MDI异构体对聚氨酯弹性体微观结构和性能的影响

The Effects of MDI Isomer on the Micro-Structure and Property of Polyurethane Elastomer

以聚氧化丙烯二醇(DL-2000)为软段,不同2,4′-异构体含量的二苯基甲烷二异氰酸酯(MDI)和1,4-丁二醇(BDO)为硬段,采用预聚法合成了不同异构体含量的MDI型聚氨酯弹性体。采用FT-IR、DSC和DMA等分析手段对其结构和性能进行了表征。结果表明,随着2,4′-MDI异构体含量的增加,硬段间的氢键结合化程度降低,硬段区聚集结晶的能力也不断下降,硬段趋于均匀分散在连续相软段区中,两相相容性增加,聚氨酯弹性体的T和tanδ大幅度提高。

The different isomer content polyurethanes were synthesized from methylenebis （phenyl isoeyanate） （MDI） of different content of 2,4＇-MDI isomer and butanediol（BDO） as a hard segmont and low molecular weight polyether-diol（DL-2000） as a soft segment by pre-polymerization process . The structure and properties of these polyurethanes were investigated by FTIR, differential scanning calorimetry （DSC） and dynamic mechanical analysis （DMA） respectively. The experiment results indicated that the degree of hydrogen bonding and crystallinity within hard segment were decreased with increasing the content of 2,4＇-MDI isomer. This promoted the phase mixing between hard segments and soft segments and subsequently improved the Tg and tanδ of the PU dramatically.