Blends of polylactic acid and arylated soy protein isolate with triacetine as plasticiser

Blends of polylactic acid (PLA) and arylated soy protein isolate (ASPI) were successfully prepared by the extrusion process followed by injection moulding. To improve the interfacial adhesion between PLA and ASPI powder, mandelic acid as an amphiphilic additive was incorporated. Rheological and thermal characterisations of PLA/ASPI blends were performed on rheometer, differential scanning calorimeter and thermogravimetric analyser. Thermomechanical characterisation of PLA/ASPI blends was carried out on a dynamic mechanical analyser. Tensile and flexural modulus of PLA/ASPI blends increased compared to neat PLA. Different amounts (5–15 wt-% wrt PLA/ASPI blends) of plasticiser was added to PLA/ASPI blends containing 2·5 wt-% of ASPI. Results indicated that at 10 wt-% of plasticiser, PLA/ASPI blends showed maximum tensile strength of ∼8·8 MPa as well as appreciable elongation at break. Morphological studies of PLA/ASPI blends at different amounts of plasticiser were also carried out by scanning electron microscope.