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Impact of anionic polyacrylamide on stability and surface properties of the Al₂O₃-polymer solution system at different temperatures.

ABSTRACT: The stability mechanism and thermal properties of the system alumina-anionic polyacrylamide (PAM) was studied. The polymer's adsorption properties in dependence on the following parameters solution pH (in the range 3-9), temperature (in the range 15-35 °C), and carboxyl groups' content in the PAM chains (in the range 5-30 %) were examined. The turbidimetry method was applied for determination of the suspension stability of alumina in the presence of PAM. The obtained results indicate that the polymer addition improves significantly Al₂O₃ suspension stability at pH 6 and 9 (in the whole examined temperature range). PAM containing a larger number of carboxyl groups stabilizes solid particles more effectively (due to greater contribution of electrosteric interactions). Moreover, the polymer adsorption on the alumina surface causes changes in the thermal stability of the examined systems. In dependence on temperature, the higher the content of carboxyl groups in the PAM molecules, the greater the total mass loss. This is due to increased adsorption of polyacrylamide whose chains contain numerous -COOH groups.

SUBMITTER: Wisniewska M

PROVIDER: S-EPMC4978783 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Impact of anionic polyacrylamide on stability and surface properties of the Al<sub>2</sub>O<sub>3</sub>-polymer solution system at different temperatures.

Wiśniewska Małgorzata M Chibowski Stanisław S Urban Teresa T Sternik Dariusz D Terpiłowski Konrad K

Colloid and polymer science 20160709

The stability mechanism and thermal properties of the system alumina-anionic polyacrylamide (PAM) was studied. The polymer's adsorption properties in dependence on the following parameters solution pH (in the range 3-9), temperature (in the range 15-35 °C), and carboxyl groups' content in the PAM chains (in the range 5-30 %) were examined. The turbidimetry method was applied for determination of the suspension stability of alumina in the presence of PAM. The obtained results indicate that the po ...[more]

PMID: 27546950

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Project description:The absorption and fluorescence spectra of substituted coumarins (2-oxo-2H-chromenes) were investigated in solvents and in polymer matrices. The substitutions involved were: (1) by groups with varying electron donating ability such as CH₃, OCH₃ and N(CH₃)₂, mainly, but not exclusively, in positions 7 and (2), by either CHO or 4-PhNHCONHN=CH- in position 3. While the spectra of non-substituted coumarin-3-carbaldehyde has absorptions at approximately 305 and 350 nm, substitution at position 7 leads to remarkable changes in the shape of the absorption spectrum and shifts the absorption to a longer wavelength. Similarly, the replacement of the formyl group with a semicarbazide group substantially influences the shape of the absorption spectrum, and coumarins which have only N(CH₃)₂ in position 7 experience small changes. These changes are associated with the increasing intramolecular charge transfer (ICT) character and increasing conjugation length of the chromophoric system, respectively, in the studied molecules. The fluorescence is almost negligible for derivatives which have H in this position. With increasing electron donating ability, and the possibility of a positive mesomeric (+M) effect of the substituent in position 7 of the coumarin moiety, the fluorescence increases, and this increase is most intense when N(CH₃)₂ substitutes in this position, for both 3-substituted derivatives. Spectral measurements of the studied coumarins in polymer matrices revealed that the absorption and fluorescence maxima lay within the maxima for solvents, and that coumarins yield more intense fluorescence in polymer matrices than when they are in solution. The quantum yield of derivatives which have a dimethylamino group in position 7 in polymer matrices approaches 1, and the fluorescence lifetime is within the range of 0.5-4 ns. The high quantum yield of 7-dimethylamino derivatives qualifies them as laser dyes which have k(F) higher than k(nr) in the given medium. This is caused by stiffening of the coumarin structure in polar polymer matrices, such as PMMA and PVC, due to higher micro-viscosity than in solution and intermolecular dipole-dipole interaction between chromophore (dopant) and matrix.

Dataset Information

Impact of anionic polyacrylamide on stability and surface properties of the Al₂O₃-polymer solution system at different temperatures.

Publications

Impact of anionic polyacrylamide on stability and surface properties of the Al<sub>2</sub>O<sub>3</sub>-polymer solution system at different temperatures.

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Dataset Information

Impact of anionic polyacrylamide on stability and surface properties of the Al2O3-polymer solution system at different temperatures.

Publications

Impact of anionic polyacrylamide on stability and surface properties of the Al<sub>2</sub>O<sub>3</sub>-polymer solution system at different temperatures.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

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Impact of anionic polyacrylamide on stability and surface properties of the Al₂O₃-polymer solution system at different temperatures.