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  • 1
    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 Various lyotropic liquid crystalline polyesteramides were prepared from 1,3-bis(4-aminobenzoyloxy)benzene, p-phenylene diamine, and terephthalic acid by changing the ratio of amide to ester groups and were observed by using a cross polarized light microscope. The range of liquid crystalline phase becomes wider with increasing the portion of amide groups in a main chain because the chain rigidity becomes higher and the polymer-solvent interaction stronger. In the case of polyesteramides with flexible spacers, the polymer with one p-phenylene group between two ester groups does not form an anisotropic phase but the polymer with the same group between amide groups shows an anisotropy.
    Type of Medium: Electronic Resource
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  • 2
    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 miscibility behaviour of sulfonylated poly(2,6-dimethyl-1,4-phenylene oxide) of the different degree of sulfonylation blended with poly(styrene-co-maleic anhydride) or poly(α-methylstyrene-co-maleic anhydride) was studied. The critical degree of sulfonylation for phase separation in these blends was found to be 55 mole % and 66 mole %, respectively. The miscibility behaviour was analyzed on the basis of the mean field treatment and studied by DSC.
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  • 3
    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 coefficient of thermal expansion is measured for irradiated Polyvinyl Chloride (PVC) from 10K to 340K. The samples of PVC are irradiated, up to 500 Mrad in steps of 100 Mrad, in air at room temperature by using Co gamma rays with a dose rate of 0.3 Mrad/h. The PVC is an amorphous sample which is confirmed by X-ray diffraction. The coefficient of thermal expansion is found to decrease with radiation dose from 10K to 110K and it increaseswith radiation dose from 110K to 340K. The results are explained on the basis of radiation induced degradation of the sample.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 28 (1992), S. A4 
    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
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  • 5
    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 Methods to synthesize dimethylsiloxane oligomers and macromonomers with aromatic diamino function were studied. Telechelic oligomers having 4-aminophenyl groups on both ends of the molecule(1) were synthesized by the reaction of 4-[N,N-bis(trimethylsilyl)amino]phenyllithium with α,ω-dichlorooligodimethylsiloxane. Reaction of the lithium reagent with methyltrichlorosilane followed by methanolysis and successive hydrolysis gave methylbis(4-aminophenyl)silanol. Reaction of the silanol with oligodimethylsiloxane with mono-dimethylchlorosilyl function at one end of the molecule gave dimethylsiloxane oligomers having methylbis(4-aminophenyl)silyl function at one end of the molecule(2). Protection of the amino groups of bis(4-aminophenyl)methane as bis(trimethylsilyl)amino group, metalation of methylene group by butyllithium-N,N,N′,N′-tetramethylethylenediamine (TMEDA), followed by the reaction with mono-dimethylchlorosilyl-functionalized oligodimethylsiloxanes gave oligodimethylsiloxanes having bis(4-aminophenyl)methyl function at one end of the molecule(3). Polydimethylsiloxane macromonomers having bis(4-aminophenyl)methyl function were obtained by end-capping the living end of the polymerization of hexamethylcyclotrisiloxane(D3) by lithium bis[4-{bis(trimethylsilyl)amino}phenyl]methide with trimethylchlorosilane and removal of the protecting group.
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  • 6
    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 diphenylzinc-H2O and diphenylzinc-H2O-ButCl systems were used as catalysts for styrene polymerization in solution at various temperatures and solvents. The systems are greatly influenced by the molar ratio H2O/Ph2Zn, and the maximum catalyst activity, in both cases, was found at a molar ratio of 0.75. GPC results strongly suggest the presence of more than one active species. For Ph2Zn-H2O-ButCl system, in dichloromethane at-78°C with the molar ratio of H2O/Ph2Zn=0.75, the reaction is first order with respect to monomer with kp=2.45×10-3 Lmol-1sec-1.
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  • 7
    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 synthesis of novel telechelic monodispersed nonconjugated dienes from commercially available α, ω-dithiols and dienes is presented. The batch reaction produced a polydispersed. mixture separable with difficulty whereas a dropwise addition of dithiol onto an excess of α, ω-diene in the presence of peroxide led selectively and quantitatively to the addition product: diene-dithiol-diene.
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  • 8
    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 A series of thermotropic copoly(4,4′-biphenylene sebacate-co-eicosanedioate)s were prepared by melt polycondensation of 4,4′-biphenylene diacetate, sebacic acid and eicosanedioic acid. Their thermal transitions and liquid crystalline properties were investigated by DSC and polarized micrrocope. The copolyesters were found to exhibit a smectic phase, but no nematic phase was observed upon cooling. The smectic-isotropic transition temperature decreased as the content of eicosanedioate unit increased, and the corresponding transition heat did not change to a great extent. However, the crystalline-smectic transition temperature showed an eutectic behavior, and the crystalline-smectic transition heat was depressed considerably after copolymerization. The X-ray diffraction data of the copolyesters after thermal treatment were measured and compared with the thermal properties measured by DSC.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 28 (1992), S. 555-560 
    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 3-Vinylbenzothiophene was synthesized and its copolymerization with methyl methacrylate and n-butyl acrylate was investigated. The copolymerizations were performed according to an experimental design scheme and the results were analyzed using a nonlinear error-in-variables method. The 3-vinylbenzothiophene was found to be a reactive monomer with reactivity ratio values similar to those of 2-vinyl thiophene.
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  • 10
    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 hydrophilic monomers, 2-aminoethylmethacrylamide (AEMA), N,N-bis (2-hydroxypropyl) aminoethylmethacrylamide (HPAEMA) and N,N,N′-tris(2-hydroxypropyl) ethylenediamine methacrylate (HPEDM), were prepared through selective and reversible protection of ethylenediamine. Ethylenediamine was selectively protected by trimethylsilylation to give N,N,N′-tris-and N,N-bis(trimethylsilyl) ethylenediamine. Stoichiometric addition of methacryloyl chloride to N,N,N′-tris (trimethylsilyl) ethylenediamine gave exclusively N,N-bis (trimethylsilyl) aminoethylmethacrylamide (BTAEMA) in quantitative yield. Desilylation with methanol also produced AEMA in quantitative yield. Treatment of AEMA with propylene oxide produced HPAEMA monomer in 92.4% yield. N,N-Bis (trimethylsilyl) ethylenediamine was treated with propylene oxide, and desilylated to give 92.8% yield of N,N-bis(2-hydroxypropyl) ethylenediamine. Upon treatment with glycidyl methacrylate, HPEDM monomer was produced in 75.6% yield. The selective and reversible protection of ethylenediamine provides a convenient and efficient method for generating asymmetrically substituted ethylenediamine-based monomers.
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