Preparation and Characterization of Polyurethane Films Using Corn (Zea mays L.) Oil-based Polyol

Abstract

The study focused on the synthesis of polyurethane films utilizing corn (Zea mays L.) oil-based polyol. The activation of hydroxyl sites of the linoleic acid and other fatty acids present in the corn oil was done via epoxidation followed by hydroxylation process. Afterwhich, the activated polyol was reacted with hexamethylene diisocyanate to produce the polyurethane. Variations in the NCO/OH ratio and reaction time were carried to assess the effect on the synthesis of the polymer and its properties. Infrared spectral analyses showed that the polyol conversion was successful due to the presence of epoxy binding sites at 1100 to 1200cm-1 and the hydroxyl groups at 3400 to 3600cm-1. The formation of polyurethane was confirmed in the infrared spectral analyses. The characteristic bonds of urethane groups were observed at 3330cm-1 due to –OH, 2947cm-1 associated to symmetric –CH and 2810cm-1 due to asymmetric stretching vibration of –CH2. The reaction time held no significant change to the composition of the polymer while an increase in NCO/OH ratio entailed rigidity of the film. The 2:1 NCO/OH ratio at three hours reaction showed a balance of desirable mechanical properties and processability. Thermal decomposition characteristics of the polyurethane showed three distinct temperatures as the NCO/OH loading increases to 3 :1 ratio. The maximum tensile strength observed was at 0.285 MPa at 0.45 mm film thickness.