The effect of mixing and consistency on cellulose cationization.

Traditional chemical modifications of cellulose are usually done at low or medium consistencies. Processing at high solids content is expected to provide a leap forward in reduction of manufacturing costs such as minimization of chemical use, energy consumption and decreasing processing equipment size, while at the same time increasing reaction efficiency. In this research, high consistency modifications of cellulose were studied through cationization reaction. Four different laboratory scale high consistency reactors were tested and the effect of mixing on fiber properties was analyzed. All reactors decreased cellulose fiber length and no significant difference between cellulose starting consistencies and mixing time on fiber properties were found. The cationization reaction efficiency increased as the cellulose starting consistency increased in all of the tested reactors. In addition, mercerization of pulp as pretreatment, significantly increased reaction efficiency.

Suberin Fatty Acids from Outer Birch Bark: Isolation and Physical Material Characterization.

The isolation and physical material properties of suberin fatty acids (SFAs) were investigated with special reference to their potential applications as novel pharmaceutical excipients. SFAs were isolated from outer birch bark (OBB) with a new extractive hydrolysis method. The present simplified isolation process resulted in a moderate batch yield and chemical purity of SFAs, but further development is needed for establishing batch-to-batch variation. Cryogenic milling was the method of choice for the particle size reduction of SFAs powder. The cryogenically milled SFAs powder exhibited a semicrystalline structure with apparent microcrystalline domains within an amorphous fatty acids matrix. The thermogravimetric analysis (TGA) of SFAs samples showed a good thermal stability up to 200 °C, followed by a progressive weight loss, reaching a plateau at about 95% volatilization at about 470 °C. The binary blends of SFAs and microcrystalline cellulose (MCC; Avicel PH 101) in a ratio of 25:75 (w/w) displayed good powder flow and tablet compression properties. The corresponding theophylline-containing tablets showed sustained or prolonged-release characteristics. The physicochemical and bulk powder properties of SFAs isolated from OBB are auspicious in terms of potential pharmaceutical excipient applications.