Green polyurethane nanocomposites from soy polyol and bacterial cellulose

With increased environmental concerns, fluctuations in oil prices, and dependency on oil, there has been an emergence in the use of biobased polyurethanes prepared with polyols derived from plant oils, such as soybean oil. In this study, novel polyurethane materials were synthesized using polyols obtained from soybean oils. The polyurethanes were produced by reacting the polyols with polymeric isocyanate with an isocyanate index of 100 at 150 °C for 2 h for complete curing. The mechanical properties of this biobased polyurethane were improved by incorporating novel nanosized cellulose produced from bacteria. The source of the bacterial cellulose nanofibrils was a commercially available food product nata-de-coco. A fine dispersion of the nanocellulose fibrils in biobased polyurethane matrix was achieved by using a high speed homogenizer at 30,000 rpm, which was observed by field emission transmission electron microscopy and scanning probe microscopy. The average diameter size of the cellulose fibers were determined to be 22 ± 5 nm by scanning probe microscopy. The flexural strength and modulus were improved even at 0.125 wt% bacterial cellulose concentration and the optimum nanocomposite was obtained with 0.250 wt% concentration due to good interaction of isocyanates and the cellulose. Dynamic mechanical analysis supported the flexural testing data for modulus values. Transparent thick nanocomposite samples show one additional advantage of the nanocomposite technology.