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Poly(lactic acid) (PLA) nanocomposite ternary blends based on unmodified sepiolite were prepared by melt blending using a corotating twin-screw extruder. Two grafted polymers were used as compatibilizer agents, in an effort to increase the PLA tensile toughness. The influence of incorporating a low-cost commodity low-density polyethylene, as dispersed phase to the composites on thermal degradation, and rheological and tensile properties was studied. The morphology of the blends and composites was determined through transmission and scanning electron microscopy techniques. Results showed that the compatibilized blends prepared without clay have higher thermal degradation susceptibility and tensile toughness than those prepared with sepiolite and significant changes in complex viscosity and melt elasticity values were observed between them. The nanocomposite blends exhibited similar thermal degradation, lower tensile strength, and Young's modulus values and increased elongation at break and tensile toughness, complex viscosity, and storage modulus compared with those of the nanocomposite of PLA. These results are related to the clay dispersion, to the type of morphology of the different blends, to the localization of the sepiolite in the different phases, the thermomechanical degradation of the PLA matrix phase during melt blending and the grafting degree of the compatibilizers used. POLYM. ENG. SCI., 52:988-

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In this study, the effectiveness of three random copolymers based on blocks of poly(lactic acid) and polyethylene (PLA‐PE) used as compatibilizer in PLA and high density polyethylene blends (PLA/HDPE) was evaluated in terms of thermal and mechanical properties. The compatibilizers were synthesized by different ways: reactive extrusion (C1), ring opening polymerization of lactide with PE with —OH substituent group (PE‐OH) as initiator (C2) and polycondensation of lactic acid in presence of PE grafted with maleic anhydride (PE‐g‐MAH) (C3). The compatibilizers were used in two different proportions (5 and 15 wt%) and their efficiency was compared with a commercial compatibilizer (C0). The blends with C2 compatibilizer exhibited the highest tensile toughness (350% of increment compared with neat PLA/PE) because of the morphology attained. However, it was found that a relationship exists between the improvement of the compatibility and the loss of the thermal stability (−28°C) in PLA/HDPE blends. POLYM. ENG. SCI., 54:522–530, 2014. © 2013 Society of Plastics Engineers

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