Ternary melt blend based on poly (lactic acid)/chitosan and cloisite 30B A study of microstructural, thermo-mechanical and barrier properties
Résumé
In this study, blends were developed based on poly (lactic acid) (PLA) containing chitosan (CHS) extracted in our laboratory and an organically modified montmorillonite (cloisite 30B) at different amounts from 1 to 4 (in wt.-%). Tensile samples were prepared using twin-screw extrusion followed by injection molding, and films were obtained by press compression. The morphological and mechanical results showed a phase segregation and poor adhesion between the polymers. Indeed, the elongation at break and thermal stability had undergone a major decrease when adding chitosan to the PLA matrix. Glass transition temperature (T-g), melt temperature (T-m) and recrystallization temperature (T-c) decreased with the addition of chitosan, whereby an increase in crystallinity indicated a nucleation effect showing the same results as with the addition of cloisite 30B. An interesting effect of cloisite 30B was found when it was incorporated into the PLA/CHS blend especially with respect to a 4 wt.-% of cloisite 30B amount. The loss of elongation at the break was partially compensated and the thermal stability and crystallinity were improved. The water vapor permeability (WVP) and water vapor transmission rate (WVTR) of PLA/chitosan blends were higher than those for the neat PLA. By incorporating the C30B into the PLA/CHS blends, very interesting and good barrier properties were recorded as compared to neat PLA and PLA/CHS composites.