固化剂用量对苯甲基化木材制得的聚氨酯树脂微相分离的影响

以二价酸酯与乙酸丁酯混合溶剂为液化试剂,将苯甲基化木材溶液化,得到的木材溶液与三羟甲基丙烷与甲苯二异氰酸酯的预聚物反应制备聚氨酯树脂。利用FTIR、SEM、DTA、TG及DSC等测试手段,研究了固化剂用量对聚氨酯树脂的微观结构和热性能的影响。结果表明,由于木材结构的特殊性和复杂性,使木材溶液得到的聚氨酯树脂较传统的聚氨酯热稳定性提高,表现在其软段、硬段的初始分解温度比传统的聚氨酯分别提高了 4℃和 99℃;随着w(固化剂)由 23. 8%增大到 69 .9%,树脂的玻璃化转变温度提高,微相分离程度增大,并出现相转变;且相转变完成后,即w(固化剂) =69. 9%时,涂膜各项性能指标发生明显的改善,其铅笔硬度可达 4H,附着力≥1级。

Effect of Curing Agent Content on Microsphase Seperation of Polyurethane Based on Liquefied Benzylated Wood

Benzylated wood was liquefied using dibasic ester and n-butyl acetate as liquefaction reagent.A series of polyurethane resins were synthesized from benzylated wood solution obtained and the prepolymer of toluene diisocyanate(TDI) and trihydroxymethylpropane.By FTIR,SEM,DTA,TG and DSC,the effects of curing agent content on microphase separation and thermal properties of polyurethane films were investigated.Results showed that polyurethane resins from benzylated wood solution had better thermal properties than conventional ones,and the initial decomposition temperatures of the soft and hard segments are raised by 4 ℃ and 99 ℃ respectively.When the curing agent content was increased from 23.8% to 69.9%,the glass transition temperature was increased and the degree of microphase separation was enhanced.During the process,the phase transition occurred.After phase transition,when the curing agent content was 69.9%,the mechanical properties of polyurethane resins were greatly improved.The pencil hardness reached 4H and adhesiveness was no less than ratingⅠ.