Organomontmorillonite/graphene-PLA/PCL nanofilled blends: New strategy to enhance the functional properties of PLA/PCL blend

The aim of this work is to study the effect of combining organomontmorillonites (Cloisiteel (R) 5A and Cloisite (R) 30B) with epoxy functionalized graphene on the morphology and different properties of a polylactic acid (PLA)/poly(epsilon-caprolactone) (PCL) blend. To this end, rheological, morphological, barrier and thermal properties were evaluated. The use of nanofiller mixtures caused significant enhancements in terms of storage and loss modulus of a PLA/PCL matrix, indicating a high degree of co-reinforcement in comparison to that observed when the nanofillers were filled separately. The results from transmission electron microscopy and the non-dependency of the storage modulus in the low frequencies showed that both graphene sheets and clay mineral layers resulted in a fine dispersion and better exfoliation in the PLA/PCL blend matrix. The compatibility of the biodegradable PLA/PCL blend was improved in the presence of organoclays and organoclay/graphene mixtures. PLA/PCL nanofilled blends exhibited higher barrier properties than the pure blend and interesting values were obtained by adding hybrids of organomontmorillonite and graphene, which were linked to their degree of intercalation and also to the existence of synergy between these nanofillers. Melt blending of PLA/PCL and all different nanofillers induced significant improvements of thermal stability. The use of filler mixtures to prepare composite materials is a very interesting way to have the best properties using classical methods of preparation. (C) 2017 Elsevier B.V. All rights reserved.