Thermoplastic starch foamed composites reinforced with cellulose nanofibers: Thermal and mechanical properties

The present work reports the effect of cellulose nanofibers (CNFs) on the thermal, dynamic mechanical analysis (DMA), density and water uptake of thermoplastic starch (TPS) foamed composites. The obtained thermal and DMA results illustrate that thermal stability, storage modulus (E'), loss modulus (E″) and damping factor (tan δ) increase for all TPS/CNF samples compared to the pure TPS foamed composite. The results showed that the incorporation of CNFs caused an increase in the glass transition temperature (Tg) of the TPS foamed composites. Additionally, thermal results revealed that 1.5 wt% CNF offers superior resistance or stability towards heat compared to its counterparts. Addition of the CNF filler into the TPS matrix decreased the apparent density and water absorption. Interestingly, SEM images illustrate that when a small content of rigid nano particles (1.0 or 1.5 wt%) was added in the foamed composites, the cell size decreased while the cell density increased.