Fig. 14 SEM of free film prepared from an aqueous dispersion of LCC. provides high surface energy for interaction with water molecules. As water evaporates during drying, fine particles of LCC are forced together, deformed, interacted, and coalesced into a film. LCC dispersions containing 3% or lower solids are physically unstable, unless stabilized with a secondary soluble polymer. The aqueous dispersions can be converted into a fine powder (LCPC) or a bead form (LCBC) by using conventional dehydration and spray-drying techniques. The crystallinity of LCPC powder versus its hydrated form is compared in Fig. 15. It ap-

doi:10.1201/9781420000955-30

Chapter

Fig. 14 SEM of free film prepared from an aqueous dispersion of LCC. provides high surface energy for interaction with water molecules. As water evaporates during drying, fine particles of LCC are forced together, deformed, interacted, and coalesced into a film. LCC dispersions containing 3% or lower solids are physically unstable, unless stabilized with a secondary soluble polymer. The aqueous dispersions can be converted into a fine powder (LCPC) or a bead form (LCBC) by using conventional dehydration and spray-drying techniques. The crystallinity of LCPC powder versus its hydrated form is compared in Fig. 15. It ap-

Chapter

Fig. 14 SEM of free film prepared from an aqueous dispersion of LCC. provides high surface energy for interaction with water molecules. As water evaporates during drying, fine particles of LCC are forced together, deformed, interacted, and coalesced into a film. LCC dispersions containing 3% or lower solids are physically unstable, unless stabilized with a secondary soluble polymer. The aqueous dispersions can be converted into a fine powder (LCPC) or a bead form (LCBC) by using conventional dehydration and spray-drying techniques. The crystallinity of LCPC powder versus its hydrated form is compared in Fig. 15. It ap-

ABSTRACT

Recently, oxidized celluloses that readily disperse in water to form colloids have been prepared using alkali and alkaline earth metal hypohalites and persulfates [64-66]. The white to off-white powder when suspended in water forms a stable colloidal or near colloidal thixotropic dispersion. The particle size distribution of an oxidized cellulose dispersion prepared using hypohalite is shown in Fig. 16 [66]. A wide variety of solid (crystalline or amorphous) and liquid bioactive compounds can be entrapped and loaded in such systems, thereby producing substantive controlled and/or sustained release formulations, having unique applications for the development of cosmetic, pharmaceutical, agricultural, and consumer products. The most effective plasticizer is glycerin. Appropriately plasticized aqueous colloidal systems of oxidized cellulose can be cast to develop transdermal patches or used to produce films or matrices. A scanning electron photomicrograph of a film produced from an oxidized cellulose dispersion plasticized with glycerin is shown in Fig. 17. Although the dispersions are microbiologically stable for several months, preservatives such as benzoates should be added to the dispersion to prevent and/or inhibit microbial growth.