Morphology and Mechanical Properties of Compatibilized Bio-sourced PA/Plasticized Starch Grafted PP Ternary Polymer Blends

Abstract

Morphology and Mechanical Properties of Compatibilized Bio-sourced PA/Plasticized Starch Grafted PP Ternary Polymer BlendsPolymer blends of biosourced polyamide (Rilsan XD) and thermoplastic starch grafted polypropylene (LAB4270) were processed by means of a co-rotating twin-screw extruder, using a solid epoxy resin (D.E.R. 664UE) as a compatibilizer. Morphologies as well as rheological, thermal and mechanical properties of the blends were characterized. The morphology of the reference blend was characterized by nodules of the micron order of magnitude of the dispersed phase (LAB4270) embedded in the polyamide matrix. Even though the morphologies of the blends were not impacted by the addition of the epoxy resin, the mechanical properties as well as the impact resilience were proved to be enhanced. The thermal properties of the blends were as well influenced. A shift of the crystallization temperatures and a decrease of the crystallization enthalpies of both the polypropylene and the PA XD were observed. Thus the addition of the epoxy resin as compatibilizer had proved to be truly effective to obtain a material mostly biosourced with mechanical properties that tend towards combined optimal properties of the different components of the blend.

Contribution of High‐shear Processing to the Compatibilization of (PP/EPR)/PE Ternary Blends

“…Obviously, the same trend is observed for the complex viscosity, as shown in Figure b, the processed blends at 600 rpm highlighted a progressive increase in viscosity at low frequency compared to the other blends. The increase in complex viscosity can be explained by two simultaneous phenomena: the first one is the presence of viscous polymer (PE) and the second one would come from the formation of in situ graft copolymers or crosslinking due to the recombination of ethylene‐based polymers macroradicals occurring from extreme conditions of stress and shear …”

“…On one hand, compared to (PP/EPR)/PE blends processed at 600 rpm, the addition of copolymers induces an increase in complex viscosity at low frequency. The rise of complex viscosity is explained by an increase of the average molecular number () of compatibilized (PP/EPR)/PE/EOC blends (Table ) that can be due to two simultaneous phenomena: (i) the in situ formation of copolymers at the interface (re‐combination of macroradicals) and (ii) EPR/EOC interactions …”