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  • 1
    Digitale Medien
    Digitale Medien
    Size exclusion behavior of polymers in amide solvents (1996)
    Springer
    Polymer bulletin 36 (1996), S. 729-735 
    Details
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary The size exclusion chromatography of neutral polymers and polymers containing ionic groups was investigated using N,N-dimethylacetamide (DMA) as mobile phase. As reported previously for N,N-dimethylformamide (DMF), acrylonitrile polymers containing charges, even those at terminal end groups, showed markedly small retention volumes and multimodal peaks by refractive index and 280 nm UV detectors. In DMA containing small amounts of LiBr the peaks of the ionic polymers were shifted to small retention volumes while neutral polymers with analogous chemical structures did not show the same behavior. As in the case of DMF the peculiarities observed in DMA were attributed to the formation of supramolecular structures by the interaction of the ionic groups in the polymer and the ionic species from DMA decomposition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00338637
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  • 2
    Digitale Medien
    Digitale Medien
    Core Shell Silica-Silicon Hybrid Nanoparticles: Synthesis and Characterization (2004)
    s.l. ; Stafa-Zurich, Switzerland
    Journal of metastable and nanocrystalline materials Vol. 22 (Aug. 2004), p. 83-90 
    Details
    ISSN: 1422-6375
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Materialart: Digitale Medien
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/43/transtech_doi~10.4028%252Fwww.scientific.net%252FJMNM.22.83.pdf
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  • 3
    Digitale Medien
    Digitale Medien
    Copolymerization of Alkoxysilanes: An Interesting Route to Core-Shell Silica-Silicone Nanoparticles (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 570 (Feb. 2008), p. 24-32 
    Details
    ISSN: 1662-9752
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Notizen: Copolymerization of silicon alkoxides in alcoholic basic medium usingtrialkyl- or triarylchlorosilanes as terminator was investigated. Tetraethoxysilane(TEOS), phenyltriethoxysilane (PTEOS) and vinyltriethoxysilane (VTEOS) wereused as monomers and triphenylchlorosilane (TPCS) and trimethylchlorosilane(TMCS) as terminator. The copolymerization of TEOS with PTEOS and VTEOSproduces core-shell silica-silicone nanospherical hybrids containing large amounts offunctional groups in the structure of their external layer. The structure is the result ofthe fast hopolymerization of TEOS in a first stage of the reaction, forming the core,followed by copolymerization of TEOS and the alkyl- or vinyl-trialkoxysilanecomonomer in its last stage. The structure was confirmed by Raman and FTIRspectroscopy, wide angle X-ray scattering (WAXS) and thermogravimetry. Thecontrol of particle size is effectively made by the termination reaction and particleswith average diameter between 20 and 100 nm were obtained. Introduction of otherchemical functions on the surface of these nanoparticles can be carried out bycommon reactions with the functional surface groups. As an example, sulfonation ofparticles containing phenyl groups on the surface by direct sulfuric acid andchlorosulfonic acid was investigated and the results discussed
    Materialart: Digitale Medien
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/18/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.570.24.pdf
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  • 4
    Digitale Medien
    Digitale Medien
    Photosensitivity of modified natural polyisoprenes as function of the alipathic side chain (1991)
    Springer
    Polymer bulletin 25 (1991), S. 217-223 
    Details
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Modified natural rubber products were prepared by reaction with maleic anhydride followed by ring opening and condensation with different oxyalkylcinnamate esters. The values of Tg obtained for these photocrosslinkable polymers showed a complex relation to the number of C atoms of the aliphatic moiety. The kinetics of the dimerization reaction for thin films was followed by UV spectrometry. The film thickness plays an important role on conversion up to a threshold value, characteristic of each product. The expected relation between Tg and kobs was observed for products when Tg values were markedly different.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00310795
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  • 5
    Digitale Medien
    Digitale Medien
    Size exclusion behavior of polymers in amide solvents (1995)
    Springer
    Polymer bulletin 34 (1995), S. 585-592 
    Details
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary The abnormal behavior of acrylonitrile polymers shown by size exclusion chromatography (SEC) in N,N-dimethylformamide (DMF) was investigated by using model polymers having variable degrees of sulfonated moieties as electric charged groups. The unexpected small retention volume and very high UV absorption at 280 nm were observed in the case of the samples with ionic sulfonate groups even in very small amounts, as chain ends. The abnormal behavior was confirmed to be due to impurities of DMF decomposition which interact with charged groups in the polymers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00423355
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  • 6
    Digitale Medien
    Digitale Medien
    Application of photosensitive surfactant based on natural rubber in emulsion polymerizations (1996)
    Springer
    Polymer bulletin 36 (1996), S. 197-202 
    Details
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Photosensitive surfactant was prepared by incorporation of maleic anhydride to natural rubber, followed by introduction of cinnamate groups and neutralization of the remaining carboxylic groups. The surfactant was used in emulsion polymerization of styrene and acrylic monomers, giving rise to stable reactive emulsion. Coated onto HDPE, this emulsion lead to solid films which were submitted to UV irradiation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00294906
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  • 7
    Digitale Medien
    Digitale Medien
    Kinetic treatment for the photodimerization reaction of modified natural polyisoprenes (1991)
    Springer
    Polymer bulletin 26 (1991), S. 637-641 
    Details
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Natural polyisoprenes modified by the introduction of cinnamoyl groups have been obtained as films. In these polymers, aliphatic-(CH2)n- spacers of different lengths separate the main chain from the photosensitive group. Density measurements have been carried out, and the kinetic treatment of the photodimerization reaction is described. The relation between Tg and kobs to the size of the aliphatic spacer suggests that, at least for n=2 to 6, other factors may be affecting the reactivity of the cinnamoyl group.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00313218
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  • 8
    Digitale Medien
    Digitale Medien
    Photosensitive polyurethanes based on castor oil (1995)
    Springer
    Polymer bulletin 34 (1995), S. 663-668 
    Details
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Films of photosensitive polyurethanes based on castor oil and bearing increasing amounts of cinnamoyl groups were obtained and submitted to tensile tests and thermogravimetric analysis. The test samples were cut into strips, with the long axis making angles of 0, 30, 45, 60, 90, 120, 135, and 150° with the suspected direction of anisotropy. In another series of experiments, films were irradiated with a high pressure mercury lamp during different periods of time and again submitted to tensile tests.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00423366
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  • 9
    Digitale Medien
    Digitale Medien
    Size exclusion behavior of polymers in amide solvents (1995)
    Springer
    Polymer bulletin 34 (1995), S. 593-598 
    Details
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Size exclusion chromatography (SEC) procedure for the determination of molecular weight and molecular weight distribution of acrylonitrile polymers (PAN) is described. The Mark-Houwink-Sakurada parameters of PAN polymers in DMF and 0.01M LiBr-DMF at 60°C were estimated. The values of a parameters obtained by us for PAN prepared both by persulfate-metabisulfite aqueous system (PAN), and azo-bis-isobutyronitrile in DMF solution (PAN-A) were the same, while for PAN sample containing small amounts of sulfonated pendant groups (PAN-S) was higher. The addition of inorganic salt, such as LiBr, to DMF suppressed the abnormal SEC elution behavior observed in the solvent without the electrolyte although SEC of PAN-A showed almost the same results as in DMF with electrolyte. The universal calibration using monodisperse poly(ethylene oxide) standards as well as application of the Mark-Houwink-Sakurada parameters were satisfactory for the determination of the molecular weights.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00423356
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  • 10
    Digitale Medien
    Digitale Medien
    Kinetic behavior of UV-sensitive polymers from modified natural rubber (1993)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 4 (1993), S. 490-495 
    Details
    ISSN: 1042-7147
    Schlagwort(e): Cinnamoylated rubbers ; Photocrosslinking reactions ; Correlation of dimerization rate constants ; Glass transition temperatures ; Aliphatic spacers ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Photosensitive copolymers have been obtained by chemical modification of natural rubber. The introduction of the photoreactive cinnamoyl group in different conversions has been carried out by the reaction of natural polyisoprene with maleic anhydride, followed by ring opening and condensation with some oxyalkylcinnamate esters. These reactions gave rise to five polymer series. Each series, for which the anhydride content was kept constant, is constituted of five copolymeric products, differing from each other in the size of the aliphatic chain between the chromophore and the main chain. The photosensitive products were submitted to UV irradiation, and their kinetic behavior has been investigated in order to correlate structural dissimilarities with the dimerization rate constants.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pat.1993.220040802
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