Tailoring Mechanical Properties of Rigid Polyurethane Foams by Sorbitol and Corn Derived Biopolyol Mixtures

Abstract

Sorbitol arises to be a strong candidate for renewably sourced polyol synthesis. Moreover, processes for extracting sorbitol directly from cellulosic materials are effective, and materials such as agroforestry residues could be used as green sorbitol sources. Rigid polyurethane foams were successfully synthesized by using mixtures of a sorbitol based high functionality polyol and a corn based diol. Microstructure and properties of the rigid polyurethane foams were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, thermal conductivity measurements, compression tests, and dynamic mechanical analysis. Results showed that the cross-linking density of the formed polymer network was directly modified by polyol mixture ratio, and microstructure and properties also changed in consonance. The incorporation of different amounts of a diol with longer chain length between hydroxyl groups allowed fixing the rigidity of the foams, opening the door to the possibility of designing rigid polyurethane foams with tailored properties.