Abstract: A series of aliphatic anionic waterborne polyurethane nano-dispersions (PUD) with different hard segment content (HSC) were prepared by prepolymer mixing method starting from isophorone diisocyanate (IPDI) and poly(ethylene adipate) glycol. Effects of HSC on the structure and properties of PUD have been studied by FTIR, GPC, DSC and other property tests. The increment in HSC leads to a larger average emulsion particle size, but still below 100 nm，and the size distribution becomes wider. FTIR spectra illustrated that more hydrogen bonded urea groups exist in the polymer structure at higher HSC, and the number average molecular weight has a slightly increase as measured by GPC. According to DSC analyses, the glass transition temperature of hard segment increases while that of soft segment decrease indicating an enhanced phase separation at higher HSC. The tensile strength of resultant film prepared from the PUD has a highest value of 52 MPa at 30% HSC, and the breaking elongation decreases dramatically from 2250% to 864% with the HSC increasing. The water resistance is the best at the highest HSC.

摘要： 以异佛尔酮二异氰酸酯和聚酯多元醇为主要原料，用预聚混合法合成了一系列硬段含量不同的脂肪族阴离子水性聚氨酯纳米乳液。通过FTIR、GPC、DSC等，研究了硬段含量对产品结构和性能的影响。结果表明，随着硬段含量增加，乳液平均粒径逐渐增大但仍小于100 nm，粒径分布逐渐变宽；分子结构中成氢键的脲键增多；数均相对分子量略有增加；DSC分析表明软段玻璃化温度向低温漂移，而硬段玻璃化温度向高温漂移，说明两相微相分离程度增加。硬段含量为30%时胶膜拉伸强度最高达52 MPa，而断裂伸长率随硬段含量增加从2250%急剧减小到863%。耐水性在硬段含量最高时最佳。