聚醚型聚氨酯弹性体的合成及其动态力学行为

采用两步合成法,以4,4′-二苯基甲烷二异氰酸酯(MDI)和1,4-丁二醇(BDO)为硬段,相对分子质量分别为1000、2000、4000的聚氧化丙烯二元醇(PPG)为软段,制备了一系列聚醚型聚氨酯(PUR)弹性体,研究了预聚体异氰酸酯指数R及软段相对分子质量对PUR动态力学性能的影响。结果表明,预聚体R值增大,即PUR的硬段含量增加,储能模量G′提高,软段相的玻璃化转变温度(Tg)升高,软硬相区的相容性增大;软段相对分子质量增加,PUR的G′下降,软段相的Tg降低,并出现硬段相的玻璃化转变,软硬相区的相分离程度增大。

SYNTHESIS AND DYNAMIC MECHANICLA BEHAVIOR OF POLYETHER-BASED POLYUREHTANE ELASTOMERS

A series of polyether-based polyurethane ( PUR) elastomers were prepared from 4,4'-diphenylmethanediisocyanate (MDI) and 1,4-butanediol (BDO) as hard segments and polypropylene oxideglycol (PPG) with different relative molecular mass (1000, 2000, 4000) as soft segments by two-step process. The effects of the isocyanate index R of the prepolymer and the relative molecular mass of soft segment on the dynamic mechanical properties of PUR were studied. The results indicated that with the increase of R, the content of hard segments raised, which resulted in notable increases in storage modulus G', glass transition temperature (T_g) of soft segments and compatibility between soft and hard phase domain ; while the increase of relative molecular mass of soft segments led to decrease in G' and T_g of soft segments. In the meantime, the appearance of T_g of hard segments implied high level microphase separation.