Application of linear rheology in determination of nanoclay localization in PLA/EVA/Clay nanocomposites: Correlation with microstructure and thermal properties

A series of single step melt processed PLA/EVA immiscible blends and their organoclay filled nano composites in presence and absence of PTW as a compatibilizer were analyzed in terms of morphological, rheological and thermal properties. Alterations in these properties as a result of change in concentration of each component were correlated with each other. SEM results indicated that morphological response is more sensitive to incorporation of organoclay than compatibilizer presence. TEM and WAXS analyses indicated that simultaneous use of compatibilizer and organoclay in blends changes localization of organoclay and leads to its migration from thermodynamically favored phase towards interface. The selective localization of organoclay and compatibilizer effect on this phenomenon were also investigated by rheological and thermal properties analyses. The rheological properties of the multicomponent systems were investigated using linear viscoelastic measurements with a parallel plate rheometer at small strain amplitudes. By comparing trends of storage modulus of neat blend and its associated compatibilized and uncompatibilized nanocomposites at high and low frequencies and also cross over point between G' and G '' curves, localization of organoclay and effect of compatibilizer on its microstructure could be well explained and correlated with the morphological findings. Moreover it was shown that the linear rheology method is superior over the other implemented experimental methods in precisely tracing microstructural changes in the nanoclay filled multicomponent systems. Finally, using differential scanning calorimetry in non-isothermal mode it was indicated that crystallization of PLA phase may be altered positively or negatively depending on the morphological characteristics, concentration and location of organoclay in the multicomponent system. (C) 2015 Elsevier Ltd. All rights reserved.