Insights into the functionality of pelletization aid in pelletization by extrusion-spheronization

Abstract

This study investigated the particle sizes of pelletization aids from the different wet processing steps of extrusion-spheronization, and their influence on rheological and pellet properties. Three commercial microcrystalline cellulose (MCC) grades, three commercial cross-linked polyvinyl pyrrolidone (X-PVP) grades and two agglomerated X-PVP grades (prepared using roller compaction from two commercial fine particle size X-PVP grades) were used as pelletization aid. The pelletization aids were analyzed for their dry state particle size, individual particle size (sonicated powder dispersion in water) and in-process particle sizes (dispersions of processed materials from the different processing steps). No remarkable particle size changes were observed with the commercial X-PVP grades under the different conditions. The two fine X-PVP grades, but not the coarse grade, produced good quality pellets. MCC and agglomerated X-PVP grades exhibited spectacularly lower individual and in-process particle sizes, and produced good quality pellets although some of them had dry state particle sizes comparable to that of the commercial coarse X-PVP grade. In-process particle sizes of pelletization aids correlated strongly with the rheological and pellet properties of the pelletization aid:lactose (1:3) binary mixtures. These results demonstrated that small in-process particle size of pelletization aid is a critical requirement for successful pelletization by extrusion-spheronization.

Keywords::

• In-process particle
• individual particle
• microcrystalline cellulose
• cross-linked polyvinyl pyrrolidone

Acknowledgement

Camo Inc. (Bangalore, India) is acknowledged for providing the Unscrambler 9.8 software used for the multivariate data analysis.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. Funding for the research is from the National University of Singapore (Grant no.: N-148-000-008-001).