Comportamento térmico e mecânico de blendas PLA/PBATcom nanocristais de celulose

Abstract

The use of biodegradable polymers is seen as one of many strategies to minimize the environmental impact generated by improper disposal of plastic packaging. Poly (lactic acid) (PLA) is a biodegradable polymer with high mechanical strength and high modulus of elasticity. Its use is limited due to its low deformation. Poly (butylene adipate co-terephthalate) (PBAT), as a flexible, biodegradable and high tenacity polymer, is suitable for increasing the toughness of the PLA matrix. Cellulose nanocrystals (NCC) present mechanical, optical and thermal properties of great interest to be used as a reinforcing agent in polymer matrices. Thus, this work proposes to evaluate the effect of NCC on the mechanical and thermal behavior of the PLA / PBAT blends. PLA, PBAT, PLA / PBAT (80:20) and PLA / PBAT / NCC films with NCC content ranging from 1% to 6% by mass were prepared by solvent evaporation (casting). These samples were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and by tensile test. The morphology and thermal properties of the PLA / PBAT blends confirmed an immiscibility among their constituents. The morphology of the blends was altered due to the addition of nanocrystals, where contents of up to 2% in mass of NCC showed a subtle reduction of PBAT particle size in the PLA matrix. The melting of the PLA / PBAT blends was not affected by the NCC content. The incorporation of 1 and 2% of nanocrystals increased the tensile strength and modulus of elasticity of the blend. However, there was a drastic fall in the mechanical properties to contents higher than 2%, suggesting a weak interfacial adhesion between the NCC and the polymer matrix.