Structure and Thermal Properties of Polyurethane Foams Prepared From Liquefied Corn Stover with PAPI

Abstract

Corn stover (CS) was liquefied by using ethylene carbonate (EC) as liquefying solvent and sulfur acid as catalyst at 170C for 90 min. Polyurethane (PU) foams were prepared by one-shot method through co-polymerization of untreated liquefied corn srover (LCS) with polymethylene polyphenylisocyanate (PAPI) in the presence of blowing agent, co-catalyst and surfactant. The effects of [NCO]/[OH] ratio, ranging from 0.4 to 1.0, on the structure and thermal properties were studied by means of Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). FT-IR analysis indicated the formation of urethane linkages and the occurrence of secondary reactions in co-polymerization. Decomposition of all samples mainly occurred in four successive stages, and with an increase of [NCO]/[OH] ratio, the glass transition temperature (Tg) and the initial decomposition temperature increased and the range of Tg expended, which can be attributed to the increase of crosslink density in LCS-PU foams.