Effects of guar gum content on structure and properties of multi-crosslinked polyurethane composite films

Films from multi-crosslinked polyurethane with different contents of guar gum (1-10 wt%) were prepared through a solution-casting method, followed by a thermal treatment or natural light exposure crosslinking procedure. Acrylic terminated prepolymers were prepared by capping the NCO groups of polyurethane prepolymers with pentaerythritol triacrylate. The effect of the guar gum content on the miscibility, morphology and physical properties of the blend films was investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, surface properties and tensile tests. The results reveal that small guar gum content is well embedded in the crosslinked polyurethane network and forms films with good mechanical properties, thermal behavior and hydrophilic properties. These results prove guar gum to be eco-friendly filler for multi-crosslinked polyurethane network. In the case of polyether urethanes, incorporating up to 3 wt% guar gum leads to a slight enhancement of the elongation at break, while for polyester urethanes incorporation up to 3 wt% guar gum slight increases stress at break values. Incorporating guar gum into the polyurethane networks leads to an increase in the hydrophilic nature of the polymer blends and improved surface structure. The properties of guar gum - which can be abundantly found in nature - make it desirable for polymer blends for biomedical applications.