Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Graft copolymerization of vinyl monomers in wool fibers (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 115-126 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Graft copolymerization of vinyl monomers, mainly methyl methacrylate, in reduced, successively alkylated, or KCN-Treated wool fibers was performed in the redox LiBr-persulfate system without homopolymer. The reduction gives a striking effect in promoting the graft copolymerization. Methylation or ethylene recrosslinking of the reduced wool, especially the former, decreases the graft-on remarkably. By the KCN treatment in which the conversion of disulfide to lanthionine bonds occurs, the grafting is decreased in the bromide-persulfate system but promoted in the system with persulfate alone. Methylation or KCN treatment of wool as well as reduction brings about a great increase in the absorption of persulfate. The grafting of the lanthionine-containing wool in the redox system accompanied by the liberation of bromine might be retarded by the pronounced bromination of monomers over the inhibiting of homopolymerization, because the lanthionine bonds are more stable to bromine than the disulfide bonds. In general, disulfide bonds and the other easily oxidized components of wool may perhaps play an important role in regulating the bromination of monomers and in the graft copolymerization without homopolymer. The molecular weight of graft polymer is decreased distinctly with increasing extent of reduction of wool. From these results, the thiol groups on wool are considered to give predominantly graft centers by the radicalotropy from SO4-·, OH·, and/or Br·.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1967.070110109
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    New method for graft polymerization of vinyl monomers in wool fibers (1965)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 9 (1965), S. 3465-3470 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: When a small amount of persulfate is dissolved in a relatively concentrated aqueous solution of bromide salts, especially LiBr, liberation of Br2 occurs to some extent. This system was utilized for the graft copolymerization of various acrylates in wool fibers using diethylene glycol monobutylether as monomer-solubilizer. The grafting was fairly well performed at a relatively low temperature (10-40°C.) and without homopolymerization while liberating Br2. This new graft copolymerization has been attributed to the concerted action of the fiber-swelling power of bromide salts, the following redox system, and the mild bromination of some monomers by which the grafting will proceed without homopolymerization. \documentclass{article}\pagestyle{empty}\begin{document}$ \begin{array}{*{20}c} {{\rm Br}^ - + {\rm S}_{\rm 2} {\rm O}_8^ - \to {\rm Br} \cdot + {\rm SO}_{\rm 4}^ - \cdot + {\rm SO}_{\rm 4}^ - } \\ {{\rm Br} \cdot + {\rm Br} \cdot \to {\rm Br}_{\rm 2} } \\ \end{array} $\end{document}
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1965.070091023
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Grafting onto wool. IV. Interaction of polymer radicals in the viscous media of wool fibers (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 3271-3281 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to study the termination reaction of polymer radicals in the viscous media of wool fibers, reduced, methylated, and S-carboxymethylated wool fibers were used for graft copolymerization of methyl methacrylate and styrene. With termination of poly(methyl methacrylate) radicals, two different termination reactions, recombination and disproportionation, were together involved in the grafting systems studied. The occurrences of two termination reactions in the system could be correlated with the mobility of the wool chain controlling the radical end mobility. With decreasing disulfide content in the fibers, disproportionation predominantly takes place among the mobilized chains. At a constant disulfide, the thiol content or the concentration of thiol anions becomes the determining factor for the termination reaction. A possible explanation for these phenomena in terms of the thiol and disulfide interchange reaction is presented. On the grafting of styrene, additional evidence was obtained that prevention and retardation of the interchange reactions followed mechanochemical bond scission of the disulfide and other covalent bonds and produced new free radicals which could initiate chain reactions.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170111219
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Grafting onto wool. V. Kinetics of graft copolymerization of methyl methacrylate in the viscous media of wool fibers (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 3283-3292 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The graft copolymerization of methyl methacrylate in S-carboxymethylated wool fibers was investigated in the aqueous LiBr-K2S2O8 system. The rate of grafting, the degree of polymerization of graft polymer, and the number of grafting sites were determined on varying the thiol content at a constant concentration of monomer. Kinetic considerations lead to the following expression in agreement with the experimental results: Z/DP = {(ktd + ktc)/kp2[M]2} Rp, where Z is the number of DNP endgroups of polymer; DP is the average degree of polymerization; kp, ktd, and ktc are the rate constants of propagation, termination by disproportionation, and termination by recombination, respectively; [M] is the concentration of monomer in fibers, and Rp is the overall rate of grafting. For wool fibers in media sufficiently high viscosity, the rate constants ktd and ktc of diffusion-controlled termination are approximately equal and not affected by the change in cross-link density, provided that the thiol and disulfide interchange occurs. The possibility of occurrence of mechanical bond scission through a radical mechanism is involved in systems with extremely small amounts of thiol groups.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170111220
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Crosslinking structure of keratin. I. Determination of the number of crosslinks in hair and wool keratins from mechanical properties of the swollen fiber (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 38 (1989), S. 1159-1172 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Hair and wool keratin fibers which had been treated with an 11 M LiBr solution containing N-ethyl maleimide showed typical rubberlike elasticity in a solution composed of equal volume of 8 M LiBr and diethylene glycol mono-n-butyl ether. Stress-strain curves and equilibrium force-temperature relations were measured for swollen hair and wool fibers. The non-Gaussian effects on deformation and the energy component in retractive forces were analyzed. On the basis of rubber elasticity theory, a method for estimation of the number of mechanically effective crosslinks in keratin fibers was proposed. A linear relationship between the crosslink density and the disulfide content was obtained from the data for a variety of keratin fibers (i.e., two different human hairs, horse hair, and 17 different wools). From the results of thermodynamical and non-Gaussian treatments for swollen keratin, it was suggested that the swollen fiber consists of a two-phase structure: a mechanically stable phase of higher crosslinked domains and rubbery phase with lower crosslink density. It was further found that considerable amounts of nondisulfide covalent crosslinks are present in wool and hair keratins.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070380613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Crosslinking structure of keratin: III. Rubberlike elasticity originating from non-uniform structures of the swollen hair and wool fibers (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1125-1131 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Hair and wool fibers treated with an 11 M LiBr solution containing N-ethylmaleimide showed typical rubberlike elasticity in a solution composed of equal volumes of 8 M LiBr and diethylene glycol monobutyl ether. Stress-strain relations of the swollen fibers were treated with a two-phase structural model: a mechanically stable phase of higher crosslinked domains and a rubbery phase with lower crosslink density. Stress-strain curves were analyzed by applying non-Gaussian chain statistics to the swollen keratin network, including microdomains, which act as reinforcing filler particles in rubber. Swollen hair showed about 2.3 times higher modulus than wool. It has been suggested that: (1) the difference in the modulus between the two keratins is attributable to the difference in the volume fraction of domains, and (2) the crosslink density of rubbery phase in hair is virtually identical to that in wool.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420426
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Grafting onto wool. III. Relationship between alpha- and beta-forms in wool keratin of grafted fibers (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 483-502 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A quantitative study of the change in the x-ray intensity diffracted from the α- and β-crystalline phases of grafted fibers was carried out. It was demonstrated that a part of the α-helical sections is disrupted by the deposition of polymer and that during extension processes a marked stabilization for the remainder results from the interaction between the residues on the α-helix and the rigid polymer chain. It was also considered that the disrupted sections are identical to the portions which would be easily deformed by stretching. The results on fibers containing hydrophilic polymer suggested little possibility that the β-chain crystal is produced from the disrupted chains of α-crystallites. The mechanism of the so-called α-β transformation was proposed as ⇌ α M, M* ⇌ β.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070170213
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Crosslinking structure of keratin. II. Intermolecular and intramolecular crosslinks in potassium-cyanide-treated wool fibers (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 38 (1989), S. 29-44 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The crosslinking structure of keratin fibers has been investigated. The reaction of wool with aqueous KCN was studied by means of chemical and physical methods. Quantitative conversion of disulfide (SS) groups of the cystine (Cys) residues into stable thioether (S) linkages was confirmed. In terms of mechanically effective and noneffective crosslinkages, the amounts of intermolecular and intramolecular crosslinks in the KCN-treated wools were determined from the analysis of the corresponding amino acids and mechanical experiment in which the shear modulus of swollen, rubberlike samples is determined from the relation between equilibrium stress and strain for simple extension of the fiber in a diluent. A modified elastic equation of state was used for the calculation of the number of intermolecular crosslinks. The front factor in the equation used was determined by combining the results obtained from purely chemical kinetics and the values of shear modulus of the swollen wools. The ratio of the number of intermolecular and intramolecular SS crosslinkages in the Lincoln wool, was found to be 64:36. The reactivity of the former is much higher than that of the latter, and these two types of SS crosslinks form substantially the same type of S crosslinks. The fraction of the Cys residues accessible to cyanideions depends mainly on the reaction temperature.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070380104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Amino acid end-group in commercial heparin. III. Determination of the number of amino groups of amino acid and hexosamine residues per heparin molecule (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 249-258 
    Details
    ISSN: 0887-624X
    Keywords: heparin ; 2,4,6-trinitrobenzenesulfonic acid ; kinetics ; α-amino acid ; hexosamine residue ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of heparin with 2,4,6-trinitrobenzenesulfonic acid (TNBS) were studied spectrometrically. Seven different commercial heparins were used in this study. The amino groups react with TNBS to form equimolar amounts of trinitrophenylated (TNP) amino groups and bisulfite ions. The TNP-amino groups further react with bisulfite ions to form the monosubstituted anionic sigma complex. The absorption spectrum with two maxima at approximately 350 nm and approximately 420 nm, characteristic of either the TNP-amino groups or the complex, was analyzed for the reaction of TNBS with heparin. It was shown that the reactivities of TNBS with amino groups from α-amino acid and hexosamine residues are greatly different. By combining the results of the reaction kinetics and the reaction of heparin with Sanger's reagent, the number of the α-amino groups and the free amino groups in hexosamine residues were determined. These data have been performed with a range of heparins from different commercial sources, of different activities and physical characteristics. No correlation was found between the free amino contents of these heparins and biological potency. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310129
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Amino acid end-group in commercial heparin. II. Reaction kinetics of the amino end groups with 2,4,6-trinitrobenzenesulfonic acid (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1497-1503 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three different commercial heparins were trinitophenylated with 2,4,6-trinitrobenzenesulfonic acid (TNBS) under aqueous conditions. The reaction kinetics of amino groups in heparin with TNBS showed that the reactivities of amino groups were significantly different for free amino groups on heparin, compared to reactivities in peptides and amino acid residues attached to heparin molecules. With TNBS, unreactive amino groups were always present during the reaction.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...