# Development of Cellulose Acetate Spherical Microparticles by Means of Melt Extrusion of Incompatible Polymer Blend

## TL;DR

This study explores creating cellulose acetate microparticles using melt extrusion, aiming to address microplastic pollution.

## Contribution

A method to produce CA microparticles with controlled size and surface using incompatible polymer blends is developed.

## Key findings

- CA microparticles with sizes 2–8 μm and smooth surfaces were successfully produced.
- The RMSE between observed and calculated particle sizes was 4.46 μm, indicating prediction limitations.
- TA migration between phases was identified as a possible cause for prediction inaccuracies.

## Abstract

Cellulose acetate (CA), commercially produced from natural cellulose, is one of the promising candidates to solve the microplastic issue. In this study, attempts were made to prepare CA microparticles by means of melt extrusion of incompatible polymer blends comprising CA with plasticizer (triacetin (TA)) and polyvinyl alcohol (PVA) followed by selective removable of TA and PVA. As implied by semi-theoretical equation previously established by Wu (Wu’s equation), particle size decreased with increasing shear rate or decreasing viscosity ratio of polymers. CA microparticles with a controlled size of 2–8 μm, narrow particle size distribution, and smooth surface were successfully obtained. Efforts were made to determine the numerical solution of Wu’s equation to compare them with observed particle size. To this end, interfacial tension between dispersed and matrix phases to be incorporated in the equation was determined by group contribution methods. The root mean squared error (RMSE) between the observed and calculated particle size was unsatisfactorily large, 4.46 μm. It was found that one of the possible reasons for the limited prediction accuracy was migration of TA from the dispersed to matrix phase affecting the viscosity ratio. Further efforts will be required to achieve a better prediction.