Development of packaging film from bioplastic/clay nanocomposites

Abstract

In this study, polylactic acid (PLA) films were prepared via twin screw extruder attached with blown film die. The research consisted of two parts. The first part concentrates on studying the effect of types and loading of plasticizer, in which they were used to increase the flexibility of PLA, on thermal, mechanical and gas barrier properties of plasticized PLA blown films. From DSC and DMA results, 5 wt% of all plasticizers were compatible with PLA and it affected degree of crystallinity of PLA increased. In addition, tensile tests indicated that polypropylene glycol, PPG(1200) at 5 wt% was a suitable plasticizer for PLA which can be observed from an increase in elongation at break approximately 45 times. The second part focuses on the effect of surfactant types and organoclay loading on properties of PLA/clay nanocomposite blown films. From XRD result, interlayer spacing of organoclay increased compared with that of pristine clay. Furthermore, film of PLA/montmorillonite modified by trimethyl tallow quaternary ammonium chloride (PLA/MMT/M₃T films) showed better clay dispersion and higher transmittance of light than film of PLA/montmorillonite modified by tallow bis(2-hydroxyethyl) amine (PLA/MMT/HT(OH)₂ films). Furthermore, from DSC and DMA results, PLA/MMT/HT(OH)₂ films gave higher degree of crystallinity than PLA/MMT/M₃T films. For mechanical properties, PLA/MMT/M₃T films exhibited higher elongation at break than PLA/MMT/HT(OH)₂ films and 3 wt% of organoclay showed optimum properties when added into with plasticized PLA. In addition, PLA/MMT/HT(OH)₂ films showed higher water vapor permeation (6.19 %) but lower oxygen permeation (7.94 %) compared to PLA/MMT/M₃T films.