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  • Polymer and Materials Science  (5)
  • Chemical Engineering  (3)
  • 1980-1984  (7)
  • 1965-1969  (1)
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  • 1
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The unexpected crystallinity of free radically polymerized poly(p-vinyltrifluoroacetophenone) (PVTFA) due to lateral order was previously found in this laboratory. To further the understanding of the relationship between chemical structure and crystalline order in polymers of the PVTFA type, polymers of similar structure were synthesized and characterized by differential scanning calorimetry (DSC). These polymers were poly(p-vinyldifluoroacetophenone) (PVDFA), poly(p-vinylphenylheptafluoropropyl ketone) (PVHFK), poly(p-vinylacetophenone) (PVA), and poly(p-vinylphenyltrifluoromethyl carbinol) (PVPTC). Only PVTFA had a crystalline melting temperature (188°C); 220-MHz nuclear magnetic resonance (NMR) measurements on the microstructure of PVTFA and PVDFA revealed broad peaks for the chain protons. The PVTFA was therefore assumed to be predominantly atactic. The results suggested that the unusual crystallinity of PVTFA was related to the unique size and interaction of the trifluoroacetyl moiety on the polymeric side chain.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Prior to the study of poly(o- and p-vinylbenzyl trifluoromethyl ketone) (PVTFK) polymers and their reaction with alcohols, the reactions of some simple model compounds with alcohols were investigated. The reaction of fluorinated ketones toward alcohols was determined by proton nuclear magnetic resonance (NMR) spectroscopy. Two fluorinated ketones-p-methylbenzyl trifluoromethyl ketone (p-MTFK) and o-methylbenzyl trifluoromethyl ketone (o-MTFK)-were prepared. Studies of the reaction of p-MTFK and o-MTFK to various alcohols based on NMR produced equilibrium constants (1M in CCl4) at 31°C that ranged from 0.1 to 6.0. The equilibrium constants for p-MTFK with alcohols were larger than those for o-MTFK. In addition, the equilibrium constants for primary alcohols were larger than those for secondary and tertiary alcohols. Steric effects in this reaction could explain the lowered equilibrium constants for o-MTFK and the secondary and tertiary alcohols.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copolymers of styrene/p-vinyltrifluoroacetophenone were prepared by two different reaction routes: (1) modification of polystyrene with trifluoroacetyl chloride and (2) copolymerization of styrene and p-vinyltrifluoroacetophenone (VTFA). There appears to be a limit to the modification method because only a maximum content of 14.5 mole % trifluoroacetyl functionality could be attached to the polymer before the onset of crosslinking. Differential scanning calorimetry (DSC) was used to determine their Tg's. In addition, the reactivity ratios of styrene and VTFA were investigated. The reactivity ratios and Q and e values were r1 = 0.30 ± 0.09 (styrene) and r2 = 1.3 ± 0.3 (VTFA); Q1 = 1.0 and e1 = -0.8 (styrene); Q2 = 0.44 and e2 = 1.93 (VTFA).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of new fluorinated ketone-containing polymers, poly(p-vinyltrifluoroacetophenone) (PVTFA), poly(p-vinyldifluoroacetophenone) (PVDFA), poly(p-vinylphenylheptafluoropropyl ketone) (PVHFK), and poly(o-and p-vinylbenzyltrifluoromethyl ketone) (PVTFK), were prepared by the free radical polymerization of the corresponding monomers. The monomers, p-vinyltrifluoroacetophenone (VTFA), p-vinyldifluoroacetophenone (VDFA), p-vinylphenylheptafluoropropyl ketone (VHFK), and o-and p-vinylbenzyltrifluoromethyl ketone (VTFK), were prepared by the reaction of Grignard reagent with the corresponding perfluoroacid or its lithium salt. Polymerization was a competitive side reaction during monomer preparation. Reduced side reaction and higher yields of monomer (based on the Grignard reagent) were obtained from the lithium salt of the perfluoroacid, compared with the perfluoroacid itself. These new substituted polystyrenes which contain fluorinated ketone functionality were characterized by their ability to (1) react with active hydrogen compounds such as alcohols or water; (2) have high glass transition temperatures and decreased solubility in nonpolar solvents (e. g., benzene) compared with polystyrene; and (3) be converted into other functional groups such as alcohols or acids by treatment with the appropriate chemical reagents. Beads of a styrene (ST) terpolymer with 2% divinylbenzene (DVB), which contained the CF3COCH2 function, were prepared by suspension polymerization of ST, VTFK, and DVB. The terpolymer, which contains 15-17% mole (or 0.70-0.71 meg/g) of CF3COCH2 swollen with a solvent, were shown to chemisorb alcohols.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 13 (1967), S. 739-744 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Normal freezing of several organic systems exhibiting simple eutectic behavior has been studied experimentally, and the occurrence of constitutional subcooling has been clearly established. This phenomenon, previously observed in systems of metallurgical interest, results in the instability of a planar solid-liquid interface and leads to solute trapping. This trapping mechanism quantitatively explains why eutectic forming systems exhibit solid phase concentration profiles identical to those expected of systems which form solid solutions. The onset of constitutional subcooling can be correlated and reliably predicted by theoretical equations.Although the process of normal freezing with no liquid phase agitation would appear to be well described by a diffusion model, free convection induced by concentration gradients renders a boundary-layer model more appropriate when the liquid density of the solvent exceeds that of the solute and freezing is in an upward direction.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 30 (1984), S. 765-769 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental study has been made for laminar mass transfer to a rotating disk and a rotating hemispherical electrode when sinusoidal alternating current (AC) together with direct current (DC) are flowing across the electrode/electrolyte interface. A resistor-capacitor circuit was used to measure the phase shift between the applied AC and the resulting periodical concentration overpotential. The limiting AC current density corresponding to a zero instantaneous surface concentration was determined as a function of AC frequency and DC current density. The experimental data agreed with the theoretical calculations in a regime of a dimensionless AC frequency K = (ω/Ω)Sc1/3 greater than 1 and less than 200.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A film model is presented for the analysis of mass transfer to a rotating hemispherical electrode when sinusoidal alternating current (AC) together with direct current (DC) are flowing across the electrode surface. The concentration of a diffusing ion is separated into two independent components: a constant DC component and a periodic AC component. The DC concentration is obtained by solving the steady-state convective mass transport equation with the perturbation method. The periodic AC concentration distribution is analyzed by the solution to the one-dimensional transient diffusion equation based on the concept of Nernst diffusion layer. The limiting AC current densities corresponding to a zero surface concentration of a reactive ion are investigated for various DC current densities and AC frequencies. The resulting periodic concentration overpotential wave and its phase shift with respect to the applied AC are examined. A comparison with a previous rigorous model indicates that the film model is a good approximation to the mass transfer calculation in the regimes of a dimensionless AC frequency K = (ω/Ω)Sc1/3 greater than 2 and less than 0.01.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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