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Papers by Rahul Pal
Journal of Non-crystalline Solids, 2009
An acidic silica sol (35 ± 2 wt% equivalent SiO 2 ) having a gelling time of 9-10 min has been us... more An acidic silica sol (35 ± 2 wt% equivalent SiO 2 ) having a gelling time of 9-10 min has been used as an aqueous phase for obtaining a w/o emulsion in CCl 4 as oil phase in presence of a surfactant, Tween 80. The silica sol was allowed to form gel at room temperature via polycondensation among the -Si-OH groups forming the porous silica gel microspheres. The surface area of the microspheres heated at 500°, 700°and 900°C was found to be 227 m 2 /g, 167 m 2 /g and 81 m 2 /g indicating the gradual densification. The decreased surface area and unchanged -Si-O-Si-asymmetric stretching vibration at 1084 cm À1 up to 700°C probably indicate the formation of extensive cross-linked gel structure in the microsphere. The appearance of the -Si-O-Si-asymmetric stretching vibration at 1104 cm À1 and the absence of porosity while heating at 1000°C indicate the formation of dense silica glass microspheres.
Journal of Non-crystalline Solids, 2009
An acidic silica sol (35 ± 2 wt% equivalent SiO 2 ) having a gelling time of 9-10 min has been us... more An acidic silica sol (35 ± 2 wt% equivalent SiO 2 ) having a gelling time of 9-10 min has been used as an aqueous phase for obtaining a w/o emulsion in CCl 4 as oil phase in presence of a surfactant, Tween 80. The silica sol was allowed to form gel at room temperature via polycondensation among the -Si-OH groups forming the porous silica gel microspheres. The surface area of the microspheres heated at 500°, 700°and 900°C was found to be 227 m 2 /g, 167 m 2 /g and 81 m 2 /g indicating the gradual densification. The decreased surface area and unchanged -Si-O-Si-asymmetric stretching vibration at 1084 cm À1 up to 700°C probably indicate the formation of extensive cross-linked gel structure in the microsphere. The appearance of the -Si-O-Si-asymmetric stretching vibration at 1104 cm À1 and the absence of porosity while heating at 1000°C indicate the formation of dense silica glass microspheres.
Journal of Non-crystalline Solids, 2009
An acidic silica sol (35 ± 2 wt% equivalent SiO 2 ) having a gelling time of 9-10 min has been us... more An acidic silica sol (35 ± 2 wt% equivalent SiO 2 ) having a gelling time of 9-10 min has been used as an aqueous phase for obtaining a w/o emulsion in CCl 4 as oil phase in presence of a surfactant, Tween 80. The silica sol was allowed to form gel at room temperature via polycondensation among the -Si-OH groups forming the porous silica gel microspheres. The surface area of the microspheres heated at 500°, 700°and 900°C was found to be 227 m 2 /g, 167 m 2 /g and 81 m 2 /g indicating the gradual densification. The decreased surface area and unchanged -Si-O-Si-asymmetric stretching vibration at 1084 cm À1 up to 700°C probably indicate the formation of extensive cross-linked gel structure in the microsphere. The appearance of the -Si-O-Si-asymmetric stretching vibration at 1104 cm À1 and the absence of porosity while heating at 1000°C indicate the formation of dense silica glass microspheres.
Journal of Non-crystalline Solids, 2009
An acidic silica sol (35 ± 2 wt% equivalent SiO 2 ) having a gelling time of 9-10 min has been us... more An acidic silica sol (35 ± 2 wt% equivalent SiO 2 ) having a gelling time of 9-10 min has been used as an aqueous phase for obtaining a w/o emulsion in CCl 4 as oil phase in presence of a surfactant, Tween 80. The silica sol was allowed to form gel at room temperature via polycondensation among the -Si-OH groups forming the porous silica gel microspheres. The surface area of the microspheres heated at 500°, 700°and 900°C was found to be 227 m 2 /g, 167 m 2 /g and 81 m 2 /g indicating the gradual densification. The decreased surface area and unchanged -Si-O-Si-asymmetric stretching vibration at 1084 cm À1 up to 700°C probably indicate the formation of extensive cross-linked gel structure in the microsphere. The appearance of the -Si-O-Si-asymmetric stretching vibration at 1104 cm À1 and the absence of porosity while heating at 1000°C indicate the formation of dense silica glass microspheres.