Development of renewable resource-based cellulose acetate bioplastic: Effect of process engineering on the performance of cellulosic plastics

This paper deals with the development of a cellulose acetate biopolymer. Plasticization of this biopolymer under varying processing conditions to make it a suitable matrix polymer for bio-composite applications was studied. In particular, cellulose acetate was plasticized with varying concentrations of an eco-friendly triethyl citrate (TEC) plasticizer, unlike a conventional, petroleum-derived phthalate plasticizer. Three types of processing were used to fabricate plasticized cellulose acetate parts: compression molding, extrusion followed by compression molding, and extrusion followed by injection molding. The processing mode affected the physicomechanical and thermal properties of the cellulosic plastic. Compression molded samples exhibited the highest impact strength, tending towards the impact strength, of a thermoplastic olefin (TPO), while samples that were extruded and then injection molded exhibited the highest tensile strength and modulus values. Increasing the plasticizer content in the cellulosic plastic formulation improved the impact strength and strain to failure while decreasing the tensile strength and modulus values. The coefficient of thermal expansion (CTE) of the cellulose acetate increased with increasing amounts of plasticizer. Plasticized cellulose acetate was found to be processable at 170 - 180degreesC, approximately 50degreesC below the melting point of neat cellulose acetate.