BIO-BASED POLYURETHANE PREPARED FROM RENEWABLE FEEDSTOCKS
Non-isocyanate polyurethane (NIPU)s were prepared by reacting carbonated soybean oil with kraft lignin using two pot reactions. In the first stage, epoxidized soybean oil (ESBO) reacted with carbon dioxide to form carbonated soybean oil (CSBO) with tetra-butylammonium bromide (TBAB) as the catalyst. In the second stage, urethane monomer was formed from the reaction of CSBO with 3-aminopropyltriethoxylsilane (APES) and was reacted with the kraft lignin. The reaction was catalyzed by lithium chloride and the NIPU was cured both at room temperature and at 70 oC. Effects of lignin composition (20 – 50 wt%) on the NIPU mechanical properties were studied. Fourier transform infrared spectroscopy (FTIR) analysis was used to determine the structure of the lignin, CSBO, and lignin polyurethane. Tensile strength of the NIPU was much more improved when the polymer was cured at elevated temperature compared to when cured at room temperature. On the other hand, room temperature curing favoured high elongation at break.