Development of high performance PLA based nanocomposites

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The main objective of this research program is to develop biopolymer blends based on Polylactide (PLA) with outstanding properties to replace synthetic polymer blends for engineering and possibly biomedical applications. We will examine the properties of a few promising PLA-based blends made with a bio-based polyamide (PA11) or polycaprolactone (PCL), or with biodegradable poly(butylene succinate adipate), PBSA, and poly(butylene adipate terephthalate), PBAT. In parallel, the addition of nanoparticles to promising blends will be investigated to control and stabilize their morphology and improve their final properties. Potential nanoparticles are cellulose nanocrystals (CNCs), nanoclay (montmorillonite, sepiolite, halloysite nanotubes), carbon nanotubes and graphene. The Hansen solubility parameter differences between various two components of the potential nanocomposites and polymer components will be determined and correlated with the apparent yield stress determined from rheology. These results will be used to make selections of components of most promising nanocomposites. Selective localization of the nanoparticles in the blends will be sought, in particular at the interface of both polymer components. These blends and nanocomposites will be prepared in the molten state via an internal mixer or in solution-cast methods to improve the dispersion of the nanoparticles. Possibly a compatibilizer will be used to reduce the interfacial tension between the polymer components and improve the dispersion of the nanoparticles. Rheometry in shear and elongational flows will be used to verify the stability of the blend and nanocomposite morphology and assess the efficiency of the nanoparticles with or without plasticizers in controlling droplet coalescence. Basic thermo-mechanical, tensile and impact properties of the blend nanocomposites will be determined and compared to those of polypropylene. Eventually, for selected nanocomposites, electrical or barrier properties as well as foamability would be evaluated. Fundamental and original knowledge will be gained on the use of nanoparticles and the effect of their nature and geometry on the control and stabilization of the morphology of blends. The major impact of this work will be to provide key formulations for novel PLA blend nanocomposites with outstanding properties for applications in the automotive and electronic sectors as well as in biomedical fields, sectors of major importance for Canada.