Properties of biodegradable thermoplastic pea starch/carboxymethyl cellulose and pea starch/microcrystalline cellulose composites

Glycerol-plasticized thermoplastic pea starch (TPS)/carboxymethyl cellulose (CMC) and TPS/microcrystalline cellulose (MC) composites were respectively prepared by a screw extruder. As the reinforcement filler, the effects of CMC and MC contents on the morphology, thermal stability, dynamic mechanical thermal analysis (DMTA), mechanical properties, as well as water vapor permeability (WVP) were investigated. Scanning electron microscope (SEM) showed that there was good adhesion between starch and CMC or MC, but these superfluous cellulose derivatives resulted in the conglomeration in TPS matrix. MC increased the thermal stability, while CMC impaired it. DMTA revealed that the addition of CMC or MC enhanced the storage modulus and the glass transition temperature of the composites. At the low contents of cellulose derivatives (<9 wt%), the greater CMC or MC content were, the more the tensile strength of the composite. The values of WVP decreased with the increasing of cellulose derivatives. TPS/MC composites had better water vapor barrier than TPS/CMC composites.