聚氨酯/酚醛树脂双组份体系泡沫体的制备

采用聚氨酯预聚物(PU)与新型酚醛树脂反应制备了聚氨酯/酚醛泡沫。采用红外光谱对聚氨酯预聚物和酚醛树脂之间的反应程度进行了表征,研究了聚氨酯预聚物与酚醛树脂比例、—NCO含量和二聚体含量对泡沫体制备以及泡沫体性能的影响。结果表明:—NCO基团与酚醛树脂的质量比为40/100时,泡沫体的体积稳定性好,收缩率低;泡沫制备过程中的泛白时间、起泡时间和不粘时间随二聚体含量的增加而延长;泡沫的密度随二聚体含量的增大而增大,而泡沫体积稳定性和吸水率随二聚体含量的增加有下降的趋势;弯曲应力/应变曲线表明,新型聚氨酯/酚醛泡沫的韧性要远远好于纯酚醛泡沫。

Preparation of a polyurethane/phenolic foam from a polyurethane prepolymer

A novel polyurethane/phenolic foam has been prepared by using a polyurethane prepolymer(PU)and a phenolic resin(PF)as the precursors.FT-IR spectroscopy showed that the reaction of PF and PU reached completion.The effect of the ratio of PU to PF,and the amount of the dimer of PU prepolymer present in the mixture on the preparation and properties of the PU/PF foam were studied.The experimental results showed that the foam has good size stability and low shrinkage rate when the mass ratio of -NCO groups to PF resin is 40/100.The content of dimer in the system had a significant influence on the foaming process and foam properties.With increasing content of dimer,the foaming process was characterized by a decrease in cream time,bubble time and tack-free time,and an increase in the density of the resultant foam.The water absorption,volume stability and toughness of the PU/PF foam also showed monotonic changes. In particular,the toughness of the new polyurethane/phenolic foam was much better than that of a pure phenolic foam,as shown by a comparison of the plots of bending stress and strain.