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Expansion, morphological, and mechanical properties of starch-polystyrene foams containing various additives / Heartwin A. Pushpadass in Industrial & engineering chemistry research, Vol. 47 n°14 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4736-4742 Titre : Expansion, morphological, and mechanical properties of starch-polystyrene foams containing various additives Type de document : texte imprimé Auteurs : Heartwin A. Pushpadass, Auteur ; Robert W. Besant, Auteur ; Milford A. Hanna, Auteur Année de publication : 2008 Article en page(s) : p. 4736-4742 Note générale : Bibliogr. p. 4742 Langues : Anglais (eng) Mots-clés : Starch−polystyrene  --  expansion;  Azodicarbonamide Résumé : Starch and polystyrene (PS) were mixed at 70:30, 80:20, and 85:15 ratios with 0.5 and 1% talc and extruded into loose-fill packaging foams. Azodicarbonamide (ADC), at 0, 0.2, and 0.4 wt %, and citric acid, at 0, 0.25, and 0.5%, were added as blowing agents to enhance the radial expansion and functional properties of foams. As the concentration of ADC in the starch−PS mixtures was increased from 0 to 0.2%, the expansion ratios increased, and consequently the bulk densities decreased. However, with a further increase in the concentration of ADC to 0.4%, the expansion ratios dropped considerably. The effects of citric acid on radial expansion and other properties were similar to those of ADC. Compared to ADC, citric acid produced foams with higher radial expansion and correspondingly lower densities. Extrudates containing citric acid had large-sized cells, but the cell walls were structurally damaged due to degradation of starch. The spring indices of foams treated with various additives were not significantly different, indicating that spring index may not be a reliable measure of the elasticity. On the other hand, compressibility and modulus of elasticity varied depending on the starch, talc, and blowing agents. Foams extruded with ADC were superior in terms of their cushioning ability and other functional properties. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071049h [article] Expansion, morphological, and mechanical properties of starch-polystyrene foams containing various additives [texte imprimé] / Heartwin A. Pushpadass, Auteur ; Robert W. Besant, Auteur ; Milford A. Hanna, Auteur . - 2008 . - p. 4736-4742. Bibliogr. p. 4742 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4736-4742 Mots-clés : Starch−polystyrene  --  expansion;  Azodicarbonamide Résumé : Starch and polystyrene (PS) were mixed at 70:30, 80:20, and 85:15 ratios with 0.5 and 1% talc and extruded into loose-fill packaging foams. Azodicarbonamide (ADC), at 0, 0.2, and 0.4 wt %, and citric acid, at 0, 0.25, and 0.5%, were added as blowing agents to enhance the radial expansion and functional properties of foams. As the concentration of ADC in the starch−PS mixtures was increased from 0 to 0.2%, the expansion ratios increased, and consequently the bulk densities decreased. However, with a further increase in the concentration of ADC to 0.4%, the expansion ratios dropped considerably. The effects of citric acid on radial expansion and other properties were similar to those of ADC. Compared to ADC, citric acid produced foams with higher radial expansion and correspondingly lower densities. Extrudates containing citric acid had large-sized cells, but the cell walls were structurally damaged due to degradation of starch. The spring indices of foams treated with various additives were not significantly different, indicating that spring index may not be a reliable measure of the elasticity. On the other hand, compressibility and modulus of elasticity varied depending on the starch, talc, and blowing agents. Foams extruded with ADC were superior in terms of their cushioning ability and other functional properties. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071049h

Simulation of moisture uptake and transport in a bed of urea particles / Xiao-Dong Nie in Industrial & engineering chemistry research, Vol. 47 N°20 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7888-7896 Titre : Simulation of moisture uptake and transport in a bed of urea particles Type de document : texte imprimé Auteurs : Xiao-Dong Nie, Auteur ; Richard W. Evitts, Auteur ; Robert W. Besant, Auteur Année de publication : 2008 Article en page(s) : P. 7888-7896 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Granular  urea  Moisture Résumé : Granular urea is a commonly used fertilizer, and it is subject to caking when exposed to small quantities of moisture. In this paper, coupled heat and moisture transport equations are used to predict one-dimensional temperature and moisture content distributions in a bed of bulk granular urea particles when humid air flows uniformly through the bed. The moisture sorption and transport processes consider two computational domains—water vapor diffusion inside each particle and water vapor convection and diffusion in the interstitial air space in the urea particle bed. For energy transport, the temperature is assumed to be uniform inside each particle, but convective heat transfer and conduction between the urea particles and the interstitial air outside particles occur throughout the bed. Comparisons between simulations and data show agreement within the experimental uncertainties for low Reynolds number conditions, where both internal particle and external bed sorption processes are important for porous urea particles in bulk storage. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701744g [article] Simulation of moisture uptake and transport in a bed of urea particles [texte imprimé] / Xiao-Dong Nie, Auteur ; Richard W. Evitts, Auteur ; Robert W. Besant, Auteur . - 2008 . - P. 7888-7896. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7888-7896 Mots-clés : Granular  urea  Moisture Résumé : Granular urea is a commonly used fertilizer, and it is subject to caking when exposed to small quantities of moisture. In this paper, coupled heat and moisture transport equations are used to predict one-dimensional temperature and moisture content distributions in a bed of bulk granular urea particles when humid air flows uniformly through the bed. The moisture sorption and transport processes consider two computational domains—water vapor diffusion inside each particle and water vapor convection and diffusion in the interstitial air space in the urea particle bed. For energy transport, the temperature is assumed to be uniform inside each particle, but convective heat transfer and conduction between the urea particles and the interstitial air outside particles occur throughout the bed. Comparisons between simulations and data show agreement within the experimental uncertainties for low Reynolds number conditions, where both internal particle and external bed sorption processes are important for porous urea particles in bulk storage. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701744g