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  • 1995-1999  (4)
  • 1985-1989  (19)
  • Chemistry  (23)
  • 1
    Digitale Medien
    Digitale Medien
    Studies on polymerization of vinyl acetate using ylide as an initiator and degradative transfer agent (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 807-815 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Polymerization of vinyl acetate initiated by β-picolinium p-chlorophenacylide was carried out at 30, 35, and 40°C, using conventional dilatometric technique. The initiator and the monomer exponent values were 0.80 ± 0.15 and unity, respectively. The polymerization was inhibited in the presence of hydroquinone, but was favored by nonpolar solvent and polymerization temperature. The energy of activation was 90.3 KJ mol-1. An average value of kp2/kt for the present system was found to be 0.37 × 10-2. The results are explained in terms of a radical mode of polymerization with degradative initiator transfer; the principal mode of termination, however, was bimolecular.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1989.080270306
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  • 2
    Digitale Medien
    Digitale Medien
    Studies on polymerization of vinyl acetate using ylide as an initiator and degradative transfer agent (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 43-51 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The polymerization of vinyl acetate initiated by β-picolinium-p-chlorophenacylide was carried out at 30, 35, and 40°C, using the conventional dilatometric technique. The initiator and the monomer exponent values were 0.80 ± 0.15 and unity, respectively. The polymerization was inhibited in the presence of hydroquinone, but was favored by nonpolar solvent and polymerization temperature. The energy of activation was 90.3 kJ mol-1. An average value of kp2/kt for the present system was found to be 0.37 × 10-2 L mol-1 s-1. The results are explained in terms of radical mode of polymerization with degradative initiator transfer; the principal mode of termination, however, was biomolecular.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1989.080270104
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  • 3
    Digitale Medien
    Digitale Medien
    Poly(vinyl acetate) as a template for the radical polymerization of acrylonitrile (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 1065-1070 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The template polymerization of acrylonitrile (AN) along with atactic-poly(vinyl acetate) of Mv (47,090), at 60°C for 120 min in dimethyl formamide (DMF) has been studied dilatometrically to study the effects of template, monomer, and initiator (benzoyl peroxide) concentration upon kinetics. Viscometric measurements showed that complexation between at-PVAc and PAN was maximum when template/polymer ratio was 1:1 and time required for complete complexation was 15 min. The overall energy of activation was 57.76 and 77.01 kJ/mol in the presence and absence of, PVAc, respectively. The overall system follows mechanism I, i.e., the monomer molecules get adsorbed on the surface of the template macromolecules and then propagation proceeds.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1989.080270328
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  • 4
    Digitale Medien
    Digitale Medien
    Radical polymerization of styrene initiated by styrene-arsenic sulfide complex (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 3811-3816 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Styrene forms a complex with arsenic sulfide which in DMF at 85°C initiates radical polymerization yielding high molecular weight polymer. The order of reaction, with respect to initiator and monomer, is 0.5 ± 0.02 and unity, respectively. The energy of activation for the system computed as 96 kJ mol-1 and the polymerization is retarded by hydroquinone. A possible mechanism for reaction has also been proposed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1989.080271121
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  • 5
    Digitale Medien
    Digitale Medien
    p-acetyl benzylidene triphenylarsonium ylide initiated radical terpolymerization of styrene, acrylonitrile and copper acrylate: synthesis, characterization and properties (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 41 (1996), S. 407-412 
    Details
    ISSN: 0959-8103
    Schlagwort(e): terpolymerization ; kinetics ; thermal properties ; arsonium ylide ; styrene ; acrylonitrile ; copper acrylate ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Solution terpolymerization of styrene (Sty), acrylonitrile (AN) and copper acrylate (CuA) has been carried out in dimethylformamide at 90°C for 4 h using p-acetyl benzylidene triphenylarsonium ylide as radical initiator. 1H nuclear magnetic resonance (NMR), IR and elemental analysis have been used to characterized the terpolymer. Analysis of kinetic data indicates the following rate equation: $$R_{\rm p} \propto \left[ {{\rm ylide}} \right]^{0.5} \left[ {{\rm Sty}} \right]\left[ {{\rm AN}} \right]{1 \over {\left[ {{\rm CuA}} \right]}}$$ The overall activation energy is 38 kJ mol-1. The composition of terpolymer calculated from NMR and elemental analysis has been used to evaluate reactivity ratios as r1(Sty) = 5 ± 2 and r2(AN + CuA) = 0.4 ± 0.02 employing the Finemann-Ross method, which confirms its random origin. The terpolymer was thermally stable up to 2007deg;C.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Effect of sulfur mustard on microhardness of poly(ethylene terephthalate) films (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 147-151 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effect of sulfur mustard (SM), a well-known chemical warfare agent on the microhardness of two poly(ethylene terephthalate) (PET) films was investigated at different loads. SM induces hardness in PET films, perhaps due to an antiplasticizing effect. Heat treatment of the films enhanced their microhardness. The heat-set films show a further increase in their microhardness after exposure to SM. These results were supported by physicochemical techniques like plasma and amine etching, which revealed complex etching phenomena giving rise to a structure-specific pattern. The film having a higher weight loss due to plasma and amine etching showed lower microhardness. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Studies on the polymerization of methyl methacrylate using ylide as an initiator and degradative transfer agent (1986)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 141 (1986), S. 103-111 
    Details
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die mit α-Picolinium-p-chlorphenacylid initiierte Polymerisation von Methylmethacrylat in Tetrachlorkohlenstoff bei 30, 35 und 40°C und einer Dauer von vier Stunden wurde dilatometrisch untersucht. Die Reaktionsordnungen im Hinblick auf die Konzentration von Ylid und Methylmethacrylat liegen bei 0,22 ± 0,1 bzw. 1,0. Die gesamte Aktivierungsenergie und der mittlere Wert von kp2/kt beträgt 21 kJ · mol-1 bzw. 0,37 · 10-2.Die Ergebnisse wurden als radikalische Polymerisation mit einer initiatorabhängigen Übertragung und einem bimolekularen Abbruch erklärt.
    Notizen: The polymerization of methyl methacrylate (MMA) initiated by α-picolinium-p-chlorophenacylide in CCl4 at 30, 35, and 40°C for four h was investigated dilatometrically. The orders of reaction with respect to the concentrations of ylide and MMA are 0.22 ± 0.01 and 1.0, respectively. The overall energy of activation and an average value of kp2/kt are 21.0 kJmol-1 and 0.37 ± 10-2, respectively. The results are explained in terms of radical mode of polymerization with initiator dependent transfer besides bimolecular termination.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/apmc.1986.051410111
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  • 8
    Digitale Medien
    Digitale Medien
    Studies on β-picolinium-p-chlorophenacylide initiated copolymerization of methyl methacrylate with styrene (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 149 (1987), S. 139-150 
    Details
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die alternierende Copolymerisation von Methylmethacrylat mit Styrol unter Verwendung von β-Picolinum-P-chlorphenacylid als Radikalinitiator bei 55, 60 und 65°C und einer Reaktionszeit von 3 h wurde kinetisch untersucht. Die Copolymerisationsgeschwindigkeit (Rp) ist proportional der Quadratwurzel der Initiatorkonzentration und weist auf einen bimolekularen Abbruch hin. Der durchschnittliche Polymerisationsgrad nimmt mit zunehmender Initiatorkonzentration ab. Die ermittelten Werte für kp2/kt und für die Aktivierungsenergie betragen 1,43 · 10-3 l mol-1 s-1 bzw. 87 kJ mol-1. Die NMR Spektroskopie wurde zur Bestimmung der Struktur, Zusammensetzung und Stereochemie der Copolymeren verwendet.
    Notizen: The alternating copolymerization of methyl methacrylate (MMA) with styrene (S) using β-picolinium-p-chlorophenacylide (β-PCPY) as radical initiator at 55, 60, and 65°C for 3 h has been kinetically investigated. The copolymerization rate (Rp) is proportional to the square root of [β-PCPY] and indicates bimolecular termination. The average degree of polymerization decreases as [β-PCPY] increases. The values of kp2/kt and energy of activation have been evaluated as 1.43 · 10-3 l mol-1 s-1 and 87 kJ mol-1, respectively. The NMR spectroscopy has been used to determine the structure, composition, and stereochemistry of copolymers.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/apmc.1987.051490111
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  • 9
    Digitale Medien
    Digitale Medien
    Polyvinyl acetate as a template for the radical polymerization of methyl methacrylate (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 170 (1989), S. 127-135 
    Details
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Matrizenpolymerisation von Methylmethacrylat (MMA) in Gegenwart von ataktischem Polyvinylacetat (at-PVAC, M̄v = 55 800) bei 60°C in Dimethylformamid (DMF) wurde dilatometrisch gemessen, um die Einflüsse der Konzentration der Matrize, des Monomeren und des Initiators auf die Kinetik zu untersuchen. Die resultierenden Auftragungen der relativen Polymerisationsgeschwindigkeit (VR) gegen die at-PVAC- und MMA-Konzentration zeigen, daß die Polymerisation in diesem System aus einer Kombination von drei verschiedenen Reaktionsmechanismen besteht: die unbeeinflußte Reaktion und zwei Matrizenmechanismen (I und II). Die Reaktionsordnung bezüglich Matrize, Monomerem und Initiator beträgt 0,66, 0,75 und 0,40. Viskosimetrische Messungen zeigten, daß die Komplexierung zwischen at-PVAC und PMMA bei einem Matrize/Polymer-Verhältnis von 1 : 1 am größten war. Die Zeit für eine vollständige Komplexierung betrug 10 min. Die Gesamtaktivierungsenergie betrug 33,5 kJ mol-1 in Gegenwart und 25,0 kJ mol-1 in Abwesenheit von at-PVAC.
    Notizen: The template polymerization of methyl methacrylate (MMA) along with atactic polyvinyl acetate (at-PVAC, M̄v = 55880) at 60°C for 120 min in dimethyl formamide (DMF) has been measured dilatometrically to study the effects of the concentrations of template, monomer, and initiator upon the kinetics. The resulting plots of relative polymerization rate (VR) vs. the at-PVAC- and MMA-concentration showed that in the present system the polymerization is a combination of three different reaction mechanisms, the blank reaction and two template mechanisms (I and II). The order of reaction with respect to template, monomer and initiator is 0.66, 0.75 and 0.40, respectively. Viscometric measurements showed that complexation between at-PVAC and PMMA was maximum when the template/polymer ratio was 1 : 1 and the time required for complete complexation was 10 min. The overall energy of activation was 33.5 and 25.0 kJ mol-1 in the presence and absence of at-PVAC, respectively.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/apmc.1989.051700109
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  • 10
    Digitale Medien
    Digitale Medien
    Representation of culture transition states in A. suboxydans (1998)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 73 (1998), S. 23-30 
    Details
    ISSN: 0268-2575
    Schlagwort(e): vitamin C ; structured mathematical model ; continuous culture kinetics ; sorbose ; sorbitol ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The kinetics of the biotransformation of D-sorbitol to L-sorbose by Acetobacter suboxydans (NRRL B-72) features both substrate and product inhibition. Model-based reactor operating strategies can eliminate the inhibitions and improve the yield and productivity of the fermentation. Unstructured models are usually unable to acknowledge complex intracellular physiological changes and therefore their application to dynamic growth conditions is limited. By considering RNA as a bottleneck growth limiting compound a structured mathematical model was developed to describe the transient growth of Acetobacter suboxydans. The model parameters were determined by a non-linear regression technique which minimized the deviation between the model prediction and the experimental (extracellular and intracellular) continuous culture data. The model was used to simulate the transient culture behaviour during the step-down in the dilution rates (from 0·1 h-1 to 0·05 h-1) in the continuous culture experiments. The experimental results and the model simulation results showed reasonable agreement. © 1998 Society of Chemical Industry
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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