Mechanical, thermal, and barrier properties of nanocomposites based on poly(butylene succinate)/thermoplastic starch blends containing different types of clay

Nanocomposites based on blends of poly(butylene succinate) (PBS) and thermoplastic cassava starch (TPS) were prepared using a two-roll mill and compression molding, respectively. Two different types of clay, namely sodium montmorillonite (CloisiteNa) and the organo-modified MMT (Cloisite30B) were used. The morphological and mechanical properties of the nanocomposite materials were determined by using XRD technique and a tensile test, respectively. Thermal properties of the composite were also examined by dynamic mechanical thermal analysis and thermal gravimetric techniques. Barrier properties of the nanocomposites were determined using oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) tests. From the results, it was found that by adding 5 pph of the clay, the tensile modulus and the thermal properties of the blend containing high TPS (75 wt %) changed significantly. The effects were also dependent on the type of clay used. The use of Cloisite30B led to a nanocomposite with a higher tensile modulus value, whereas the use of CloisiteNa slightly enhanced the thermal stability of the material. OTR and WVTR values of the blend composites containing high PBS ratio (75 wt %) also decreased when compared to those of the neat PBS/TPS blend. XRD patterns of the nanocomposites suggested some intercalation and exfoliation of the clays in the polymer matrix. The above effects are discussed in the light of different interaction between clays and the polymers. (C) 2013 Wiley Periodicals, Inc.