Development and characterization of unmodified kaolinite/EVOH nanocomposites by melt compounding

Abstract

Nanocomposites of unmodified kaolinite (Kaol)/ethylene-vinyl alcohol copolymer (EVOH) with different Kaol contents have been obtained by a two-step process: melt blending in an internal mixer and film processing by co-extruding the obtained clay polymer nanocomposites pellets in between two low-density polyethylene (LDPE) layers. The addition of the clay mineral to the molten polymer has been carried out by using a Kaol/EVOH masterbatch containing 15 mass% Kaol. The so-obtained samples have been analysed by means of WAXS, SEM, TEM, DMA and tensile tests. Finally, barrier properties to water vapour and oxygen at two relative humidities have been assessed. Morphological analysis has revealed high degree of dispersion and distribution of the Kaol within the EVOH matrix. A considerable increase in the mechanical and in the barrier properties has been found. The present work puts forward the effectiveness of an unmodified kaolinite for obtaining ultra-high barrier clay mineral/polymer nanocomposites.