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  • Articles  (11,576)
  • Springer  (11,576)
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  • 1992  (11,576)
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  • Articles  (11,576)
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  • 1990-1994  (11,576)
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  • 1
    Electronic Resource
    Electronic Resource
    Acid-catalyzed photoaromatization of poly(cyclohexadiene-1,2-diol) derivatives into polyphenylene (1992)
    Springer
    Polymer bulletin 28 (1992), S. 33-40 
    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 Substituted poly(cyclohexene)s, used as poly(phenylene) precursors, have been prepared by radical polymerization of cyclohexadiene-1,2-diol derivatives containing various leaving groups. The precursors were converted into poly(phenylene) either by curing at elevated temperatures or by deep-UV exposure in the presence of a photoacid generator. These reactions were investigated by both IR and UV analysis. Our results with the conversion of precursors into poly(phenylene) via photoaromatization suggest that polyphenylene precursors can be imaged by deep-UV microlithography (as a new class of photoimageable thermally stable polymers).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01045635
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  • 2
    Electronic Resource
    Electronic Resource
    Cationic polymerization of selected α- and β-substituted vinyl ethers (1992)
    Springer
    Polymer bulletin 28 (1992), S. 117-122 
    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 The cationic polymerization of various α- and β-substituted vinyl ethers, initiated by 1-iodo-1-(2-methylpropyloxy)ethane 1 and tetrabuty lammonium perchlorate (TBAP) was investigated. The polymerization of 2,3-dihydrofuran (DHF, 3a) in CH2Cl2 at -40°C proceeds via opening of the ethylenic double bond and yields polymers with narrow molar mass distributions and high glass transitions. The number average of molar mass increased linearly with conversion. Under these conditions, a controlled polymerization of two propenyl ethers (1-ethoxypropene 2a and 2-methoxypropene 2b) and two other cyclic unsaturated ethers (3,4-dihydro-2H-pyran 3b and 5-methyl-2,3-dihydrofuran 3c) could not be achieved. Either transfer reactions or the decomposition of 1 prevented the formation of high molar mass polymers of these vinyl ethers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299645
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  • 3
    Electronic Resource
    Electronic Resource
    Copolymerization behavior of 3-vinylbenzothiophene (1992)
    Springer
    Polymer bulletin 28 (1992), S. 555-560 
    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 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296046
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  • 4
    Electronic Resource
    Electronic Resource
    Stereoregular oligomers of methyl methacrylate (1992)
    Springer
    Polymer bulletin 28 (1992), S. 561-568 
    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 Isotactic (it-) and syndiotactic (st-) MMA oligomers from 19-mer to 29-mer could be isolated efficiently from it-PMMA ( $$\overline {DP}$$ = 28.6) and st-PMMA ( $$\overline {DP}$$ = 28.6) (sample load: 50 mg) by the SFC using a 10 mm i. d. x 250 mm column packed with silica gel. DP of each isolated oligomer was determined by FD mass spectroscopy, and the values agreed well with those calculated from the relative intensity of 1H NMR signals due to CH3O- and the terminal t-C4H9-groups. Glass transition temperature (T g) of the it-28-mer measured by DSC was 34.5°C, which was higher than that of the it-PMMA by 6.5°C. T g of both the it-and st-oligomers increased linearly with DP in the range of DP=20∼29. A 1: 1 mixture of the it- and st-27-mers annealed at 140°C showed an endothermic transition at 102.3°C which was attributable to melting of stereocomplex, whereas an annealed 1: 1 mixture of the it- and st-PMMAs had a much broader endotherm around 80∼140°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296047
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  • 5
    Electronic Resource
    Electronic Resource
    EPR investigations of the influence of N,N′-methylene-bisacrylamide (NNMBA) crosslinks on the coordination structure of Cu(II) complexes of poly (N-2-aminoethylacrylamide)s (1992)
    Springer
    Polymer bulletin 28 (1992), S. 585-591 
    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 The coordination structures of Cu(II) complexes of amino functions supported on polyacrylamides with varying extents of NNMBA-crosslinks were followed by EPR techniques. The geometry of the Cu(II) complexes changes with increasing crosslinking. The covalency of the Cu-N bond also depends on the extent of the NNMBA-crosslinking in the polymer-support.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296050
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  • 6
    Electronic Resource
    Electronic Resource
    Crosslinking effect on sorption and thermal stability by crosslinked poly(ethyleneimine) (1992)
    Springer
    Polymer bulletin 28 (1992), S. 601-606 
    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 The sorption behaviour of copper (II) and uranium (VI) ions on branched poly(ethylenimine) (BPEI) bridged with bifunctional crosslinkers (CR), 1-chloro-2,3-epoxypropane, 1,3-dibromopropane and 1,2-dibromoethane with various degress of crosslinks has been examined. The effect of crosslinking on the extent of sorption and thermal stability is reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296052
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  • 7
    Electronic Resource
    Electronic Resource
    Lyotropic mesophase formations of HPC/imogolite mixture (1992)
    Springer
    Polymer bulletin 28 (1992), S. 607-614 
    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 The mesophase formation was observed from the system of mixed organic polymer (hydroxypropyl cellulose) and inorganic polymer (imogolite) in acetic acid aqueous solution. The phase diagram of the mesophase formation was drawn as a function of imogolite content. The mesophase structure was found to change from the helicoidall arrangement of nematic sheets to the pile of pleated nematic sheets with increasing imogolite content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296053
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and rheological study of some maleic acid and fumaric acid stereoregular polyesters (1992)
    Springer
    Polymer bulletin 28 (1992), S. 621-626 
    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 First unsaturated polyester fibers were prepared starting from stereoregular, macromolecular poly(octamethylene fumarate). Fibers obtained from octamethylene copolyesters of fumaric and terephthalic acids manifested improved mechanical properties and higher melting points. All unsaturated polyester fibers prepared in the study, based on the homopolymer and on copolymers of fumaric acid, even those containing as low as 10% of fumaric acid residues, are able to be covalently bonded to an unsaturated polyester matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295963
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  • 9
    Electronic Resource
    Electronic Resource
    Reactive propylene oligomers (1992)
    Springer
    Polymer bulletin 28 (1992), S. 633-638 
    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 Propylene oligomers containing isopropenyl end group have been prepared by thermolysis of atactic polypropylene. The chain-end structures and the number-avarage isopropenyl chain end functionality was determined in the product by C-13 NMR spectroscopy. Molecular weight of the oligomers were between 300 and 1000, as characterized by GPC. Conditions leading to the formation of propylene oligomers with number-average isopropenyl chain end functionality of 1.0, have been worked out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295965
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  • 10
    Electronic Resource
    Electronic Resource
    Unusual addition by the thiol-ene photopolymerization (1992)
    Springer
    Polymer bulletin 28 (1992), S. 653-656 
    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 The photoaddition of aromatic dithiols (1) onto aliphatic alkenes (2a-2c) yielding polysulfides is studied. Polysulfides having anti-Markownikow and Markownikow moieties in the main chain are obtained by the reaction of dithiols (1) with ethyleneglycoldivinylether (2a). The unusual Markownikow orientation is explained on the basis of a radical cation intermediate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295968
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  • 11
    Electronic Resource
    Electronic Resource
    Preparation of monodispersed polymer-modified silica particles by radical polymerization using silica colloid and introduction of functional groups on the composite surface (1992)
    Springer
    Polymer bulletin 28 (1992), S. 663-668 
    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 Radical polymerizations of vinyl monomers using a initiator of 2,2′-azobis(2-amidinopropane) dihydrochloride on monodispersed silica colloid led to formation of spherical polymer/SiO2 composites, retained particle size. Addition of hydroxypropyl cellulose to the reaction system resulted in yielding excellent dispersible composites into ethanol by short period ultrasonic irradiation. The polymerization of styrene in the presence of mercapto-amine or carboxylic acid derivatives could successfully introduce amino or carboxyl group on the Poly(styrene)/SiO2 composite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295970
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  • 12
    Electronic Resource
    Electronic Resource
    Electrical conductance of some cellulose derivatives (1992)
    Springer
    Polymer bulletin 28 (1992), S. 689-695 
    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 The interrelation between the electrical conductance, σ and some chemically modified cellulose molecule produced through partial substitution of the hydroxyl groups by different groups namely, acetate, methoxyl, carboxymethyl and sodium carboxymethyl has been studied in the temperature ranges 283–333 k. The results show that σ of the examined samples change in the descending order: sodium carboxymethyl cellulose 〉carboxymethyl cellulose 〉methyl cellulose〉cotton cellulose〉cellulose acetate. The variable response of σ to the chemical modification and the physical changes of cellulose accompanying such modification has been discussed in terms of the molecular structure, chain flexibility and degree of polymerization of the examined samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295974
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  • 13
    Electronic Resource
    Electronic Resource
    On the polarity and donor-acceptor-properties of polysaccharides (1992)
    Springer
    Polymer bulletin 28 (1992), S. 697-702 
    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 Acidic parameters according to the GUTMANN's acceptor numbers (AN) of cellulose acetates and unmodified cellulose have been determined by means of the negatively solvatochromic probe dye Fe(phen)2(CN)2. Unmodified cellulose possesses a relatively high acceptor strength due to cooperative hydrogen bonds while increasing acetate contents in the polymer chain lower the acceptor strength. The dependence of AN on the acetate content can be used to estimate the degree of substitution (DS). Pecularities in the substitution interval (DS=0 to DS=1.5) are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295975
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  • 14
    Electronic Resource
    Electronic Resource
    Bending behavior of an electrically activated complex forming hydrogel (1992)
    Springer
    Polymer bulletin 28 (1992), S. 677-681 
    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 The complex forming poly[(ethylene glycol-co-proplene glycol)-g-acrylamide]: polyacrylic acid interpenetrating polymer network hydrogel is able to bend under electric field “stimuli”. pH, ionic strength gradients and voltage can influence it's bending degree. So we may improve the sample' “responsive” speed through manipulating those factor in the further study in order to put it into the biomedical application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295972
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  • 15
    Electronic Resource
    Electronic Resource
    Application of iniferters for obtaining composition homogenous copolymers (1992)
    Springer
    Polymer bulletin 28 (1992), S. 449-450 
    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 An original way of reducing composition heterogeneity has been proposed for copolymers obtained at high conversions. The main idea underlying this method consists in application as initiators of special compounds (iniferters) leading to alteration of the mechanism of polymer chain growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297338
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  • 16
    Electronic Resource
    Electronic Resource
    Molecular-mass distributions resulting from the homopolymerization of monoepoxides initiated by tertiary amines (1992)
    Springer
    Polymer bulletin 28 (1992), S. 459-465 
    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 A reaction scheme based on propagation and intramolecular chain transfer steps is proposed for the anionic homopolymerization of epoxides initiated by tertiary amines. Chain transfer regenerates a living chain and gives a dead chain with terminal vinilydene unsaturations and hydroxy groups. The possibility of generating phenols or substituted phenols is also considered. Molecular-mass distributions were predicted as a function of conversion by both kinetic and Monte Carlo methods. Predictions were compared with experimental results reported in the literature. The evolution of the number-average degree of polymerization could be reasonably predicted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297340
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  • 17
    Electronic Resource
    Electronic Resource
    Thermal expansion of irradiated polyvinyl chloride from 10 K to 340 K (1992)
    Springer
    Polymer bulletin 28 (1992), S. 481-487 
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    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297343
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  • 18
    Electronic Resource
    Electronic Resource
    Indexed in current contents (1992)
    Springer
    Polymer bulletin 28 (1992), S. A4 
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    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297346
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  • 19
    Electronic Resource
    Electronic Resource
    Synthesis of telechelic monodispersed diols (1992)
    Springer
    Polymer bulletin 28 (1992), S. 497-503 
    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 The synthesis of telechelic monodispersed diols produced from the radical telomerization of an excess of undecylenol with commercialy available α, ω-dithiols HSC2H4XC2H4SH (X=0, S or CH2) initiated by peroxides is presented. In each case, the diols were obtained selectively and quantitatively and they were characterized by both 1H and 13C NMR. Their physical characteristics (Tg, Tm and decomposition temperatures) were determined. Such compounds are thermally more stable than polydispersed telechelic commercially available diols.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296038
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  • 20
    Electronic Resource
    Electronic Resource
    Anionic polymerization of vinylsilanes (1992)
    Springer
    Polymer bulletin 28 (1992), S. 505-509 
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    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 anionic polymerization of dimethylphenylvinylsilane with sec-butyllithium/N,N,N′,N′-tetramethylethylenediamine (TMEDA) was investigated. The polymerization proceeded up to 100% yield and afforded the polymer having isomerized-structure units. The polymerization was accompanied by chain transfer reaction to the monomer and the polymerization rate in the presence of TMEDA was much lower than in the absence of TMEDA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296039
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  • 21
    Electronic Resource
    Electronic Resource
    Functionalization of a multiepoxy resin by methacrylic compounds and study of its thermal properties (1992)
    Springer
    Polymer bulletin 28 (1992), S. 627-632 
    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 Methacrylation of triglycidyl triphenyl methane (via methacrylic acid) has been done using three catalysts: dimethyl dodecyl amine (DMDA), tetrabutyl ammonium bromide (TBAB) and chromium (III) diisopropyl salicylate (Cr Dips). The reaction has been followed by epoxy colorimetric titration, CPG and 1H NMR. This study has shown the superiority of chromium catalysis because of its rapidity and ease of process. Then, these cured products (TACTIX and methacrylated TACTIX) show homogeneous Tg values which are higher than 200°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295964
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  • 22
    Electronic Resource
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    Phase transfer catalysis in the polycondensation processes (1992)
    Springer
    Polymer bulletin 28 (1992), S. 639-644 
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    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 Polyesters from 3,3′-bis(chloromethyl)oxacyclobutane and dipotassium isophthalate were obtained by phase transfer catalysis using different catalysts and solvents. The products were characterised by IR,1H-NMR and DSC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295966
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  • 23
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    Electronic Resource
    Polymerization by phase transfer catalysis (1992)
    Springer
    Polymer bulletin 28 (1992), S. 645-652 
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    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 Polycarbonates, polythiocarbonates, and polyesters from 1,1,3-trimethyl-3-(4′-hydroxy-phenyl)-4-indanol were synthesized using phase transfer conditions. THe effects of several catalysts and reactions times were evaluated by the yields and inherent viscosities. Phase transfer catalysis was not an efficient technique due to the rigid structure of the diphenol with the indanic group. The results were compared with that obtained with a diphenol having the same number of carbon atoms but forming an aliphatic side chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295967
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  • 24
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    Effects of 1,2,3-triphenylcyclopropene on radical polymerizations (1992)
    Springer
    Polymer bulletin 28 (1992), S. 657-662 
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    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 1,2,3-Triphenylcyclopropene (TPCP) is a powerful retarder for polymerizations of methyl methacrylate (MMA) and styrene initiated by benzoyl peroxide or azobisisobutyronitrile. End-groups in polymers of MMA were studied by 13C-NMR spectroscopy and also, in the case of the peroxide, by using radioactive initiator. It was shown that, towards the benzoyloxy and 1-cyano-1-methylethyl radicals, the reactivity of TPCP exceeds that of MMA by factors of about 60 and three respectively at 60°C. TPCP can be used to introduce into polymers end-groups of special types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295969
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  • 25
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    Solvent effect on the complex formation of polyvinylpyrrolidone and polymonomethyl itaconate (1992)
    Springer
    Polymer bulletin 28 (1992), S. 669-676 
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    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 influence of solvent on polyvinylpyrrolidone (PVP) and polyitaconic acid monomethylester (PMMI) sterecomplex formation was studied by means of laser light scattering and viscometry. Several phase changes were observed, from homogeneous solution to precipitates and gels. Responsible of this behaviour are hydrogen bonding, Coulombic forces, or hydrophobic interaction in aqueous medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295971
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  • 26
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    Easy use of Lewis and Mayo's rule to determine monomer conversion-rates in cotelomerization (1992)
    Springer
    Polymer bulletin 28 (1992), S. 703-707 
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    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 Lewis and Mayo's rule, used so far for the determination of r1 and r2, is presently applied for the simultaneous determination of partial monomers conversions α1 and α2; whereas the integration of the Skeist's rule gave global conversion α only. An experimental verification is performed for the cotelomerization of MMA and maleic anhydride with dodecyl mercaptan as telogen, and it gives a very good correlation.
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    URL: http://dx.doi.org/10.1007/BF00295976
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  • 27
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    A striking observation on the fluorescence of a twisted intramolecular charge transfer (TICT) molecule used to probe polymer dynamics in the bulk state (1992)
    Springer
    Polymer bulletin 28 (1992), S. 709-715 
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    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: Abstract An anomalous effect on the twisted intramolecular charge transfer (TICT) phenomenon of 4-(N,N-dimethylamino) benzonitrile (DMABN) dissolved in elastomers such as poly(propylene oxide), poly(ethylene oxide) has been observed. Under irradiation, the normal fluorescence of DMABN in these matrices has been found to increase strongly while the emission arising from the TICT state decreases slightly.
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    URL: http://dx.doi.org/10.1007/BF00295977
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    The thermal polymerisation of a diacetylenic liquid crystal (1992)
    Springer
    Polymer bulletin 29 (1992), S. 661-668 
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    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 In this paper, the polymerisation of a conjugated liquid crystalline diacetylene is reported. The structure of the polymer is discussed in relation to results from spectroscopic studies and molecular weight determinations. The polymer has a backbone structure analogous to that of other polydiacetylenes.
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    URL: http://dx.doi.org/10.1007/BF01041152
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    “Liquid-cristalline” gels of polyamide networks with stiff segments and flexible junctions (1992)
    Springer
    Polymer bulletin 29 (1992), S. 675-679 
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    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 preparation of a novel family of “liquid-crystalline” polyamide network gels is described. In these networks, the segments are stiff and longer than the critical axial ratio for mesomorphic behavior. The junctions are trifunctional and flexible. The gels are intensely birefringent in the relaxed nascent state, unlike fully rigid or fully flexible gels. The birefringence of the present gels is clearly associated with the coexistence in them of both long, stiff mesogenic segments and flexible trifurcated junctions. Thermal studies of the gels indicate very strong attractive interactions between the networks and the solvent.
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    URL: http://dx.doi.org/10.1007/BF01041154
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    Polyisobutylene-containing block polymers by sequential monomer addition (1992)
    Springer
    Polymer bulletin 29 (1992), S. 697-704 
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    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: Abstract Novel poly(acenaphtylene-b-isobutylene-b-acenaphtylene) (PAc-PIB-PAc) triblock copolymers exhibiting thermoplastic elastomer (TPE) properties have been prepared. The synthesis involved the addition of acenaphtylene (Ac) to living polyisobutylene dications (⊕PIB⊕) obtained by living isobutylene (IB) polymerization induced by the dicumyl methyl ether (DiCumOMe)/TiCl4 initiating system at-80°C. The triblocks contain very short polyacenaphtylene (PAc) blocks (Mn≈9,000) and consequently yield very soft, low modulus TPEs. Efforts to develop conditions for the living carbocationic polymerization (LC⊕Pzn) of Ac have failed.
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    URL: http://dx.doi.org/10.1007/BF01041157
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    Cyanoethylation of cyclopentadiene: Isolation of penta- and hexa(β-cyanoethyl)cyclopentadiene and an unexpected acrylonitrile polymer (1992)
    Springer
    Polymer bulletin 27 (1992), S. 389-394 
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    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 cyanoethylation of cyclopentadiene was examined under a variety of reaction conditions. Approximately 9% of cyclopentadiene was converted to the desired hexa(β-cyanoethyl)cyclopentadiene when the amount of acrylonitrile to cyclopentadiene was increased from 2 to 7 equivalents under phase transfer conditions. The low conversion is due to competitive formation of various unreactive side-products. For example, termination leading to less-highly substituted products was confirmed by isolation of crystalline 1,1,2,3,4-penta(β-cyanoethyl)cyclopentadiene. Another side product isolated and characterized by 13C NMR was an oligomer of acrylonitrile attached to hexa(β-cyanoethyl)cyclopentadiene; the anion (at a β-alkyl position) of the latter apparently acted as anionic initiator. Attempts to induce thermal polymerization and cyclotrimerization of the pendent cyano groups of hexa(β-cyanoethyl)cyclopentadiene were unsuccessful even with added Lewis acid catalysts. Reduction to the hexaamine was only partially successful.
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    Butadiene polymerisation using ternary neodymium-based catalyst systems (1992)
    Springer
    Polymer bulletin 27 (1992), S. 407-411 
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    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 Ternary catalyst systems for the polymerisation of 1,3-butadiene to high cis content were studied. The systems Nd(carboxylate)3/tert-butyl chloride/diisobutylaluminium hydride (carboxylate = naphthenate, versatate) were studied with respect to the order of catalyst component addition on catalyst activity and polymer characteristics. Stable catalysts which give relatively narrow molecular weight distribution are give by component addition order Nd(carboxylate)3+diisobutylaluminium hydride+tert-butyl chloride. Less stable systems giving broader polymer molecular weight distributions are given by addition orders tert-butyl chloride+diisobutylaluminium hydride+Nd(carboxylate)3 and Nd(carboxylate)3 +tert-butyl chloride+diisobutylaluminium hydride.
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    Esterolyses of p-nitrophenyl esters catalyzed by dialkylaminopyridines attached to polyorganosiloxane (1992)
    Springer
    Polymer bulletin 27 (1992), S. 413-420 
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    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 present study describes the preparation of polyorganosiloxanes containing dialkylaminopyridines in their side chains (POS-DAAPs) and the use of them as catalysts for esterolyses of p-nitrophenyl esters of CH3(CH2) n COOH (n=0–5). The POS-DAAPs (4, 5) were prepared from poly[(3-chlorocarbonylpropyl)methylsiloxane] (PCCPMS, 1) and two pyridine derivatives, such as 4-[(2-hydroxyethyl)methylamino]pyridine (HEMAP, 2) and 4-[4-(2-hydroxyethyl)piperidino]pyridine (HEPP, 3). Pyridyl groups of POS-DAAPs 4 and 5 were partially quaternized with dimethylsulfate (6, 7) in order to carry out esterolysis in homogenious systems. The esterolyses were examined in methanol/tris(hydroxymethyl)-aminomethane-hydrochloric acid buffer solution (vol. ratio 2/1, pH of buffer solution: 7.5) and analyzed following Michaelis-Menten like kinetics. The second-order rate constants (k 2/K m) of the esterolyses catalyzed by POSs 6 and 7 were 22–38 fold values of those catalyzed by the corresponding monomolecular catalysts 2 and 3. In addition, the effects of POSs were discussed from the kinetic, thermodynamic, and activation parameters.
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    Effect of ethyl aluminium sesquichloride on the specificity of the reactions of 1-methyl-1-methoxycarbonylethyl radical (1992)
    Springer
    Polymer bulletin 27 (1992), S. 425-428 
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    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 Copolymerizations of styrene and methyl methacrylate (MMA) have been carried out with azo-bis-(methyl isobutyrate-α-13C) (AIBMe-α-13C) as initiator and in the presence of ethyl aluminium sesquichloride (EASC). The specificity of the 1-methyl-1-(methoxycarbonyl)ethyl radical (I) for reaction with styrene over MMA is substantially enhanced by the presence of very low concentrations of EASC. This behaviour is consistent with the involvement of a complexes radical and suggests that such species may play an important role in Lewis acid induced alternating copolymerization.
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    The influence of H-bonding in liquid crystalline polyazomethine ethers (1992)
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    Polymer bulletin 27 (1992), S. 429-434 
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    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 model compound 1,4-bis(anisylimido)benzene has been characterized by solution and CP/MAS 13C NMR to assist in the characterization of liquid crystalline polyazomethines (PAM) based on the same mesogenic structure. Thermal behavior of several homologs of this PAM series have been compared before and after treatment with the end capping agent benzaldehyde. The results suggest that PAM oligomers containing large quantities of amine termination can strongly effect thermal behavior at constant oligomer molecular weight.
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    A new technique for the study of reactive species generated during the initial stages of polymer photodegradation (1992)
    Springer
    Polymer bulletin 27 (1992), S. 421-424 
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    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 low temperature ESR technique has been developed for the observation of free radical intermediates generated in clear polymer films during photolysis by UV light under nitrogen. The technique is simple and reproducible, and can be used for polymers having glass transition temperatures at or about room temperature without the need to employ spin traps. The generation of free radicals can be monitored and quantified during exposure, and the radical yields obtained can then be correlated with the chemical structure of the polymer to provide a rapid predictive evaluation of the exterior durability of the polymer.
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    Electrical conductivities and electron spin resonance spectra of polyaniline salts with different counteranions (1992)
    Springer
    Polymer bulletin 27 (1992), S. 435-439 
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    Notes: Summary Electrical conductivities and ESR spectra were obtained for polyaniline salts that contained different counter anions. The electrical properties were markedly different from one salt to another, although the concentrations of counteranions were almost identical. The ESR spectra showed that different types of unpaired electrons were created upon protonation. There was a close correlation between the charge-transport property and the nature of unpaired electrons created upon protonation.
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    Metal-containing intermacromolecular complexes: Electrochemical and viscometric studies in DMF-methanol mixture (1992)
    Springer
    Polymer bulletin 27 (1992), S. 451-457 
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    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 Multicomponent intermacromolecular complexes have been prepared from some typical phenolic copolymers with a non-ionic polymer (e.g. PVP), and a polyelectrolyte (e.g. PAA). Some transition metal ions (e.g. Cu(II) and Ni (II)) have been incorporated in the complex through its unreacted co-ordinating groups. The formation of these complexes has been studied by several techniques, such as viscometry, conductometry, potentiometry, IR and UV spectrophotometry. A scheme has been presented to explain the mode of interaction of the various components.
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    Phase transition in swollen gels (1992)
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    Polymer bulletin 27 (1992), S. 577-583 
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    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 swelling and mechanical behaviour of networks of copolymers of acrylamide, methylenebisacrylamide and sodium 2-(2-carboxybenzoyloxy)ethylmethacrylate (mole fraction of salt x s =0–0.2) in water-acetone mixtures was investigated. In the range x s ≥0.01 phase transition (collapse) was observed, with both the extent of the collapse and the critical acetone concentration in the mixture at collapse, a c , increasing with increasing concentration of the salt. A comparison between these results and those obtained for networks with a quaternary ammonium salt led to a conclusion that an exchange of the positive charge of the ammonium salt (N⊕Cl⊖) for the negative charge of the sodium salt (COO⊖Na⊕) in the side chain decreases the critical content of salt necessary for the collapse, X s c , from 0.03 to 0.01, and the collapse takes place at lower concentrations of acetone. The collapse may also take place in a mixed solvent waterethanol; the dependence of network swelling on the concentration of ethanol is roughly the same as that on the concentration of acetone.
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    Syntheses of polysilanes having cyclodisilazane units in the backbone (1992)
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    Polymer bulletin 27 (1992), S. 607-613 
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Polysilanes containing cyclodisilazane units in the backbone were synthesized by the modified Wurtz-type coupling of available dichlorosilanes with N,N′-bis (chlorodimethylsilyl)tetramethylcyclodisilazane in the mixture of solvents. The effect of solvent additives on the polymerization process was examined. These polymers are soluble in common solvents and very easily handled by molding or casting.
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    Preparation of stereoregular block copolymer comprising isotactic PMMA and polyisobutylene blocks and its characterization (1992)
    Springer
    Polymer bulletin 27 (1992), S. 615-622 
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    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 triblock copolymer of isotactic(it)-poly(methyl methacrylate) (PMMA) and polyisobutylene (PIB), it-PMMA-block-PIB-block-it-PMMA, was prepared by anionic polymerization of triphenylmethyl methacrylate initiated with α, ω-dilithiated PIB diisobutyrate in tetrahydrofuran at -78°C, and subsequntt hydrolysis and methylation with diazomethane. Molecular weight distribution of the triblock copolymer was narrow, and the stereoregularity of the PMMA block was highly isotactic. Proton spin-lattice relaxation times of the block copolymer in acetone-d6, which is non-solvent for PIB but dissolves the block copolymer, indicate the aggregation of the copolymer through PIB block. Stereocomplex formation between the it-block copolymer and syndiotactic(st)-PMMA-block-PIB-block-st-PMMA was also studied.
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    An investigation of the synthesis and thermal stability of poly(dl-lactide) (1992)
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    Polymer bulletin 27 (1992), S. 623-629 
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    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 and thermal degradability of poly (DL-lactide) were investigated. Key factors affecting the polymer molecular weight were found to be monomer recrystallization, initiator concentration and the vacuum level during drying/sealing of the polymerization reaction ampoule. It was found that poly (DL-lactide) is thermally unstable above its melting temperature. Monomer recrystallization, polymer precipitation and a low initiator content of the polymer significantly inhibited the rate and extent of thermal degradation.
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    Thermoplastic elastomers by sequential monomer addition (1992)
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    Polymer bulletin 27 (1992), S. 631-636 
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The living carbocationic polymerization (LC⊕ Pzn) of p-methylstyrene (pMeSt) was achieved by the use of the 2-chloro-2,4,4-trimethylpentane (TMPCl)/TiCl4 initiating system in the presence of triethylamine (Et3N) electron donor in CH3Cl/nC6H14 mixed solvent at-80°C. Next, the synthesis, characterization, and some physical-mechanical characteristics of a series of poly (p-methylstyrene-b-isobutylene-b-p-methylstyrene) (PpMeSt-PIB-PpMeSt) triblocks is described. The latter synthesis involved two steps in one reactor: 1) The generation of diliving polyisobutylene dications (⊕PIB⊕) by the dicumyl chloride (DiCumCl)/TiCl4 system under similar conditions followed by 2) The addition of pMeSt and growth of living PpMeSt⊕ cations. The PpMeSt-PIB-PpMeSt triblocks are soft thermoplastic elastomers (TPEs).
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    A new class of small band gap organic polymer conductors (1992)
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    Polymer bulletin 29 (1992), S. 119-126 
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Polysquaraines and polycroconaines have been synthesized. They form a new class of polymers with a small band gap, down to 0.5 eV. The small gap arises from the regular alternation of strong donor and acceptor-like moieties in a conjugated backbone.
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    Reactive propylene oligomers (1992)
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    Polymer bulletin 29 (1992), S. 135-138 
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    Notes: Summary Propylene oligomers with primary-OH, tertiary-0H andα,β-di-OH end groups have been prepared by converting the isopropenyl-ended oligomers with hydroboration-oxydation, oxymercuration-demercuration and performic acid hydroxylation reactions, respectively.
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    Complexation of the propagating chain-end in living cationic polymerization (1992)
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    Polymer bulletin 29 (1992), S. 127-134 
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    Notes: Summary Kinetics of polymerization has been studied in the system isobutylene/dicumylmethylether/BCl3 (CH2Cl2, −80°C) in the presence of dimethyl sulphoxide added as electron donor in a broad concentration range. The apparent propagation rate constant showed a DMSO concentration dependence typical for complex equilibria. At a given DMSO concentration, the apparent rate constant decreases with increasing initial monomer concentration showing a seemingly zero-order propagation. A possible explanation of this phenomenon is the formation of a chain-end/monomer complex. Equilibrium and propagation rate constants have been determined.
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    Generation of finely-divided nickel particles in a protective medium and their use as high-activity catalysts (1992)
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    Polymer bulletin 29 (1992), S. 343-348 
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    Notes: Summary In this technique, a relatively unreactive substance is transformed into a catalytically-active one within a protective environment. In this illustrative case, nickel formate was dissolved in a solution of poly(ethylene oxide) (PEO) in ethylene glycol, and then thermally decomposed in-situ to form finely-divided nickel particles. The mixture was dried, thereby protecting the nickel by encapsulating it in the polymer matrix. The distribution and the dispersity of nickel particles were investigated by electron microscopy. Upon adding portions of the catalyst-containing polymer to a reaction medium, the protective polymer dissolves, which releases the nickel particles and permits them to catalyze the reaction. In this particular case, the Ni-PEO sample was evaluated for the hydrogenation of an olefin, and found to be a highly efficient catalyst.
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    Determination of the substitution patterns of cellulose methyl ethers by HPLC and GLC-comparison of methods (1992)
    Springer
    Polymer bulletin 29 (1992), S. 349-356 
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    Notes: Summary The substitution patterns of methyl cellulose as well as of a thexyldimethylsilyl cellulose after permethylation were determined by hydrolysis and separation of the resulting partially methylated glucoses without further derivatization by h.p.l.c.. On an amine-modified silica column the solutes get separated into glucose, 2,3,6-tri-O-methyl glucose and the groups of mono-O-methyl-and di-O-methyl glucoses. A chromatographic run on a reversed-phase column enables the identification of the single mono-O-methyl- and di-O-methyl glucoses. In this way, a determination of both the average degree of substitution and the substitution pattern of cellulose derivatives is possible. Comparison of the results with those obtained by standard methylation analysis including g.l.c.-m.s. proves the correctnes of the method employed.
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    Amidification of poly(styrene-co-maleic anhydride) with amines in tetrahydrofuran solution: A kinetic study (1992)
    Springer
    Polymer bulletin 29 (1992), S. 357-363 
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The kinetics of the reaction between a styrene-maleic anhydride copolymer (SMA) and amines was investigated in tetrahydrofuran solution between 0°C and 40°C. This reaction converts the maleic anhydride (MA) into the corresponding amide-acid, while the consecutive reaction of the generated acid with amine forming a diamide or transformation of the acid-amide into the imide was not observed. The amine reactivity follows the order: 1-octylamine〉 〉1-methyl hexylamine〉 〉1,1-dimethyl propylamine or dibutylamine, demonstrating that the amine reactivity depends, to a large extent, upon its steric hindrance. This reaction is reversible as shown by IR at high temperatures, but the reverse reaction was undetectable between 0 and 40°C. The overall reaction involves spontaneous and autocatalytic reactions, and the overall reaction rate can be written as:-d[MA]/dt=k0[MA][-NH2]+k1[MA][-NH0]2. In the case of 1-octylamine below 0.02 M, the spontaneous reaction dominates (i.e, k0〉 〉k1[-NH2]).
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    Chemiluminescence of polyethylene induced by UV irradiation (1992)
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    Polymer bulletin 29 (1992), S. 369-375 
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    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 chemiluminescence (CL) of polyethylene (PE) film induced by UV irradiation was investigated. CL parameter, I0, which indicates the oxidation rate under UV irradiation was obtained from a kinetic analysis. The I0 was found to be valuable to evaluate the durability of PE films.
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    Intramolecular triplet energy migration in poly(2-vinylnaphthalene) and poly(naphthylalkyl methacrylate)s in solid solution: Effects of side chain length (1992)
    Springer
    Polymer bulletin 29 (1992), S. 365-367 
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    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 effect of side chain length on intramolecular triplet energy migration of naphthalene containing polymers was investigated by a delayed fluorescence (DF) spectroscopy for the solid solution of the polymers. The degree of triplet energy migration depends strongly on whether the chromophores are directly attached to the main chain or not.
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    A preliminary analysis of the 300 MHz1H-NMR spectra of poly(4-bromo-2-vinylthiopene) and poly(5-bromo-2-vinylthiopene) (1992)
    Springer
    Polymer bulletin 29 (1992), S. 377-384 
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    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 300 MHz1H-nmr spectra of poly(5-bromo-2-vinylthiophene) and poly(4-bromo-2-vinylthiophene) are presented and analyzed in terms of polymer stereochemistry. In both cases, the spectra could be explained in terms of the polymers having a Bernoullian, atactic stereochemistry.
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    ESR study of the radical polymerization of styrene (1992)
    Springer
    Polymer bulletin 29 (1992), S. 385-392 
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    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 absolute rate constant of propagation (kp) in styrene polymerization was determined on the basis of ESR detection of the polymer radical in the temperature range of 0 to 130°C. The Arrhenius plot of kp gave a good linear relationship and the activation energy of the propagation was evaluated to be 39.7 KJ/mol. The termination rate constants over the same temperature range were also obtained by using the kp values according to the standard kinetics of radical polymerization. Apparent activation energy of the termination was estimated to be 15.6 KJ/mol.
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    Erratum (1992)
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    Polymer bulletin 29 (1992), S. 595-595 
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    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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    URL: http://dx.doi.org/10.1007/BF00296723
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    Content to volume 270 (1992)
    Springer
    Polymer bulletin 29 (1992), S. A3 
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    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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    URL: http://dx.doi.org/10.1007/BF00296724
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    The elastic behaviour of weakly ionic gels (1992)
    Springer
    Polymer bulletin 29 (1992), S. 587-594 
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    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 elastic modulus of polyacrylamide-acrylic acid hydrogels is studied in a wide range of swelling degrees. The modulus does not follow the concentration dependence predicted by the rubber elasticity theory. At low swelling degrees this can be attributed to the constrained state (non-phantom behaviour) of the network chains. The reason for the increase of modulus at nigh swelling degrees is seen in the finite extensibility and topological entanglements of the chains. A theory including these effects is proposed and verified by experiment.
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    Poly(1,3-cyclohexadiene-1,4-diyl) (1992)
    Springer
    Polymer bulletin 29 (1992), S. 597-603 
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    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 Dehalogenation polycondensation of 1,4-diiodo-1,3-cyclohexadiene with zerovalent nickel complex gives a new π-conjugated polymer, poly(1,3-cyclohexadiene-1,4-diyl) PCyh. A copolymer constituted of 1,3-cyclohexadiene-1,4-diyl and 1,4-cyclohexadiene-1,4-diyl is also obtained by a similar method. The black color of PCyh indicates the presence of extensive π-conjugation along the polymer chain presumably due to takings-trans conformation of PCyh. PCyh is unstable and oxidized under air. IR and CP-MAS13C-NMR spectra of PCyh are reasonable for the structure.
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    Synthesis of new maleimide monomers having a perfluoroaliphatic side chain and study of their copolymerization with vinelethers (1992)
    Springer
    Polymer bulletin 29 (1992), S. 605-612 
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    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 fluorinated maleimide has been prepared from fluorinated diol with monofluoronitrobenzene. All the intermediates have been perfectly characterized by N.M.R. The study also describes the synthesis of a copolymer from a commercial vinyl ether and this maleimide. Copolymerization is not perfectly alternated as we could expect but the copolymer exhibits a glass transition equal to 165°C.
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    Reactions of organoboron polymers prepared by hydroboration polymerization (1992)
    Springer
    Polymer bulletin 29 (1992), S. 617-624 
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    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 Organoboron polymers were prepared by hydroboration polymerization between various dienes and thexylborane. These polymers were reacted with α-furyllithium followed by the treatment with acetic acid and then by the oxidative treatment to give the corresponding polyalcohols having primary and tertiary hydroxyl groups. The structures of the polyalcohols obtained were characterized by1H-NMR compared with that for model compound, which was prepared by the reaction of dioctylthexylborane with α-furyllithium. These conversions from organoboron polymers to polyalcohols include the migrations of two polymeric chains from boron atom to carbon and the ring-opening of furan ring.
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    Synthesis and reactivity of monodisperse prepolymers with blocked isocyanate end groups (1992)
    Springer
    Polymer bulletin 29 (1992), S. 613-616 
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    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 We describe the synthesis of monodisperse prepolymers containing one or two blocked isocyanate groups on the chain extremities. The prepolymers containing blocked isocyanate in one end and hydroxyl group in the other end are obtained by chemical transformation of undecylenic acid to acid chloride. This later was converted to the isocyanate by the CURTIUS reaction and blocked with nonyl-phenol. Finally the blocked isocyanate was telomerized with mercapto-ethanol. The resulting product is deblocked at T=105°C. By action of pure 2.4 T.D.I. (Tolylene diisocyanate) on the later product, we obtain a product containing blocked isocyanate end groups. The removal of the blocking agent could be effected at 100°C or less depending on the compound used to remove the blocking agent (amine).
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    Cyclopolymerization of 4,4-diphenoxy-1,6-heptadiyne by transition metal catalysts (1992)
    Springer
    Polymer bulletin 29 (1992), S. 625-632 
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    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 Cyclopolymerization was carried out by various catalyst systems. MoCl5-based catalyst systems are more effective for the polymerization of 4,4-diphenoxy-1,6-heptadiyne than WCl6-based catalyst systems. Polymerization of 4,4-diphenoxy-1,6-heptadiyne leads to soluble, purple colored polymer with number average molecular weight (Mn) of 3.6x104-5.2x104.1H- and13C-MNR, IR,and UV-visible spectra of the resulting polymer indicated that poly(4,4-diphenoxy-1,6-hepatadiyne) possesses a polyene structure presumably with cyclic recurring units in the polymer backbone. Poly(4,4-diphenoxy-1,6-heptadiyne) had good thermal and oxidative stability, and good solubility in organic solvents. The electrical conductivity of iodine-doped polymer was 10−3-10−2 S/cm.
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    Thermotropic liquid crystalline block copolyesters with PET as flexible spacers (1992)
    Springer
    Polymer bulletin 29 (1992), S. 633-638 
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    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 PET oligomers with different degrees of polymerization containing PHB as end groups were synthesized by melt condensation of bis(2-hydroxyethyl) terephthalate (BHET) in the presence of ethylp-hydroxybenzoate (EtPHB). Coupling the oligomers with terephthaloyl chloride, a series of block copolymers with identical triad aromatic ester “hard” segments as mesogen and different lengths of PET “soft” segments as spacer were obtained. Observation with a cross-polarized optical microscope shows that these copolymers are thermotropic in a certain range of the spacer length (n). Asn increases, the melting point (Tm) of the copolymer also increases, following the increasing molecular weight. The isotropic transition temperature (Ti) and the LC phase range (ΔT), on the other hand, decrease with the increasingn. Whenn exceeds a critical value, the LC phase disappears.
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    Absolute rate constants for radical-monomer reactions (1992)
    Springer
    Polymer bulletin 29 (1992), S. 647-652 
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    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 method is described for determining the absolute rate constants for the first few propagation steps in radical polymerization. The procedure involves a product analysis of the oligomeric alkoxyamines formed when an initiator is decomposed in monomer containing a very low concentration of a nitroxide radical scavenger. The method is illustrated with analysis of data for methyl acrylate. The rate constants for the first two propagation steps for polymerization of this monomer,k p(1) andk p(2), are at least an order of magnitude greater thank p(average). Values of the absolute rate constants for reactions of phenyl and primary alkyl radicals with methyl acrylate are also estimated.
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    Influence of the nature of monomers on the activity of supported titanium catalysts in the α-olefin polymerization (1992)
    Springer
    Polymer bulletin 29 (1992), S. 639-646 
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Ethylene and propylene co-polymerization and sequential polymerization with high activity supported titanium catalysts were studied. Specific rate of homopolymerization and copolymerization constants for ethylene and propylene were determined by using the derived values of the solubility constants for monomers in nascent polymers. The reason of the increased rate of co-polymerization upon enriching the monomers mixture with propylene, the effect of activation of ethylene polymerization upon preliminary polymerization of propylene may be in the increasing number of active sites due to enlarged content of amorphous phase in the nascent polymer product.
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    Flow development of xanthan solutions in capillary rheometers (1992)
    Springer
    Rheologica acta 31 (1992), S. 83-93 
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    ISSN: 1435-1528
    Keywords: Capillary rheometer ; xanthan solutions ; Bagley correction ; slip development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Flow experiments through capillaries with 0.2% xanthan in aqueous solution and 0.1 N NaCl brine were carried out to study the influence of the molecular conformation on the flow development at relatively low shear rates, from 20s−1 to 400s−1. Capillaries with a wide range of length-to-diameter ratios, L/D = 4.5 to 1015 were used. The apparent viscosity as a function of L/D at a constant shear rate shows a continuous decrement of the viscosity as L/D increases, until an asymptotic value is reached. The decrement in the apparent viscosity is partially explained in terms of slip. It was found that slip is a function of L/D as well as shear stress, i.e., slip develops during flow, thus inducing spatial anisotropy in the fluid until a stable state is reached. However, the substantial difference in apparent viscosity between short capillaries and capillaries longer than 300 D may be attributed to dominant elongational flow due to the contraction in the small capillaries and slip in long capillaries. The flow in a sufficiently long capillary can be divided in four regions rather than three, as is usually assumed. In the first region, which corresponds to the entry, elongational and shear flow coexist and elongational flow dominant. In the second region, end effects and slip development are coupled. In the third region the flow is fully developed and end effects are negligible. However, the fluid shows physical characteristics different from those of the fluid at rest, as a consequence of prior slip development. The fourth zone is the exit region in which the velocity rearranges due to the change of boundary conditions. The length of each region depends on the conformation of the macromolecules and shear rate. In addition, it was found that the stiffness of xanthan increases with the increase of the ionic strength. Finally, a performance of Bagley's analysis in the whole range of L/D studied showed that the use of the Bagley correction is not a reliable way to correct for end effects when the flow is not fully developed and/or in the presence of slip.
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    Using regularization methods for the determination of relaxation and retardation spectra of polymeric liquids (1992)
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    Rheologica acta 31 (1992), S. 161-174 
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    ISSN: 1435-1528
    Keywords: Viscoelastic fluid ; relaxation spectrum ; retardation spectrum ; Tikhonov regularization
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The application of Tikhonov regularization to the determination of relaxation and retardation spectra of viscoelastic fluids is discussed using simulated and real experimental data. It is thereby shown that with this method consistent results for relaxation and retardation spectra can be obtained from experimental data for different material functions. Furthermore, the differences between the most frequently used variants of Tikhonov regularization and the maximum entropy method are discussed. For most calculations the program FTIKREG has been used, which is an especially fast and reliable implementation of Tikhonov's regularization method.
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    Driven torsion pendulum for measuring the complex shear modulus in a steady shear flow (1992)
    Springer
    Rheologica acta 31 (1992), S. 194-205 
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    Keywords: Superimposed oscillatory shear ; complex shear modulus ; torsion pendulum ; nearly viscometric flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract To investigate the viscoelastic behavior of fluid dispersions under steady shear flow conditions, an apparatus for parallel superimposed oscillations has been constructed which consists of a rotating cup containing the liquid under investigation in which a torsional pendulum is immersed. By measuring the resonance frequency and bandwidth of the resonator in both liquid and in air, the frequency and steady-shear-rate-dependent complex shear modulus can be obtained. By exchange of the resonator lumps it is possible to use the instrument at four different frequencies: 85, 284, 740, and 2440 Hz while the steady shear rate can be varied from 1 to 55 s−1. After treatment of the theoretical background, design, and measuring procedure, the calibration with a number of Newtonian liquids is described and the accuracy of the instrument is discussed.
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    Stability of Couette flow of liquids with power law viscosity (1992)
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    Rheologica acta 31 (1992), S. 264-273 
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    ISSN: 1435-1528
    Keywords: Flow stability ; Couette flow ; Taylor vortices ; power law viscosity
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The stability of the Couette flow of the liquid with the power law viscosity in a wide annular gap has been investigated theoretically in this work with the aid of the method of small disturbances. The Taylor number, being a criterion of the stability, has been defined using the mean apparent viscosity value in the main flow. In the whole range of the radius ratio, R i /R o and the flow index, n, considered (R i /R o ≥ 0.5, n = 0.25–1.75 ), the critical value of the Taylor number Ta c is an increasing function of the flow index, i.e., shear thinning has destabilizing influence on the rotational flow, and dilatancy exhibits an opposite tendency. In the wide ranges of the flow index, n 〉 0.5, and the radius ratio, R i /R o 〉 0.5, the wide-gap effect on the stability limit is predicted to be almost the same for non-Newtonian fluids as for Newtonian ones. The ratio on the critical Taylor numbers for non-Newtonian and Newtonian fluids: Ta c (n) and Ta c (n = 1) obey a generalized functional dependence: Ta c (n)/Ta c (n = 1) = g(n), where g(n) is a function corresponding to the solution for the narrow gap approximation. Theoretical predictions have been compared with experimental results for pseudoplastic liquids. In the range of the radius ratio R i /R o 〉 0.6 the theoretical stability limit is in good agreement with the experiments, however, for R i /R o 〈 0.6, the critical Taylor number is considerably lower than predicted by theory.
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    Generalized Cole-Cole behavior and its rheological relevance (1992)
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    Rheologica acta 31 (1992), S. 309-322 
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    ISSN: 1435-1528
    Keywords: Linear-viscoelasticity ; material functions ; rheological constitutive equation ; fractional derivative
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Starting from an analysis of the rheological behavior of the complex modulus predicted by the Cole-Cole formalism, a generalized Cole-Cole ansatz is suggested in order to overcome the related difficulties. The corresponding rheological constitutive equation with fractional derivatives belonging to the generalized Cole-Cole respondance is stated and the characteristic material functions of the linear viscoelasticity theory (like the dynamic modulus and compliance, the relaxation and ratardation functions, the spectra, etc.) are derived. Model predictions of these functions will be compared with experimental results from dynamical measurements and creep data on different polymer systems which show cooperative phenomena (polymeric glasses and gelling systems). One can see that the modified ansatz fits the data very well, in spite of its relative simplicity.
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    A constitutive equation for a non-Newtonian liquid (1992)
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    Rheologica acta 31 (1992), S. 3-13 
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    Keywords: Liquid ; non-Newtonian liquid ; constitutive equation ; principal stretches
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The K-BKZ constitutive equation for non-Newtonian liquids usually uses as invariants the coefficients of the characteristic equation of a certain finite strain tensor. We show that the use of the roots of this equation, the squares of the principal stretches, is more efficient. We use a product of the linear relaxation spectrum and a simple sum of powers of the principal stretches as the “energy function” in the K-BKZ theory. The predictions of this theory agree with Meissner's data to a good approximation over many decades.
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    The recoil of rigid PVC (1992)
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    Rheologica acta 31 (1992), S. 44-54 
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    ISSN: 1435-1528
    Keywords: Rigid polyvinyl chloride (PVC) ; constitutive equations ; recoil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Polyvinyl chloride (PVC) is widely used in industry, but it is difficult to find any extensive discussion of theological relations that describe it. The present paper discusses the behaviour of rigid PVC in extensional deformations at various temperatures. In the tests, a step elongation was applied at an initial time, then after a delay the specimen was cut, permitting recoil. Both linear and nonlinear strain regimes were studied; the linear relaxation properties (relaxation function, storage modulus) were cross-checked with eccentric-disk measurements. In the non-linear strain regime a single-integral constitutive equation of the KBKZ Wagner type was used. Separability of time and strain effects was demonstrated in our tests and so a “damping function” could be found which was only a function of strain. Video recordings of recoil were made, and detailed predictions of the strain-time behaviour were checked against experiments. Various constitutive equation proposals were used in the comparison, and the separated kernel integral irreversible model performed reasonably well; some other models of a differential type, and a Doi-Edwards model were not as accurate.
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    Dynamics and rheology of a dilute suspension of dipolar nonspherical particles in an external field: Part 1. Steady shear flows (1992)
    Springer
    Rheologica acta 31 (1992), S. 94-117 
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    ISSN: 1435-1528
    Keywords: Suspension theology ; spheroid ; Brownian diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Suspensions of small nonspherical particles having dipolar moments exhibit non-Newtonian behavior under the influence of shear and external fields. Numerical methods are presented for calculating the rheological and rheo-optical properties of dilute suspensions of Brownian particles having permanent dipoles subject to time-dependent shear and external fields. The numerical methods employ the Galerkin method of weighted residuals to solve the differential equation for the particle orientation distribution function. The steady-state shear flow intrinsic viscosity of suspensions of particles with sufficiently extreme aspect ratio is predicted to exhibit a maximum value attained for intermediate shear rates at selected field orientations. These numerical results provide valuable insight into the coupling which occurs between the effects of rotary Brownian motion, the hydrodynamic resistance of nonspherical particles, and the external torque exerted on dipolar particles. The results are applicable to both suspensions of magnetic particles and electrically dipolar particles.
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    In situ technique for monitoring the gelation of UV curable polymers (1992)
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    Rheologica acta 31 (1992), S. 151-160 
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    ISSN: 1435-1528
    Keywords: Radiation cross-link ; ultraviolet radiation ; gelation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Ultraviolet-radiation-cured cross-linked systems are used extensively in optoelectronic applications. We describe a new in situ technique for doing controlled curing of photosensitive materials and monitoring the gelation through dynamic theological measurements. In this method, a sample placed between quartz windows of a modified parallel plate fixture of a Rheometrics Mechanical Spectrometer is radiated from a collimated UV source using a liquid light guide and a mirror. By varying the sample exposure to UV radiation, the degree of cross-linking can be precisely controlled to observe the material behavior in the pre, post, and critical gel state. Time-dependent measurements on urethane based materials show the gelation behavior to have an “induction” period with no change in dynamic moduli (G′, G″), followed by their sharp increase as the materials develop a network structure. The critical gel point is characterized by a power-law dependence of the dynamic moduli on frequency. The gelation kinetics scales with sample thickness and radiation intensity, the scaling factor in both cases being the critical gelation time. The rheological measurements correlate with differential photocalorimetric studies.
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    Purely elastic interfacial instabilities in superposed flow of polymeric fluids (1992)
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    Rheologica acta 31 (1992), S. 413-420 
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    ISSN: 1435-1528
    Keywords: Interfacial stability ; viscoelastic fluids ; plane Poiseuille flow ; multiphase flow ; elastic instability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Purely elastic interfacial stability of superposed plane Poiseuille flow of polymeric liquids has been investigated utilizing both asymptotic and numerical techniques. It is shown that these instabilities are caused by an unfavorable jump in the first normal stress difference across the fluid interface. To determine the significance of these instabilities in finite experimental geometries, a comparison between the maximum growth rates of purely elastic instabilities with instabilities driven primarily by a viscosity or a combined viscosity and elasticity difference is made. Based on this comparison, it is shown that purely elastic interfacial instabilities can play a major role in superposed flow of polymeric liquids in finite experimental geometries.
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    URL: http://dx.doi.org/10.1007/BF00701121
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    Measurement of the dynamic viscoelastic properties of polymer solutions using the Birnboim-Schrag multiple lump resonator. A theoretical and numerical study (1992)
    Springer
    Rheologica acta 31 (1992), S. 440-458 
    Details
    ISSN: 1435-1528
    Keywords: Dynamicviscoelasticity ; polymersolution ; multiple lumpresonator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The Birnboim-Schrag multiple lumped resonator (MLR) is the most sensitive and precise instrument in existence for dynamic viscoelastic measurements on dilute low-viscosity polymer solutions in the frequency range 100–8000 Hz. Estimation of polymer viscoelastic spectra from MLR-data has so far been carried out using an approximate dumbbell theory for description of the torsional dynamics of the resonator itself. Here, we report on the development of a significantly improved mathematical description of the resonator dynamics in the absence and presence of surrounding polymer solution. For some of the lumps the relative torsional displacements predicted by dumbbell theory and the new analysis differ by as much as a factor of 2. In an accompanying paper, we show that the predictions of our new theoretical analysis is in excellent agreement with experimental measurements of resonator dynamics. The new analysis does not rest on any particular choice of number of lumps, relative lump size, which lumps are surrounded by polymer solution, or the length or the diameter of each torsional spring. The mathematical analysis takes fully into account the mass and the energy loss of each torsional spring as well as the mechanical coupling between each spring and the surrounding medium. This part of the analysis is carried out in terms of damped torsional waves. An analytical analysis in terms of normal modes as well as the results of numerical analysis of the full set of simultaneous differential equations describing the resonator torsional dynamics are presented. The relationship between idealized dumbbell theory and normal mode theory is discussed. We also demonstrate how more accurate estimates of the viscoelastic parameters for polymers from experimental data can be obtained using the improved theory.
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    URL: http://dx.doi.org/10.1007/BF00701124
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    An automated dynamic viscometer with air bearing and inductive transducers for angular displacement detection (1992)
    Springer
    Rheologica acta 31 (1992), S. 471-480 
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    ISSN: 1435-1528
    Keywords: Complexviscosity ; dynamicviscometer ; rheometer ; triblockcopolymer ; transducer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A dynamic viscometer is described, with which the dynamic moduli in the frequency range from 2 × 10−3 to 10 Hz can be determined for liquids with 10−3 Pa〈 |G * | 〈102 Pa. Due to the application of an air bearing and inductive transducers for the detection of the angular displacement of both the drive and the measuring cylinder a sensitive apparatus has been made. Very small strains (γ0 ≅ 10−3) can be applied and only a small amount of sample (4 ml) is needed. The operation of the apparatus is fully computer-controlled, thus, long runs at various frequencies and temperatures are possible without operator intervention. The theoretical background, calibration procedure, and operation window are described. A presentation of some measurements on two polyisoprene/polystyrene triblock copolymer solutions concludes the work.
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    An analytical solution for the temperature profiles during injection molding, including dissipation effects (1992)
    Springer
    Rheologica acta 31 (1992), S. 592-602 
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    ISSN: 1435-1528
    Keywords: Injection molding ; viscous dissipation ; solidified layer ; diffusion equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract An analytical solution is obtained for the stationary temperature profile in a polymeric melt flowing into a cold cavity, which also takes into account viscous heating effects. The solution is valid for the injection stage of the molding process. Although the analytical solution is only possible after making several (at first sight) rather stringent assumptions, the calculated temperature field turns out to give a fair agreement with a numerical, more realistic approach. Approximate functions were derived for both the dissipation-independent and the dissipation-dependent parts which greatly facilitate the temperature calculations. In particular, a closed-form expression is derived for the position where the maximum temperature occurs and for the thickness of the solidified layer. The expression for the temperature field is a special case of the solution of the diffusion equation with variable coefficients and a source term.
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    X-ray diffraction study of anisotropy by formation and decomposition of nickel hydride Part I: Orientation dependence of the extent of phase transformation of nickel into nickel hydride (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 262-267 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The effect of microstructure and crystal direction on the extent of phase transformation (EPT) of Ni into β-NiH by cathodic charging with H has been investigated by X-ray diffraction. A measure for EPT in each crystal direction is the relevant volume fraction of β-NiH. EPT is controlled by the crystal direction in the case of heat-treated specimens. In the case of electrodeposited specimens, the imperfections of which are commensurate with those of cold-worked metals, EPT is controlled by both the crystal direction and the “dislocation-induced” anisotropy at the same time. The study provides new information on the characteristics of the phase transformation of bulk nickel into β-NiH.
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    Cyclic voltammetric investigation of the formation of intermetallic phases at a LiAl electrode in methyl acetate (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 255-261 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The formation of various Li/Al intermetallic phases at the LiAl electrode in methyl acetate was studied using cyclic voltammetry. The thickness of the α phase formed initially was estimated using the deposition and stripping method to be 1.1 nm. Repetitive cycling at the α or β phase potential led to a drastic increase in current over the first ten cycles before reaching a steady state. The formation of the β phase depended critically on the deposition potential and its presence at the electrode surface led to enhanced current in the reverse sweep, increased acceptance of deposited lithium, roughening and development of the area of the electrode upon cycling. The above effects were attributed to the difference in the lattice structure of the β phase as compared to the α phase, which greatly affected the electrode kinetics upon phase transition. The deposition of the more reactive LiAl alloys at more cathodic potential, namely −3.80 V, led to the formation of a passivating film which was broken down at more cathodic potential when the electrode surface had undergone vigorous chemical reaction with the solvent. Methyl acetoacetate was identified using i.r., n.m.r., u.v. and electrochemical techniques to be the major reaction product and a possible reaction mechanism was proposed.
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    Slow strain rate and constant load tests of A 285 and A 516 steels in Bayer solutions (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 396-403 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Stress corrosion cracking (SCC) experiments were carried out on A 285 and A 516 steels by slow strain rate and constant load techniques. The influence of the impurities contained in Bayer solution on the susceptibility to SCC was studied. The results obtained by both techniques indicated that aluminate ions promote passivation but the oxide layer includes numerous defects and the SCC susceptibility increases. The slow strain rate experiments provided a rapid method for investigating caustic stress corrosion cracking and intensified the susceptibility to SCC compared to the results obtained by the constant load technique. In the passive potential region, some shallow cracks were detected only when the experiments were conducted at slow strain rate in solutions containing aluminate ions. The presence of such cracks indicated that anodic protection could not entirely prevent SCC in the Bayer solution.
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    Book reviews (1992)
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    Journal of applied electrochemistry 22 (1992), S. 408-408 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
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    URL: http://dx.doi.org/10.1007/BF01092697
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    Studies of platinum electroplating baths Part I: The chemistry of a platinum tetrammine bath (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 415-420 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The chemistry of a new commercial electroplating bath for platinum, based on a Pt(NH3) 4 2+ salt in a phosphate buffer, is investigated using195Pt NMR and microelectrode techniques. It is shown that the maximum rate of deposition is determined by a homogeneous chemical reaction preceding the electron transfer step; the nature of this homogeneous chemical reaction is discussed.
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    Microcalorimetric study of the self-discharge of the NiOOH/Ni(OH)2 electrode in a hydrogen environment (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 409-414 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A microcalorimetric method has been used to investigate the self-discharge behaviour of nickel oxyhydroxide electrodes in a pressurized gaseous hydrogen environment. It was found that the heat generation rate is proportional to hydrogen pressure, and is significantly dependent on the immersion state of the electrode in the electrolyte. Hence, diffusion of dissolved hydrogen gas towards or within the electrode controls, at least partially, the self-discharge rate. However, the heat generation decreases exponentially with time, indicating that self-discharge is also proportional to the amount of the charged active material available for the reaction. The presence of Mg, Co and Cd oxides or hydroxides appears to inhibit self-discharge. It was found that direct chemical reaction between dissolved hydrogen and the active material dominates, while in addition, electrochemical oxidation of hydrogen coupled with electrochemical reduction of the active material might also occur at a much smaller rate than the direct reaction.
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    Studies of palladium electrodeposition from baths based on Pd(NH3)2X2 Part II: X=Br and X=NO2 (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 421-424 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The chemistry and electrochemistry of electroplating baths based on Pd(NH3)2Br2 and Pd(NH3)2(NO2)2 has been investigated and compared with that previously reported for Pd(NH3)2Cl2. It is shown that electroactive species in all the baths is Pd(NH3) 4 2+ and, hence, the mechanisms and current efficiencies for the cathodic deposition of palladium metal are similar in all three media. On the other hand, only in bromide electrolytes is the palladium found to dissolve anodically.
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    Electrochemical intercalation of sulphuric acid into CrO3-graphite intercalation compounds in aqueous solution (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 535-540 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The electrochemical process of intercalation-deintercalation of sulphuric acid into chromium trioxidegraphite intercalation compounds (CrO3-GICs) has been studied using 12 M H2SO4. It is shown that the anodic oxidation reactions of CrO3-GICs and cathodic reduction of the product of anodization are different when compared to those occurring in the pure graphite. The differences in the slow cyclic potentiodynamic curves, depending on the method of preparation of CrO3-GICs, are considered. The practical implications of the electrochemical transformation of CrO3-GIC for battery applications are shown.
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    Synthesis and properties of polyaniline obtained using sulphamic acid (1992)
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    Journal of applied electrochemistry 22 (1992), S. 563-570 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The results of investigations of the chemical and electrochemical polymerization of aniline in sulphamic acid medium and its characterization by electrochemical and spectroscopic techniques are presented. The investigations reveal that sulphamic acid medium affects, not only the polymerization process, but also its electrochemical characteristics.
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    Effect of a polyethoxylate surfactant on the electrodeposition of tin (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 558-562 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The electrodeposition of tin in the presence of polyethoxylated additive TX-102 has been investigated in acid medium. The additive causes a substantial increase in the overpotential for the discharge of Sn2+ ions. Below 0.12 g dm−3 the additive has little effect on the quality of the tin deposits. Periodic oscillations in the voltage of the cell are observed, which are associated with the initial growth of whiskers. For higher concentrations of additive, the deposits are smooth and homogeneous, and no growth of whiskers and no voltage oscillations are observed. The effect of TX-102 for concentrations below the CMC has been interpreted in terms of blockage of high energy sites of preferential growth on the tin surface. For additive concentrations above the CMC, micelles are formed. These high molecular weight aggregates also block the surface, hindering the mass transport of Sn2+ through a membrane-like layer that forms on the tin.
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    Determination of arsenic(III) in caustic melts (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 581-584 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Voltammetric and potentiometric methods were evaluated for the determination of As(III) levels in molten sodium hydroxide at 450°C. Because of the crystallization of As(V) salts on the working electrode, voltammetric measurements were limited to less than 3 wt% As(III) in melts containing up to 6 wt% total arsenic and only 2 wt% in melts containing up to 12 wt% total arsenic. Potentiometry has maximum sensitivity when the As(III)/As(V) ratio was near 1: 1 at 12 wt% total arsenic. The applicability of the two methods for control of an As(III) to As(V) oxidation process was evaluated.
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    Study of the electrochemical reduction of lead chloride on a liquid lead electrode in NaCl-KCl melt (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 577-580 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The electrochemical reduction of lead chloride on a liquid lead electrode of renewable surface was investigated in the NaCl−KCl eutectic melt at 700°C. Current oscillations were shown by voltammetric study. Under these circumstances the analysis of the experimental data was equivocal. Chronopotentiometric techniques similarly revealed potential perturbations. Nevertheless, it was possible to show that the lead chloride reduction occured in one reversible step involving a two electron transfer, according to the reaction $$PbCl_2 + 2e^ - \Leftrightarrow Pb + 2Cl^ - $$ The observed perturbations were ascribed to the electrode movements. Impedance measurements corroborated the results obtained by other methods: the electron transfer is fast and the electroactive species diffusion is the limiting step. The liquid electrode was considered similar to a rotating electrode whose Levich convective diffusion layer thickness and rotation speed were estimated.
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    News items (1992)
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    Journal of applied electrochemistry 22 (1992), S. 592-592 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
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    Effect of gas sparging on mass transfer in zinc electrolytes (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 596-605 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The effect of sparging on mass transfer is reported for zinc electrolytes containing antimony and antimony-free electrolytes. Comparative results with non-sparged electrolytes show, an enhancement in mass transfer. In the sparged electrolyte, the mass transfer coefficients,K Zn, increase with increasing current density, antimony additions, and sulphuric acid concentration. The deposition morphology is consistent with the mass transfer results. A relationship between the mass transfer coefficients for sparged and non-sparged systems is obtained. The relationship correlates satisfactorily with the data and provides a quantitative method for determining the degree of enhancement in mass transfer coefficients due to sparging. The correlation which best represents the mass transfer data for sparged zinc electrolytes is $$Sh = 105(ReSc)^{0.23} $$ whereSh, Re, andSc are the Sherwood, Reynolds, and Schmidt numbers, respectively. The correlation represents the case where sparging is applied to a gas evolving electrode, hydrogen in this case.
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    The degradation of aluminium cathodes by fluoride ion during zinc electrowinning (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 606-612 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The influence of fluoride ions on aluminium cathode surface degradation during zinc electrowinning has been studied. Electrolyte with a composition similar to that employed in plant operations has been used. A direct correlation is shown between the electrolyte fluoride content and the number of deposition cycles possible before zinc removal becomes difficult. The role of initial nucleation and starting electrode morphology is discussed in terms of the degree of adherence observed. Electrochemical tests have also been made on the electrodes at various stages of the process in an attempt to gain a better fundamental understanding of the mechanisms responsible for the adherence. The results indicate that the severity, of the adherence is generally determined by the amount of residual zinc remaining on the surface after stripping and the fluoride content of the solution during plating. The contribution of physical surface condition alone seems to be less significant than the chemical conditions imposed during deposition.
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    Quantum mechanical calculations of amino pyrazole derivatives as corrosion inhibitors for zinc, copper and α-brass in acid chloride solution (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 644-648 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Quantum mechanical calculations have been applied to a series of pyrazole derivatives used as corrosion inhibitors for zinc, copper and α-brass in order to assess quantum chemistry as a means of evaluating effectiveness of corrosion inhibitors. The corresponding structures have been optimized and the energies and coefficients of their molecular orbitals (HOMO and LUMO) have been computed using the semi-empirical method, MNDO. The theoretical results are then compared with experimental data.
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    Effect of organic acids and bases on cathodic corrosion of aluminium in chloride solutions (1992)
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    Journal of applied electrochemistry 22 (1992), S. 649-656 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract An attempt was made to inhibit cathodic corrosion of aluminium by the use of organic acids and bases. The corrosion is assumed to be caused by the effect of OH− ions formed from water upon cathodic hydrogen evolution. This is known to result in hydration of the protective oxide film and chemical attack on the metal. Hence, organic substances were expected to inhibit the corrosion by consuming OH− ions as well as by an adsorptive effect. The substances tested were HAc, HPro, HBut, HNic, TEA, Pyr, 3-Pic, 4-Pic, 3,5 Lut, 2,6 Lut, 2,4,6 Col, 4- HP, 2,4 AMP, 6,2 AMP, 2 AP and 3 AP. The best effect was achieved by TEA, 2,4 AMP and 2 AP, the potential window for low corrosion rate being extended by several hundred millivolts.
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    Scale-up studies of an Fe/Cr redox flow battery based on shunt current analysis (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 668-674 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Scale-up studies of a 0.7 kW single stack redox flow battery to a 2.1 kW three-stack assembly based on shunt current analysis are presented. The influence of the shunt-dependant design parameters on the energy efficiency of the system has been analysed for a single stack battery. Scale-up studies have been carried out in order to achieve energy efficiency in the three-stack assembly similar to that obtained for the single-stack system. The influence of the length of the hydraulic interconnection of the stacks and the assembly current on energy efficiency has been analysed. A shunt current calculation model for a three-stack assembly has been developed.
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    Comments on the estimation of caustic current efficiency of ion exchange membrane chlor-alkali cells (1992)
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    Journal of applied electrochemistry 22 (1992), S. 675-677 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
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    Activation studies on titanium anodes used in MnO2 electrodeposition (1992)
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    Journal of applied electrochemistry 22 (1992), S. 722-727 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Titanium anodes from the electrolysis of electrolytic manganese dioxide (EMD) were activated chemically and electrochemically. The surfaces of activated and nonactivated titanium were characterized. Unlike nonactivated titanium, activated titanium evolved hydrogen and displayed a steady open circuit voltage. Hydrides precipitated on both activated and nonactivated surfaces. The passivating film grown on the anode during EMD deposition thinned during partial cathodic reduction and changed in composition from TiO2 to TiO x . Titanium anodes precoated with a thin layer of MnO2 showed a delay in cathodic activation proportionally to the thickness of the precoat. A considerable difference in hydrogen diffusivity through thin and thick precoats is inferred from the time delay to activate the titanium surface.
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    Electrochemical investigation of the diffusion of lithium in β-LiAl alloy at room temperature (1992)
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    Journal of applied electrochemistry 22 (1992), S. 728-732 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The chemical diffusion coefficients of lithium in β-LiAl alloy were measured by the use of transient techniques such as chronopotentiometry, chronoamperometry and a.c. impedance spectroscopy in 1 M LiClO4-propylene carbonate at 25° C. A β-LiAl layer, formed by electrodepositing lithium on a thin aluminium substrate having a microstructure of preferred (100) orientation, was mainly used. The values of the diffusion coefficients were found to be of the order of 10−10 cm2s−1, which are close to those reported in the literature. A scatter in the coefficient was discussed in terms of the formation and disruption of the passivating layer on the alloy.
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    Indirect anodic oxidation of anthracene to anthraquinone in a slurry electrolyte system in the presence of both surfactant and redox mediator (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 743-748 
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    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The anodic oxidation of anthracene has been studied in a slurry electrolyte containing both the redox mediator, Mn3+/Mn2+, and surfactant, dodecyl-benzene-sulphonate (DBS). The reaction mechanism, kinetics and the factors which affect the current efficiency of anthraquinone production were explored. Both the experimental results and the theoretical analysis show that the reaction is second order, i.e. first order with respect to Mn3+ and DBS, when the concentration of DBS is less than 1.64×10−4M and is first order with respect to Mn3+ only when the DBS concentration is larger than 1.64×10−4M. No anthraquinone was found in the absence of DBS. The main factors affecting the current efficiency of the anodic oxidation of anthracene to anthraquinone in the presence of both Mn3+/Mn2+ and DBS are H2SO4 concentration, current density, anthracene particle size, concentration of DBS and redox mediator as well as temperature. The current efficiency is slightly affected by the concentration of DBS and agitation rate when the concentration of DBS and agitation rate are higher than 1.64×10−4M and 700 r.p.m., respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01027504
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    Electronic Resource
    Electron conducting organic coating of mild steel by electropolymerization (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 756-764 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The aim was to coat mild steel with an electron conducting polymer in order to replace any possible electrochemical corrosion of the metal by another electrochemical reaction occurring on top of the film. In view of potential industrialization, electropolymerization of a water soluble monomer was studied. In most cases, this was achieved by oxidation, and the substrate had to be passivated. Polyaniline, was obtained in nitric acid solution. Films had a good structure but were brittle and powdery on the surface. Except on tin free steel, they were insulating. Polypyrrole was a better candidate. Prepared from a Na2SO4 solution, films were conductive, ensured good corrosion resistance of the substrate but they were brittle and adhesion to the substrate was not high. Furance, thiophene and iron substituted vinylpyridine complex were tried without success. Further, research should consider copolymerization of pyrrole with other monomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01027506
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