Biodegradable nanocomposites from cellulose acetate: Mechanical, morphological, and thermal properties

Abstract

Environmentally benign nanocomposites were synthesized using cellulose acetate (CA) bioplastic, citrate based plasticizer and organically modified clay nanofillers to eventually substitute the existing petroleum-based polypropylene/thermoplastic olefins (PP/TPO) based composites in automotive applications. Method of processing, amount of clay, and processing conditions were thoroughly investigated to make exfoliated and/or intercalated clay/CA nanocomposites. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) revealed the existence of intercalated clay dispersed throughout the CA matrix. The intercalated reinforcements resulted in enhancements of the composite tensile strength, tensile modulus, coefficient of thermal expansion (CTE), and heat deflection temperature (HDT). The composite tensile strength of CA increased approximately 38% after incorporating 5 wt% clay. The tensile modulus was also enhanced as much as 33%. The HDT of CA plastics slightly increased as a result of reinforcing with the clay nanofiller. A slight reduction in CTE value was observed after addition of 5% clay. A moderate interfacial region resulting from curve fitting of experimental tensile modulus data vs. three-phase model suggested a moderate adhesion between clay and CA matrix. Our future research direction is to utilize an appropriate compatibilizer to enhance the miscibility between the clay and the matrix so as to improve adhesion and thus enhance mechanical and thermal properties.