Effects of CS/EC ratio on structure and properties of polyurethane foams prepared from untreated liquefied corn stover with PAPI

Corn stover (CS) was liquefied by using ethylene carbonate (EC) as liquefying solvent and sulfuric acid as a catalyst at 170 °C for 90 min. Polyurethane (PU) foams were prepared from liquefied corn stover (LCS) and polymethylene polyphenylisocyanate (PAPI) by one-shot method at a [NCO]/[OH] ratio of 0.6 in the presence of blowing agent, surfactant and co-catalyst. The effects of CS/EC ratio (w/w) on the structural, mechanical and thermal properties were studied by means of Fourier Transform Infrared Spectroscopy (FT-IR), thermal analysis (TGA/DSC) and universal tensile machine. FT-IR analysis indicated that urethane linkages were formed; free isocyanate groups existed in samples. All samples had a low thermal stability and decomposition occurred in four successive stages. With the increase in CS/EC ratio, tensile strength and Young's modulus first increased and then decreased, and elongation rate at break decreased. Properties of LCS-PU foams can be changed by varying the CS/EC ratio.