PLA/PA Bio-Blends: Induced Morphology by Extrusion.

The effect of processing conditions on the final morphology of Poly(Lactic Acid) (PLA) with bio-based Polyamide 10.10 (PA) 70/30 blends is analyzed in this paper. Two types of PLA were used: Commercial (neat PLA) and a rheologically modified PLA (PLA), with higher melt elasticity produced by reactive extrusion. To evaluate the ability of in situ micro-fibrillation (f) of PA phase during blend compounding by twin-screw extrusion, two processing parameters were varied: i) Screw speed rotation (rpm); and ii) take-up velocity, to induce a hot stretching with different Draw Ratios (DR). The potential ability of PA-f in both bio-blends was evaluated by the viscosity () and elasticity () ratios determined from the rheological tests of pristine polymers. When PLA was used, the requirements for PA-f was fulfilled in the shear rate range observed at the extrusion die. Scanning electron microscopy (SEM) observations revealed that, unlike neat PLA, PLA promoted PA-f without hot stretching and the aspect ratio increased as DR increased. For neat PLA-based blends, PA-f was promoted during the hot stretching stage. DMTA analysis revealed that the use of PLA PLA resulted in a better mechanical performance in the rubbery region ( > ) due to the PA-f morphology obtained.