Development of cellulosic bioplastic-based biocomposites for biodegradable packaging applications: Effect of high acetyl content and high filler loading

Cellulosic plastics have attained significant interest as a result of their biodegradability and biocompatibility. Accordingly, this work explores the influence of inorganic fillers (mineral fillers) on cellulosic plastic (plasticized cellulose acetate (pCA)) to evaluate its potential as a sustainable substitute to conventional petroleum-based plastics for rigid packaging. Cellulose acetate (CA) was plasticized using an eco-friendly plasticizer, triacetin, which broadened the narrow processing window of CA and helped in achieving stable melt extrusion. The addition of Luperox® (organic peroxide) further facilitated process stability during melt compounding. The composites were processed via extrusion followed by injection molding. Calcium carbonate (CaCO3), kaolin and talc, were incorporated as fillers and their influence on the thermal, mechanical, rheological, dimensional and barrier properties of pCA composites were analyzed. Talc outperformed all the inorganic fillers, demonstrating an increase in tensile modulus (127%), tensile strength (21%), flexural modulus (87%), flexural strength (29%), and barrier properties (water vapor barrier by ~60% and oxygen barrier by 58%). The heat deflection temperature of pCA matrix increased as a result of reinforcing with talc. Dimensional stability was also improved, as observed by a reduction in the coefficient of linear thermal expansion by 22% in the normal direction and 29% in the flow direction in comparison to neat pCA. Furthermore, rheology and morphological analysis reflected strong filler-matrix interactions. These findings highlight the potential of pCA-based composites in advancing the use of biodegradable and sustainable materials for rigid packaging applications.