| 초록 |
Water-borne poly (urethane-urea)s (WBPUs) were prepared by a prepolymer mixing process using aromatic diisocyanate (MDI, 4,4’-diphenylmethane diisocyanate) / aliphatic diisocyanate (H12MDI, 4,4’-methylenebis cyclohexyl isocyanate), polypropylene glycol (PPG, Mn=1000), dimethylol propionic acid (DMPA), and ethylene diamine as a chain extender, and triethylamine as a neutralizing agent. The effect of DMPA content on the chemical structure, dynamic thermo and tensile properties of WBPUs was investigated. The yellowness index (photo-oxidation behavior) change of WBPUs under accelerated weathering exposure was also investigated. As the DMPA content increased, their glass transitions of soft segments (Tgs) were shifted to higher temperature, but hard segments (Tgh) were shifted to lower temperature. The yellowness index of WBPUs containing MDI increased with increasing radiant exposure. But increasing DMPA content, the yellowness index of WBPUs containing MDI decreased. |
