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  • Articles  (58)
  • Physics  (58)
  • Wiley-Blackwell  (58)
  • International Union of Crystallography
  • 1985-1989  (58)
  • 1940-1944
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 1997-2003 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of butadiene by lithium-based initiators in aliphatic hydrocarbon solvents in the presence of dipiperidinoethane gives a highly 1,2 structure. This system was studied to determine the factors that govern the structure. The effect of this complexing agent on the kinetics of propagation, the microstructure of the polymer, and the ultraviolet spectrum of the active chain end was measured. The results suggest that more than one solvated species form, all giving highly 1,2 polymer structures, but that a solvate containing one chain end with one dipiperidinoethane molecule is the principal reacting species which gives close to 100% 1,2 structure. This reacting center has a high proportion of trans-structure in the allyllic ion, únlike most complexed active chain ends, which are often highly cis. It is this transstructure in the ion that is thought to be responsible for the polymer structure.
    Additional Material: 5 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 387-404 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The self-diffusion coefficient D of paraffin and polyethylene melts - covering the range between N = 19 and 103 where N is the number of monomeric units - was measured by the pulsed-magnetic-field-gradient NMR method for diffusion times between 3 ms and 1 s. For the paraffins, D is proportional to N-2 though the molecular weights are smaller than the critical molecular weight for entanglement. In polyethylene, melts a strong dependence of the diffusion coefficient on the diffusion time is observed, whereas no such dependence is found in paraffin melts. A mathematical formalism for describing spin-echo attenuation in terms of a velocity autocorrelation function is shown to yield qualitative agreement with the experimental results.
    Additional Material: 8 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1869-1881 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Far-infrared spectra of a series of un-neutralized and neutralized lightly sulfonated polystyrenes with varying sulfonation levels have been investigated to seek spectroscopic evidence for microphase separation known to control the physical properties of these polymers. Broad, strong absorbance bands, not found in the spectrum of unmodified polystyrene, are observed in the spectra of the sulfonated analogs. The effects on the far-infrared spectra both of sulfonation level and of the mass and charge of the neutralizing cation are discussed in terms of cation motion and the formation of ion-rich domains.
    Additional Material: 7 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 2931-2945 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thin films of cured MY720/DDS epoxy resins were treated with blocking reagents for hydroxyl, amine, and epoxide functional groups. Infrared spectroscopy (IR) and differential scanning calorimetry (DSC) were used to monitor the progress of the reaction. Treated films were soaked in distilled water at 30°C for 720 h, and the corresponding moisture absorption determined gravimetrically. Samples treated with N-methyl-N-t-butyldimethylsilyl trifluroacetamide (MTBSTFA) containing 1% t-butyldimethylchlorosilane (TBDMCS) in dimethylsulfoxide (DMSO) at 30°C showed a maximum reduction in the IR peak at 3400 cm-1 (OH and NH) of 39% and a 100% reduction in the epoxide peak at 904 cm, -1. The moisture absorption was 1.9%, a reduction of 58% compared to the untreated films (ca. 4.5%). The reactions show dependencies on time and temperature and are diffusion controlled. Samples treated with trimethylsilyl isocyanate (TMSI) in DMSO a 70°C showed 72% reduction in the 3400 cm-1 IR peak; DSC thermograms do not show an exothermic energy, suggesting that all epoxide groups reacted. These reactions are primarily dependent on time and temperature. The moisture absorption of TMSI treated samples was 1.0% (75% reduction). Samples were also treated with m-trifluoromethyl phenyliscyanate (MTFPI). The reduction in the IR peak at 3400 cm-1 was 9%, but the moisture absorption was 2.4% - a reduction of 47%.
    Additional Material: 12 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 569-573 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 1771-1785 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements of saturated liquid densities and ethylene solubilities in ethylene - polyethylene systems up to 26.1 MPa and 493.1 K were obtained using a new variable-volume static cell after a careful investigation of the influence of inhibitors of polymerization of ethylene under experimental conditions.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 2177-2195 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyamides were synthesized at -60°, -40°, -20°, and 0°C from sebacyl bisketene and 1,6-hexamethylenediamine in either acetone or methylene chloride. At the lower reaction temperatures oligomers predominated in solution but at 0°C the product was crosslinked. The polyamides were subjected to m-cresol extraction at elevated temperatures for up to 14 days. The m-cresol soluble and insoluble fractions were characterized by weight, infrared spectroscopy, dilute solution viscosity, and gel permeation chromatography. Infrared analysis of the soluble and insoluble portions showed the degree of branching of the polyamide, identified the branching point at the secondary amide proton position, and gave an indication of the degree of branching required before insoluble products resulted. Dilute solution viscosity and gel permeation chromatography were used to demonstrate the existence of low molecular weight (Mw) oligomer species in the soluble portion. Differential scanning calorimetry experiments revealed that polyamides synthesized below their glass transition temperature would not crystallize which resulted in abnormal thermal characteristics. Annealing at elevated temperatures allowed crystallization to occur and the expected thermal character to develop.
    Additional Material: 14 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 411-427 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser-initiated polymerization of cyclohexene oxide in the presence of maleic anhydride was investigated. The influences of solvents laser irradiation time and the monomer feed ratio on the polymer yield and composition were evaluated. The rate of polymerization increased with an increase in the molar concentration of maleic anhydride in the monomer feed. Short irradiation times of 1-3 min duration gave very high yield of epoxy polymer (〉80% conversion). Infrared spectral studies of the polymer product indicated the formation of polyether linkage at lower levels of conversion and an adduct of polyether and maleic anhydride at higher polymer conversions. The quantitative chemical analyses results also showed similar results. The results indicated that the polymerization was initiated by the excited charge transfer complex between the electron donor, cyclohexane oxide, and the electron acceptor-maleic anhydride. In the initial stages of polymerization, cyclohexene oxide undergoes a cationic polymerization in the presence of the radical anion of maleic anhydride. Laser-initiated polymerization of cyclohexene oxide/maleic anhydride is several hundred times more efficient than UV-initiated polymerization, as measured by the energy absorbed by the polymer system.
    Additional Material: 7 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 535-548 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The emulsion copolymerization of styrene and sodium styrene sulfonate has been shown to be a feasible preparative route to ionomeric sulfonated polystyrene. The properties of these copolymers are reported elsewhere. The copolymerization rate was found to be dramatically enhanced when compared to that for the emulsion copolymerization of styrene under identical conditions. This copolymerization was studied in detail and two mechanisms were proposed to account for these rate differences. An increase in the number of polymerizing particles in the copolymerization with consequent rate enhancement was substantiated by electron microscopy. However, the data indicate that the rate differences cannot be fully accounted for by this effect. In addition, a gel effect is proposed as a second contributor to the enhanced rate. This gel effect is believed to result from the intermolecular association of the incorporated metal sulfonate units in the growing polymer particles. When a third monomer that plasticizes the ionic interactions is used the polymerization rate decreases. This supports the gel effect hypothesis.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 525-533 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sulfonated polystyrene (S-PS), which is of considerable scientific and technological interest, has been traditionally prepared by the sulfonation of preformed polystyrene. This report describes the preparation and properties of S-PS prepared by emulsion copolymerization of styrene and sodium styrene sulfonate. S-PS prepared by copolymerization gave solubility, solution behavior and thermal characteristics that are consistent with an ionomeric structure. The solubility characteristics indicated some chain-to-chain sulfonate heterogeneity. Thermal analysis studies indicated that the glass transition does not increase with increasing sulfonate content. This is contrary to what has been observed for S-PS prepared by sulfonation and suggests that the S-PS prepared by copolymerization is fundamentally different in structure than S-PS prepared by sulfonation of polystyrene.
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