Preparation and characterisation of decoloured Novatein and modified PLA blends

Abstract

Modified Poly (lactic acid) (PLA) was blended with Decoloured Novatein® (DNTP), a thermoplastic protein material using reactive extrusion to produce a degradable material with improved properties compared to neat Decoloured Novatein®. PLA was modified through free radical grafting of itaconic anhydride to create reactive side-chain groups. Varying ratios of DNTP/ PLA-g-IA or PLA were prepared. Blending DNTP with PLA was found to increase tensile strength between 22% to 538% and modulus between 201 GPa to 3193 GPa, whereas the strain at break decreased between 80% to 94% depending on the blend ratio. The glass transition temperature of the blends which was measured as the tan δ peak, also revealed an increase when compared to neat DNTP. Scanning electron microscope revealed an enhanced interfacial adhesion between the two phases in the blends with PLA-g-IA suggesting a more homogenous microstructure. WAXS result revealed an insignificant decrease in the crystallinity of the blends compared to neat DNTP, indicating that blending with PLA had no structural effect on DNTP. The results show the possibility and feasibility of blending DNTP with PLA for use in agricultural and packaging applications.