Influence of the degree of polymerization on the behavior of cellulose during homogenization and extrusion/spheronization.

Abstract

The study objective was to investigate the influence of the degree of polymerization (DP) of cellulose materials (microcrystalline cellulose [MCC] and powder cellulose [PC]) on the behavior of these materials during homogenization and extrusion/spheronization processes. Suspensions of the cellulose types with different DP values were homogenized using a high-pressure homogenizer. The particle size, agglomeration index, and apparent viscosity of these suspensions was determined at different times after pouring. Additionally, these different cellulose types were processed into pellets using the extrusion/spheronization method, and the water content and power consumption as a function of the DP were determined. Cellulose types with a high DP value showed greater particle size after homogenization than the types with a low DP value. In contrast, no relevant relationship between the apparent viscosity and DP could be observed. During the extrusion process, water content in the extrudate and pellet porosity were increased as the DP was increased for the extrudates produced at the same level of power consumption. MCC types with various DPs compared with PC provided a novel way of understanding the role of cellulose in the extrusion process. The DP showed a remarkable influence on the physicochemical properties of the cellulose materials and, consequently, on the behavior of these materials during the extrusion/spheronization process. It is postulated that the sponge model is more appropriate for the cellulose type with high DP (PC), whereas the gel model is more applicable to cellulose types with lower DP (MCC).