Films Based on Poly(lactic acid) Biopolymer: Effect of Clay and Cellulosic Nanoparticles on their Physical, Mechanical and Structural Properties

Physical, mechanical and structural properties of poly(lactic acid) (PLA)-based films containing different amounts of nanoclay and cellulose prepared by solvent casting method were examined. Physical properties including thickness, transparency and color did not change significantly with addition of nanoparticles to the polymer matrix. X-Ray diffraction (XRD) patterns showed that pure PLA has a semi-crystalline structure and addition of nanoclay into this polymer would produce more regular structure which results in improved crystallization. It also showed that the peak is shifted to lower degrees, with greater interlayer distance of nanoclay giving an intercalated structure. Because of the nature and particle size of the MCC, it did not interact sufficiently with the polymer. Tensile strength, elastic modulus and elongation-at-break of neat PLA were 27.44 MPa, 1.84 GPa and 24.53% which with the addition of 7% of nanoclay, was changed to 40.34, 2.62 and 10.36°C, respectively. As the results of XRD, MCC were indications of no significant effect on mechanical properties, AFM images were used to evaluate the surface morphology and roughness of PLA films. Neat PLA had smoother surfaces and a lower roughness parameter (Sa). This study indicates that PLA has acceptable properties which could be used for packaging and other applications.