WILBERT

Wildauer Bücher+E-Medien Recherche-Tool

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
Filter
  • 1980-1984  (1,442)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 839-855 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymerization of isobutyl vinyl ether (IBVE) initiated by trifluoroacetic acid (TFA) in 1,2-dichloroethane and in 1,2-dichloroethane/carbon tetrachloride mixtures has been studied over the temperature range -2,5°C to 35°C. Provided that the ratio [IBVE]/[TFA] did not exceed 88 and that 2·10-4 mol·1-1 〈 [TFA] 〈 4·10-3 mol·1-1 polymerization was the only detectable reaction, and the initial rate of reaction R0 was equal to k[IBVE]2[TFA]. The activation energy of the rate = (34 ± 2) kJ · mol-1 and the activation energy of the molecular weight = - (11,9 ± 0,5) kJ · mol-1. When [TFA] 〈 1·10-4 mol/l, no reaction was detectable. The polymers produced had molecular weights less than 4400; the only transfer is by monomer and this is the main chain-breaking step. The reaction was unaffected by the addition of water for [H2O] 〈 [TFA]. The rate depended on the solvent dielectric constant, but in a manner suggestive of a dipole-dipole reaction. A mechanism is proposed for the reaction in which the reactive intermediates are trifluoroacetate esters solvated by monomer.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 857-867 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscoelastic properties of poly(α,α-diethyl-β-propiolactone) were investigated in the linear range using stress relaxation and dynamic mechanical methods. Using Ferry's reduction method, a horizontal shift factor was determined at each temperature, that satisfactorily agreed with the WLF equation in the transition zone. No vertical shift was required to superimpose different relaxation curves. The apparent activation energy was temperature dependent and passed through a maximum near Tg whose value is (311 ± 2)K. The relaxation spectrum has been calculated according to the first method of approximation of Schwarzl and Staverman. It consists of a high intensity plateau at shorter times, a wedge type portion with a slope of -0,15 and a low intensity plateau at longer times. Dynamical mechanical measurements revealed a β relaxation peak at 333 K and yielded the evidence of a γ peak around 120 K.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 869-890 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Branched copolymers of methyl methacrylate with ethylene dimethacrylate or pentaerythritol tetramethacrylate with high weight average molecular weights Mw were prepared by free radical polymerization. The double bond conversion of these polymers (β) was measured dilatometrically and the gel point (βc) was located by extrapolation of bulk viscosity measurements. The polymers were studied by light-scattering, 1H NMR and viscometry. Hence it was possible to investigate the relationship between the molecular weight Mw and the reduced conversion quantity (1 - β/βc)-1 and also the molecular weight dependence of the z-average mean square radius of gyration 〈S2〉z. Considerable deviations from the classical Stockmayer theory but also from percolation theory were observed. 1H NMR showed a relative small extent of ring formation (10 to 24%) and a reduced apparent reactivity of the pendant double bonds, while the delay in the gel formation appeared to be caused by a much higher ring formation (80 to 90%). This apparent inconsistency is explained by a size-dependent ring formation, where the extent of ring formation is increased with the molecular dimensions; simultaneously, the pendant double bonds become progressively less accessible to cross-linking by growing radicals. The molecular weight dependence of 〈S2〉z is found to be in agreement with this heterogeneous reaction model.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 891-901 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Among the methods to introduce functional groups in macromolecular compounds, the initiation of free radical polymerization by functional peroxyesters was investigated. m- and p-tert-butyldioxycarbonylbenzoic acids (3 and 8) were synthetized and their properties were studied. Differential scanning enthalpimetric study of the thermolysis kinetics of 3 and 8 led to the conclusion that these compounds are a little more stable than O,O-tert-butyl hydrogen monoperoxyphthalate (1). Thus, they could be applied under similar conditions. Solution and bulk polymerizations of styrene initiated by 3 or 8 were found to be efficient methods to obtain polystyrene substituted by carboxylic functions.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 903-911 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Modified polystyrenes were obtained by free radical polymerization of styrene using the macroinitiators α-tert-butyldioxyterephthaloyl(or phthaloyl)-ωtert-butyldioxyterephthaloyl(or phthaloyl)poly(oxyethylene) (3 and 4), which were synthetized. To examine the stability of such compounds, thermolysis kinetics of model compounds, OO-tert-butyl O-methyl monoperoxyphthalate (6) and terephthalate (7) were studied by differential scanning enthalpimetry. Suspension polymerization of styrene applying the industrial method, showed that the macroinitiator is able to initiate the process. A polystyrene containing up to 4% by weight oxyethylene units was obtained.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 545-555 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ammonium salt catalyzed copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride was studied. The conversion curves could be linearized by the first order equation and the experimental rate constants kexp for the initiation by various ammonium salts were determined. The rate of copolymerization was found to depend on the size of the cation but not on the type of anion. kexp is a function of the first power initiator concentration but is independent of epoxide and anhydride concentration. The activation energy for the cetyltrimethylammonium bromide (CAB) initiated copolymerization in nitrobenzene was determined to be 73,5 kJ/mol. The kinetic scheme of copolymerization, which agrees well with the experimental results, was solved. The rate constant of the copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride catalyzed by CAB in nitrobenzene was found to be 2,76·10-2l.mol-1·s-1. The ratio of rate constants for both propagation steps, i.e. reaction of carboxylate anion with epoxide (k3) and reaction of alkoxide anion with anhydride (k2), was determined to be k3/k2 = 0,2 ± 0,1.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 557-563 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2,6-Di-tert-butyl-4-vinylphenyl trimethylsilyl ether (1e) and 2,6-di-tert-butyl-4-vinylphenyl acetate (1c) were synthesized and polymerized by cationic and free radical initiators. The protecting groups could be splitted off from the polymers by hydrolysis in acidic medium or by reduction with lithium aluminium hydride, resp., yielding high molecular sterically hindered free polyphenols.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 565-573 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The decomposition reaction of hydrogen peroxide was carried out by using Fe(III)-3,4,3′,4′,3″,4″,3″′,4″′-octacarboxyphthalocyanine (Fe(III)-oaPc) as a catalyst, which has previously been reported by Boston et al. Fe(III)-oaPc is a remarkably effective catalyst for the reaction, compared with hemin, other metal-phthalocyanine compounds, or other iron complexes such as [Fe(III)-(bipy)3]X3. The kinetics of this reaction was also investigated in the pH range 5,5 - 10,5 by measuring the initial velocity, V0, of the increasing concentration of O2 using a Warburg respirometer. The reaction proceeds according the catalase-like mechanism. On the basis of the results of Sigel et al., the reaction mechanism is discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 575-584 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Metal-4,4′,4″,4″′-tetracarboxyphthalocyanine [Metal = Fe(III), Co(II), Mt-taPc] were synthesized by the hydrolysis of metal-4,4′,4″,4″′-tetracarboxamidephthalocyanine (Mt-tamPc). These metal-taPc are soluble in water and in aprotic polar solvents such as N,N′-dimethylformamide. Poly(styrene) bonded Mt-taPc was synthesized by Friedel-Crafts reaction of poly(styrene) with Mt-taPc tetraacid chloride. The polymers contain about 4 mole-% Mt-Pc rings which are covalently bonded to poly(styrene). The decomposition reaction of hydrogen peroxide by catalysis with polystyrene containing Mt-Pc rings was carried out in heterogeneous aqueous media at pH 7,0. The polymer catalysts show a catalase-like activity. The activation energies with the polymer bonded Mt-Pc were found to be about half of those with Mt-taPc. From continuous flow experiments in a column, the polymer attached catalyst was found to be very stable, compared with free Mt-taPc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 595-633 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A number of tetra- and pentaalkylpiperidine derivatives of acrylic and methacrylic acid was synthesized, polymerized, and copolymerized with several comonomers as potential UV stabilizers. In addition, by oxidation of some of these polymers and of a copolymer with peroxy compounds, polymers were obtained containing pendant nitroxyl groups. The properties of these polymers with free radical groups are discussed in relation to their spectral data.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...