Influence of Carboxyl Charge Density on Properties of Extruded Cellulose Films

Abstract

Modified pure cellulose-based films were prepared via a scalable process by cellulose carboxymethylation, producing an alkaline dope and flow casting through a slit in an acid bath, followed by washing and drying. The effect of different carboxyl charge densities (0.9, 1.5, and 2.5 mmol/g) on several properties of the films was investigated. Fourier transform infrared and nuclear magnetic resonance spectroscopy showed the formation of carboxyl bonds on cellulose. However, more carboxyl charge caused more fiber dissolution, which greatly affected physical and mechanical properties of the films. It was found that the most transparent, stretchable, moisture absorbent, and densest films were produced with a 2.5 mmol/g charge density, while the highest tenacity and lowest water vapor permeation was measured for 1.5 mmol/g films. Overall, this straightforward procedure can be applied for the fabrication of biodegradable, recyclable, water insoluble, and strong films, a great promising alternative to plastics for packaging.