Synthesis and Properties of Non-isocyanate Crystallizable Aliphatic Thermoplastic Polyurethanes

A simple non-isocyanate route synthesizing thermoplastic polyurethanes (TPUs) with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate with 1,4-butanediol and 1,6-hexanediol was conducted at different molar ratios under the catalysis of tetrabutyl titanate. A series of crystallizable non-isocyanate TPUs with high molecular weight were prepared. The TPUs were characterized by gel permeation chromatography, FT-IR, H-1-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, AFM, and tensile tests. The TPUs exhibited M-n ranging from 12 500 to 26 400 g/mol, M-w from 16 700 to 56 400 g/mol, T-m up to 151.4 degrees C, and initial decomposition temperature over 241.8 degrees C. Their tensile strength reached 42.99 MPa with a strain at break of 30.00%. TPUs constructed simply with butylene, hexylene, and urethane linkages were successfully synthesized through a non-isocyanate route.