Property Changes of the Waterborne Polyurethane Films Synthesized from Polytetramethylene Ether Glycol and Polycarbonate Diol Due to Hydrolysis

Abstract

Waterborne polyurethanes (WPUs) using polytetramethylene ether glycol (PTMEG) or polycarbonate (PC) diol for polyol component with isophorone diisocyanate and dimethylol butanoic acid were synthesized and the mechanical and morphological properties of the WPU films and of the ones hydrolyzed in an autoclave were analyzed. PTMEG-WPU film showed a lower tensile stress-at-break than that of PC-WPU film. However, the relative stress retention of the former was higher than that of the latter when they were hydrolyzed at 120 o C for the same time. PTMEG-WPU films exhibited irregular surfaces with microparticles before hydrolysis. Many pores were formed in them after hydrolysis, the pore size being increased with increasing hydrolysis time. On the other hand, particle or pore formation was not observed for PC-WPU films both before and after hydrolysis. PU films prepared from N-methyl-2-pyrrolidone solution showed a lower tensile stress and worse hydrolysis behavior compared to the ones obtained from water dispersion.