Functional Properties of Biodegradable Nanocomposites from Poly Lactic Acid (PLA)

Abstract

Nanocomposite composed of organoclay(<em><span style="font-family: Times New Roman; font-size: medium;"><span style="font-family: Times New Roman; font-size: medium;">Cloisite 20A-C20A) and Poly lactic acid (PLA) was prepared by solvent casting method. Physical, mechanical, thermal, barrier and microstructure properties of the composite were studied. X-Ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images revealed that the diffraction peak of nanoclay shifted to lower angles and the d-spacing between the C20A layers increased. The formation of an intercalated structure with good compatibility and homogeneously dispersed nanoparticles was observed. Tensile strength (TS) and elastic modulus (E-M) of PLA/C20A nanocomposites increased significantly with clay concentrations, while the values of elongation (E) percentage decreased dramatically. Glass transition temperature (Tg) and degree of crystallinity (</span></span></em><span style="font-family: Symbol; font-size: medium;" lang="ZH-TW"><span style="font-family: Symbol; font-size: medium;" lang="ZH-TW"></span></span><em><span style="font-family: Times New Roman; font-size: medium;"><span style="font-family: Times New Roman; font-size: medium;">%) were determined by DSC (Differential Scanning Calorimetry). The presence of C20A provoked significant raise in both the Tg and the degree of crystallinity. The water vapor permeability (WVP) of the nanocomposites compared to pure PLA moved down by approximately 12-50% by adding 3-7 wt% C20A. An atomic force microscopy (AFM) was applied to evaluate the surface morphology and roughness of PLA films. Pure PLA possessed smoother surfaces and a lower roughness parameter (Sa). New composite based on PLA and C20A could prove to be an improved biopolymer with better functional properties for packaging and other applications.</span></span></em>