Physicochemical design of the morphology and ultrastructure of cellulose beads

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• 作者：Jani Trygg^a ; ^{jtrygg@abo.fi} ; Pedro Fardim^a ; Martin Gericke^a ; Ermei M&auml ; kil&auml ; ^b ; Jarno Salonen^b
• 关键词：Cellulose beads ; Dissolution ; Coagulation ; NaOH&ndash ; urea ; Structure design
• 刊名：Carbohydrate Polymers
• 出版年：2013
• 出版时间：1 March, 2013
• 年：2013
• 卷：93
• 期：1
• 页码：291-299
• 全文大小：1953 K

文摘

Cellulose was dissolved in NaOH-urea-water and beads were prepared by coagulation into nitric acid as well as saline solution. Morphology and ultrastructure of the beads were modified by controlling the molarity of the acid (0-10 M) and temperature (5-50 ¡ãC) of the coagulation media and the cellulose concentration (3-7 % ). The beads were characterized by optical image analysis (shape, volume, and size distribution) and weight (total porosity). Cross-sections of CO₂ critical point dried beads were studied by field emission scanning electron microscopy (FE-SEM) and specific surface areas of 336-470 m² g^?1 were determined from nitrogen adsorption isoterms. Pore size distribution was analyzed using solute exclusion technique. Our results demonstrate that the ultrastructure can be controlled by alteration of the coagulation conditions. Changes in size, shape and surface area were substential. Also generation of micro- (?2 ?), meso-, or macropores (?50 ?) can be favored.