EFFECT OF PREPARATION METHOD ON THE RHEOLOGICAL BEHAVIOR OF WATERBORNE POLYURETHANE DISPERSWION

摘要

Two classes of environmentally-friendly polyurethane dispersions have been prepared via prepolymer emulsification process and acetone process. Rheological behavior of these dispersions has been studied as functions of PU-concentration, degree of post-neutralization and temperature. At a critical volume fraction of PU (Φ-0.43), a dramatic increase in the reduced zero shear viscosity was detected for the two dispersions. Co-occurrence of thermal-induced gelation and liquid-liquid phase separation was observed for the prepolymer process, while, only liquid-liquid phase separation was discovered both Theologically and morphologically for the acetone process.