Influence of the surface tension of wet massing liquid on the functionality of microcrystalline cellulose as pelletization aid

Abstract

This study designed to investigate the impact of surface tension of moistening liquid on the functionality of MCC as pelletization aid. For this purpose, sodium dodecyl sulfate (SDS), poloxamer 188 (PL), di-potassium hydrogen phosphate (K2HPO4) and combinations thereof were incorporated into the powder blend comprised of MCC and dicalcium phosphate (DCP) at different levels. Physical mixture (PM) and co-processed composite (Cop) of MCC and sodium carboxymethyl cellulose (SCMC) replaced MCC as pelletization aids. The pellets prepared were characterized for their median diameter (D50), particle size distribution (PSD), sphericity, porosity, tensile strength and disintegration. SDS induced a drop in the surface tension of water from 68.7 to 23.7 mN/m at 0.1% (w/w). In contrast, the surface tension values of PL and K2HPO4 solutions were 2.08- and 3.07-fold higher than that of SDS solutions, respectively. MCC based pellets obtained with SDS showed wider PSD and lower sphericity than those made with PL, K2HPO4 and their combinations. In addition, the PSD and porosity increased with rise of SDS concentration from 0.05 to 0.25% (w/w). It was thus inferred that a critical surface tension of moistening liquid was essential for functionality of MCC as pelletization aid but not for PM and Cop.