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  • 1
    Electronic Resource
    Electronic Resource
    Structure of reversed micelles in the cyclohexane/polyoxyethylene(4)nonylphenol/water system, as studied by the spin probe technique (1992)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 96 (1992), S. 7109-7115 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100196a051
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  • 2
    Electronic Resource
    Electronic Resource
    The properties of aqueous solutions of some short chain cosurfactants used for radical polymerization of vinyl acetate (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 903-909 
    Details
    ISSN: 1435-1536
    Keywords: Key words Short chain cosurfactants ; refractive index ; excess volume ; polymerization of vinyl acetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The refractive index and excess molar volume, of the following short hydrocarbon chain co-surfactants were studied: ethylene glycol, ethylene glycol monomethyl ether, ethanol, n-, i-propanol, acrylic acid, ethyl monomethylmaleate and acrylamide. The refractive indexes of the aqueous solutions of these compounds vary nonlinearly with composition. The maximum variation of refractive indexes occurs up to a cosurfactant/water molar ratio equal to 1 5. The fluorescence probe method was successfully used to evidence the structure modifications of the alcohol–water mixtures. The intensity ratio of pyrene fluorescence vibrational bands varies nonlinearly with the composition of the systems; in case of 1-propanol, the sudden decrease of the ratio is similar to that of micellar solutions, so that a critical concentration of association can be determined at a 0.88 water mole fraction. It was shown, in good agreement with data in literature, that the compounds mentioned penetrate into the cluster structure of water and associate. At concentrations higher than critical, restructuring of aqueous solutions continues and structures of bicontinuous or w/o type may arise. The excess volume of the first six compounds is negative owing to the restructuring just mentioned. Vinyl acetate may penetrate in the struc-tures of binary systems to form homogeneous systems. The number of homogeneous systems decreases in the sequence: ethanol, i-propanol, acrylic acid, n-propanol, the mono-methylether of ethyleneglycol, methyl monomaleate. The vinyl acetate over cosurfactant molar ratio of limiting homogeneous systems varies in inverse sequence at the same monomer/water ratio. After radical polymerization of VAc in homogeneous samples transparent systems were obtained only when the polymer was solubilized in cosurfactant water mixtures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050165
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  • 3
    Electronic Resource
    Electronic Resource
    Polymerization of vinyl acetate in homogeneous systems obtained in presence of acrylic acid (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 203-209 
    Details
    ISSN: 1435-1536
    Keywords: Key words Microemulsions ; Vinylacetate ; Acrylic acid structure ; Polymerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The composition ranges over which microemulsions are formed in systems containing vinyl acetate, acrylic acid, water with nonylphenol ethoxylated with 25 mol ethylene oxide monomaleate as surfactant were studied. Conductometric and refractometric investigations have shown the existence of some aqueous/organic, bicontinuous and organic/aqueous microemulsions. The types of precursor microemulsions influence the conversion of monomers. In the presence of a crosslinking agent, diethylene glycol bis maleate, hydrogels are formed whose water absorption depends on the composition of the initial microemulsions. The kinetics of water absorption suggests the modification of polymer network structures as a function of the crosslinked monomer content and the ratio of organic to aqueous phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013744
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  • 4
    Electronic Resource
    Electronic Resource
    A study of degradation reaction of hydroxyethylcellulose in presence of potassium persulphate (1980)
    Springer
    Colloid & polymer science 258 (1980), S. 1363-1366 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Hydroxyäthylzellulose (HEC) wird in Gegenwart von Kaliumpersulfat (KPS) oxidativ abgebaut. Als Folge dieser Reaktion spaltet sich die makromolekulare Kette auf, wobei sich Carbonyl-Gruppen bilden. Die Bildung der CarbonylGruppen wurde durch UV-Spektroskopie und der Molekülabbau viskosimetrisch untersucht. Die Zersetzungsgeschwindigkeit des KPS wird durch die Gleichung: $$ - d|KPS|_0 /dt = K|KPS|_0 |HEC|_0^{1/4} $$ beschrieben. In Gegenwart von HEC steigt die Abbaugeschwindigkeit von KPS bemerkenswert an. Die Aktivierungsenergie in Gegenwart von HEC ist 60 kJ/mol.
    Notes: Summary Hydroxyethylcellulose (HEC) undergoes reactions of oxidative degradation in presence of potassium persulphate (KPS). Following this reaction the macromolecular chain splits and carbonyl groups are produced. The formation of carbonyl groups was evidenced by UV spectroscopy, while the scission by viscometry. The rate of decomposition of KPS is given by the equation. $$ - d|KPS|_0 /dt = K|KPS|_0 |HEC|_0^{1/4} .$$ In presence of HEC the decomposition reaction rate of KPS is considerably increased. The activation energy of this reaction in presence of HEC is of 60 KJ/mol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01668784
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  • 5
    Electronic Resource
    Electronic Resource
    Polymerisation of vinyl acetate in microemulsions with methanol (2000)
    Springer
    Colloid & polymer science 278 (2000), S. 927-935 
    Details
    ISSN: 1435-1536
    Keywords: Key words Microemulsions ; Vinyl acetate ; Methanol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The homogeneity domains for the system vinyl acetate – methanol – monomaleate of nonylphenol ethoxylated with 25 mol ethylene oxide as an aqueous solution (MEMNPEO25) (33%) have been studied; it has been shown that, due to the shorter chain of methanol, these domains are more reduced than in the case of ethanol. The changes in refractive indexes and electrical conductivities have shown the formation of microemulsions with different structures (water-in-oil, bicontinuous or oil-in-water). Ammonium persulphate is soluble only in oil-in-water or in bicontinuous microemulsions. The initial polymerisation rates as well as the decomposition rates for the initiator are apparently affected when the microemulsion structure is modified. The polymerisation rate of vinyl acetate is higher in the presence of methanol than in the presence of ethanol for similar compositions; this fact may be attributed to a higher degree of ionisation of the initiator in the presence of methanol. Also, in polymerisations initiated by benzoyl peroxide, the conversions are influenced by the microstructure; thus, the maximum corresponds to water-in-oil microemulsions. By measuring the amount of unreacted MEMNPEO25 (gel permeation chromatography) we were able to show that the copolymer formed consisted of vinyl acetate and reactive surfactant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960000340
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  • 6
    Electronic Resource
    Electronic Resource
    Semicontinuous emulsion polymerization of vinyl acetate IX. Decomposition of the initiatorPart VIII: Acta Polymerica 41 (1990) 210 (1991)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 42 (1991), S. 526-530 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß der Reaktanten im Polymerisationsmedium und der Reaktionsbedingungen auf die Zersetzungsreaktion eines Persulfatinitiators wird untersucht. Die Geschwindigkeit der Spaltungsreaktion von Kaliumpersulfat steigt bei Anwesenheit eines Schutzkolloids und einer oberflächenaktiven Substanz in der wäßrigen Phase. In Gegenwart von Vinylacetat ist die Spaltungsgeschwindigkeit niedriger. Bei Anwesenheit hydrophober nimmt die Zerstzungsgeschwindigkeit des Initiators ab. Ein Anstieg der Zuführungsgeschwindigkeit der Monomere erhöht die Menge an erhaltenem Polymer und die Spaltungsgeschwindigkeit des Initiators.
    Notes: The way in which the decomposition reaction of a persulfate initiator is influenced by the nature of reactants of the polymerization medium and by the working conditions during the semicontinuous polymerization and copolymerization of vinyl acetate is studied. The rate of the splitting reaction of potassium persulfate is higher in the aqueous phase containing a protective colloid and surfactant. The splitting rate is smaller in the presence of vinyl acetate. The presence of hydrophobic commonomers decreases the rate of initiator decomposition. An increase of the addition rate of monomers leads to an increase of the obtained polymer and of the splitting rate of the initiator.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1991.010421013
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  • 7
    Electronic Resource
    Electronic Resource
    Semicontinuous emulsion polymerization of vinyl acetate. IV. Homopolymerization with poly(vinyl alcohol) (1989)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 40 (1989), S. 49-52 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Bei der semikontinuierlichen Emulsionspolymerisation von Vinylacetat verhält sich das System am Anfang des Prozesses wie ein überflutetes System. Danach stellt sich eine Polymerisationsgeschwindigkeit proportional zum zugeführten Monomer ein. Bei mäßiger Zuführungsgeschwindigkeit wird die Polymerisationsgeschwindigkeit von der Zuführungsgeschwindigkeit bestimmt. Bei einer kritischen Zuführungsgeschwindigkeit erfolgt der übergang zu einem Überfluten System. Umsatz und Teilchendurchmesser nehmen mit steigender Rührgeschwindigkeit ab.
    Notes: In semicontinuous emulsion polymerization of vinyl acetate the system behaves as a flooded system in the first moment of the process. Then the polymerization rate becomes proportional to the introduced monomer. At moderate feed rate the polymerization rate is controlled by the addition rate. At a critical addition rate transition to a flooded system takes place. The conversion and particle diameter decrease with increasing stirring speed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1989.010400110
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  • 8
    Electronic Resource
    Electronic Resource
    Semicontinuous emulsion polymerization of vinyl acetate. VIII. Copolymerization with di-2-ethylhexyl maleate (1990)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 41 (1990), S. 210-214 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die semikontinuierliche Emulsionscopolymerisation von Vinylacetat mit 2-Ethylhexylmaleat wurde untersucht. Die Mange des bei kontinuierlicher Zufährung der Comonomere erhaltenen Polymers nimmt mit der Zeit zunächst nichtlinear, dann linear zu. In diesen Stadium des Prozesses ist die Viskosität der entstehenden Emulsion nicht proportional zum Polymerigehalt. Der Umsatz wird durch die Reaktionsbedingungen beeinflußt, z. B. durch die Rührgeschwindigkeit und durch die Menge des als Transfermittel zugegebenen n-Butanols sowie dessen Verteilung zwischen der anfänglichen Reaktorfüllung und den kontinuierlich zugeführten Comonomeren.
    Notes: The semicontinuous emulsions copolymerization of vinyl acetate with 2-ethylhexyl maleate has been studied. The amount of polymer obtained during the continuous addition of commonomers increases at first nonlinearly than linearly with time. During this period the viscosity of the obtained emulsion is not proportional to the polymer content. The conversions are affected by the reaction conditions, e.g. the stirring rate and the amount of the transfer agent n-butanol and its distribution between the initial reactor charge und the continuously introduced comonomers.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1990.010410404
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