Synthesis of bio-polyurethanes with isosorbide and propanediol based poly(lactic acid) diol

Synthesis of bio-polyurethane (Bio-PU) using isosorbide (ISO) andpoly(lactic acid) (PLA) diols, (propanediol based poly(lactic acid) (PLAP)and PLA esterified with Soybean oil (PLASO)) and pentamethylene (PDI)isocyanate were performed. Crosslinked Bio-PUs were obtained, and the details of the curing kinetics were determined via Fourier transform infrared spectroscopy (FTIR) spectra and differential scanning calorimetry(DSC). Distinct curing behaviors between Bio-PUs with different PLA diol formulations were observed. The addition of PLAP and PLASO increased the curing conversion at approximately 460% higher than Bio-PU without PLA content, as verified by FTIR. The curing peak temperature (Tp)of Bio-PUs with PLAP ranged from 94 to 163°C, while for PLASO Tp was 132-175°C. Bio-PUs based on PLA diols displayed lower activation energy (Ea) during curing as demonstrated using Friedman model, and higher thermal stability as evidenced through thermogravimetric analyses. Reported data offer reliable tools to evaluate the best rote to synthesize biobased polyurethane and manipulate the degree of crosslinking based on composition and processing conditions, allowing product processing to the desired application.