Sepiolite as a promising nanoclay for nano-biocomposites based on starch and biodegradable polyester

•Innovative and efficient nano-biocomposites based on starch/polyester blends•Great potential of using the unmodified sepiolite nanoclay as needle-like filler•Significant improvement on dynamic-mechanical and water uptake properties•High interactions between starch and sepiolite nanoclay were observed.

The effects of sepiolite addition (0, 1, 3 and 5 wt%) were evaluated on dynamic-mechanical behaviour, water uptake, thermal and optical properties of thermoplastic starch (TPS)/poly (butylene adipate-co-terephthalate) (PBAT) nano-biocomposites, with different TPS/PBAT (w/w) ratios and nanofiller contents. The results highlighted the improvement of the dynamic-mechanical behaviour with the addition of sepiolite, producing high performance materials. An increase of 25 °C in the Tg of TPS was recorded by DMTA analysis at sepiolite content of 5 wt%. The sepiolite influenced the crystallisation of nano-biocomposites, without causing interference in the crystal organisation, evidenced by DSC analysis. The addition of sepiolite nanoclay decreased the water adsorption rate and water adsorption capacity of the corresponding nano-biocomposites. For such multiphase systems, the successful use of natural sepiolite brought a clear benefit, without the need of any modifications or additional processes to produce advanced nano-biocomposites.