20 research outputs found
Effect of the acrylic acid content on the permeability and water uptake of latex films
Acrylic acid (AA) is a monomer commonly employed in emulsion polymerization
to provide electrostatic colloidal stability and improve specific film
performance. The addition of AA not only modifies the kinetics of the
polymerization, but also it takes part in the interaction between colloidal
particles, which has a strong influence on their packing and consequent latex
film properties. In this contribution a theoretical modeling of the latex film
formation is presented and compared to experimental results: water vapor
permeability and latex film capacitance are studied as a function of AA
content. It has been shown that water uptake is mainly affected by film
morphology which in turn is defined by intercolloidal interaction and drying
rate.Comment: 16 pages, 7 figure
Morphology and elasticity of waterborne acrylic pressure-sensitive adhesives investigated with atomic force microscopy
Comparative Baeyer-Villiger oxidation of cyclohexanone on Fe-pillared clays and iron tetrasulfophthalocyanine covalently supported on silica
Belaroui, Lala Setti Sorokin, Alexander B. Figueras, Francois Bengueddach, Abdelkader Millet, Jean-Marc M.The Baeyer-Villiger oxidation of cyclohexanone to caprolactone has been investigated at room temperature over AlFe-pillared clays, using oxygen as oxidant in the presence of benzaldehyde. A nearly complete conversion is observed with a selectivity into caprolactone above 80%. The observation of an induction period in the kinetics, of high activity of the non-pillared clay, and the detection of Fe traces in the reaction medium, suggest a process involving homogenous catalysis. The reaction is indeed catalysed in homogeneous phase by a few ppm of Fe. By contrast, iron phthalocyanine covalently supported on silica appears as a true heterogeneous catalyst, giving a selectivity above 95% to caprolactone at 61% conversion. (C) 2010 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved