微量水对聚氨酯预聚体结构与溶解性的影响研究

Effects of trace water on the structure and dissolving capacity of polyurethane prepolymer

为了更充分地了解微量水对聚氨酯预聚反应及预聚体结构的影响,用一步法首先合成了聚氨酯初始预聚体,然后研究了微量水及扩链温度等对聚氨酯预聚体的特性粘数、在THF中的溶解性和分子量分布等的影响,采用FT-IR对水扩链预聚体的聚集态结构进行了初步的研究。研究结果表明,水和—NCO基团反应生成聚脲结构,表现在聚氨酯硬段间的氢键作用增强,而硬段与软段间的氢键作用力减弱。微量水的存在可以对聚氨酯预聚体起到扩链作用,但随水量的增加预聚体会生成交联结构,产生不溶性凝胶。聚合温度的提高会加速聚脲结构的形成。

In order to research the effects of the water on structure and polymerization reactive of the polyurethane,the polyurethane preliminary prepolymer was prepared by means of one step firstly.Then the effects of the amounts of water and the extending temperature on the intrinsic viscosity and the molecular weight distribution of polyurethane prepolymer,and dissolving capacity of polyurethane prepolymer in THF were investigated.The aggregation structure of the water expended polyurethane prepolymer was characterized by FT-IR.The results shown that the polyurea structure is generated by —NCO reacting with water because of increasing hydrogen-bond interaction between the hard segments of the polyurethane chains and decreasing hydrogen-bond interaction between the hard segments and soft segments of the polyurethane chains.The polyurethane prepolymer could be extended by trace water.But the crosslinking prepolymer formed with increasing water amount,and the insolubility gels came into being.With increasing temperature the crosslinking reaction accelerated.