time (tg) and activation energy (Ea) increased as the content of prepolymers in the epoxy resin system increased. A difference with the cure reaction of the pure epoxy resin, the second-order reaction for the epoxy resin modified with the prepolymers, was obtained. Rate constants (k) of the cure reaction are 0.231 min-1 for the epoxy resin, and 0.312 min-1 for the modified epoxy resin. The mechanism of the cure reaction was discussed. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 195 (1994), S. 119-128 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new unsaturated bicyclic ether, 2-methylene-7-oxabicyclo[2.2.1]heptane (4) was synthesized by successive Diels-Alder addition of furan to acrylonitrile, hydrogenation of cyano compound 5, and Hofmann degradation of the quaternary ammonium hydrate 7 derived from the amine 6. Cationic polymerization of the monomer 4 was carried out in CH2Cl2 using BF3 · OEt2, PF5, SbCl5 and SnCl4 as catalysts in the temperature range of -20 to -25°C. White or slightly yellow powdery polymers of low molecular weight were obtained with PF5 and BF3 · OEt2 as catalysts, while no polymer was obtained with SbCl5 and SnCl4 as initiators. The IR, 1H and 13C NMR spectra of the polymers indicated that they consist of three kinds of repeating units, that is, two unsaturated units caused by ring-opening polymerization and one addition unit. Using proton NMR data of the polymers, the distribution of repeating units was calculated. A polymerization mechanism is proposed. The thermal stability of the obtained polymers is discussed.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 2613-2622 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cationic polymerization of 1,3-dioxepane (DOP) initiated with trifluoromethanesulfonic acid (I) in the presence of ethylene glycol (EG) was investigated. At sufficiently low concentration of the initiator ([I] 〉 0.01 mol/L vs. [EG] 〈 0.20 mol/L), the molecular weights of the obtained polyacetal oligodiols are controlled by the mole ratio of consumed DOP to initial EG. Gel-permeation chromatography studies revealed that the concentration of cyclic oligomers in the products are negligible. The mechanism of the polymerization was investigated by means of kinetic studies. The results showed that the polymerization proceeds according to the active chain end mechanism (ACF) in combination with the activated monomer mechanism (AM); thus the cyclic oligomer in the obtained polymer is reduced, and intermolecular chain transfer to EG in ACE is dominant. It was also demonstrated that as [DOP]2[I]/[EG] decreases the contribution of ACE to the polymerization decreases and that of AM increases. In addition, 1H and 13C NMR data illustrated that each macromolecule of polyDOP oligodiols contained one EG unit on average and that no EG end groups exist.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 1373-1381 
    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: A study of increasing the flexibility and lowering the internal stress of the cured epoxy resing was carried out by using polysiloxanes capped with functional groups and premaking polysiloxane particles with d = 1.1 μm and narrow distribution. Polysiloxanes capped with functional groups were prepared by the reaction of X-22-163B with bisphenol-A, hexanedioic acid, and decanedioic acid. Poly(dimethylsiloxane-b-arylester) was synthesized by the reaction of poly(dimethylsiloxane) (X-22-162C) with arylester oligomers. Polysiloxane particles were obtained by cycling the mixture of polysiloxanes containing a vinyl group and a≡Si-H group, respectively, emulsifier, and water in homogenizer. When oily polysiloxanes were used to improve the flexibility of epoxy resin, good compatibility of polysiloxanes with epoxy resion, and high molecular weight capped with epoxy group favor the formation of small-sized particles and homogeneous dispersion in the cured matrix. Comparisons were made among the epoxy resing modified with oily polysiloxanes capped with different functional groups. The results indicate that lightly crosslinked polysiloxane particles with d = 1.1 μm and narrow distribution have the greatest increase of elongation and biggest decrease of internal stress. The reason for this is discussed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 57 (1995), S. 895-901 
    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: A study on the increase of the flexibility and decrease of the internal stress of cured epoxy resins by addition of polysiloxane rubber particles grafted with and without glycidyl methacrylate (GMA) or methyl methacrylate (MMA) is reported. Polysiloxane latex was obtained by cycling a mixture of polysiloxane containing a vinyl group and a≡Si—H group, respectively, emulsifier, and water in a homogenizer. Graft polymerization of GMA (or MMA) on these rubber particles was performed in the latex under γ-ray irradiation of 60Co. The rubber particles were used to improve the flexibility of the epoxy resin. The particles grafted with GMA showed a homogeneous distribution in the matrix, better inducing and terminating craze. Comparisons were made among the particles grafted with MMA and various MMA—GMA or a series of GMA; the results indicated that the particles grafted with GMA (graft ratio = 10%) showed the greatest increase of elongation and decrease of internal stress. The factors influencing the toughness of the epoxy resin matrix are discussed. © 1995 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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