Development of a novel composite film based on polyurethane and defatted Chlorella biomass: Physical and functional characterization

Abstract

Novel composite films made of polyurethane (PU) and defatted Chlorella biomass (DCB) at different mass proportions (10-70 wt%) were prepared using polyethylene glycol (PEG) as a model polyol and hexamethylene diisocyanate (HMDI) as a coupling agent. Increasing DCB content led to a respective increase in tensile strength and elongation at break of the composites in the range of 33.9-116% and 69.6-248%, compared to the neat PU-PEG film. As confirmed by Fourier transform infrared and scanning electron microscopy analysis, such improvement in mechanical properties can be attributed to the establishment of hydrogen bonds and other molecular interactions between isocyanate groups of PEG-HMDI prepolymer and hydroxyl groups of DCB biofiller along with the uniform distribution of the incorporated DCB into the PU-PEG based matrix. DCB incorporation at the highest content of 70% increased both antioxidant activity and bulk hydrophilicity of the composites by more than 69.3 and 85.0%, respectively, compared to the neat PU-PEG.