Development of polylactic acid (PLA) based blends and their nanocomposites for packaging applications.

摘要

Plastics packaging is one of the worst pollution menaces today. Therefore it is necessary that 'packaging should go green'. Polylactic acid (PLA), renewable resources based biodegradable polyester, is a viable alternative to many fossil-fuel based plastics. However, natural poly-l-lactic acid (PLLA) is a stiff plastic, and thus needs to be made tougher for many packaging applications. Toughening of PLLA can be achieved by blending PLLA with tough polymers. This research consists of two parts: (i) toughening of PLLA through blending with selected tough bio-polymer and (ii) fabrication of nanocomposites from selected blends and a specific organically modified montmorillonite (OMMT) clay to achieve the stiffness-toughness balance. 'Nanocomposite' is one of the best techniques to achieve the required material performances. Extrusion followed by injection molding was adopted in fabricating various samples from blends and nanocomposites. PLLA was melt compounded with several tough biodegradable polymers and a specific tough plastic (poly-(butylene adipate-co-terephthalate), PBAT) was selected for further studies. PLLA-PBAT blends of varying compositions were reinforced with OMMT clay. The blends and nanocomposites were characterized through thermo-physical and mechanical analyses. Environmental scanning electron microscopy (ESEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to study the morphology behaviors. Extrusion followed by compression molding was adopted in fabricating films for barrier property evaluations. Finally, experimental results were correlated with theoretical Halpin-Tsai model using pseudo-inclusion.