Preparation and characterization of the agar/polyurethane composites

This study evaluates the properties of the polymer composites obtained by melt blending castor oil-based polyurethane elastomer with agar polysaccharide. Films of the composite were prepared by blending polyurethane resin with agar (0— 12.5 wt%) and were characterized through analysis of their mechanical, dynamic-mechanical, thermal, and morphological properties. The agar filler decreases breaking strains from 450% to 250% and improves tensile strengths from 1.8 to 2.7 MPa depending on the agar content. The intermolecular interactions between polyurethane and agar in composites have been studied by Fourier transform infrared spectroscopy and by mechanical measurements. The water contact angle of the polyurethane—agar composite surface indicated that the presence of agar improves the hydrophilicity of the composite. The morphological observations obtained by optic micrograph show a random dispersion of the agar filler in the polyurethane matrix. Thus, blends of agar with castor oil—polyurethane elastomers can be used to produce composite materials with increased natural raw materials and improved hydrophilicity.