Structure-Mechanical and Thermal Properties Relationship of Novel γ-Valerolactone-Based Polyurethanes

Polymerization of biomass-based diol precursors such as N,N'-1,2-ethanediylbis-(4-hydroxy-pentanamide) and 4-hydroxy-N-(2-hydroxyethyl)-pentanamide with aliphatic (hexamethylene diisocyanate, HDI) and aromatic di-isocyanates (1,4-phenylene-di-isocyanate, PDI and 2,4-toluene-di-isocyanate, TDI) resulted in some novel polyurethanes. The diol precursors were obtained from the ring opening of gamma-valerolactone, GVL, with amine compounds reported as a promising molecular engineering tool to synthesize precursors for new biobased polymers. An interesting investigation about the relationship between structures of the diols and properties such as thermal and mechanical behavior of the obtained polyurethanes was reported in this article. Observation of thermal properties of the polymers showed that the polyurethanes are amorphous and thermally stable until 250 degrees C, with a maximum glass transition temperature of 128 degrees C. The polymer with the highest molecular weight, i.e., 147 kD for the polyurethane made from TDI and 4-hydroxy-N-(2-hydroxyethyl)-pentanamide, showed a high elastic modulus (2,210 MPa), which brings this bio-based system within the window of commercial polyurethane applications.