1 ,5-萘二异氰酸酯与 1,4-丁二醇基为基质的多嵌段聚氨酯弹性体的合成与性能(英文)

Synthesis and properties of segmented polyurethane elastomers with molecularly uniform hard segments based on 1,5-naphthalene diisocyanate and 1,4-butanediol

利用 1 ,5_萘二异氰酸酯 (NDI)和 1 ,4_丁二醇 (BDO)为均匀硬质分子单体 ,与不同软质分子单体 (聚醚、聚酯、聚硅氧烷 )缩合制备多嵌段聚氨酯弹性体 ,详细研究了硬嵌段相 (NDI)弹性体的结构与性能间的关系 ,发现随着硬嵌段相长度的增加 ,或者氨基甲酸酯中胺基与聚醚、聚酯、聚硅氧烷中软段氧原子间氢键的减弱 ,都导致微相分离程度的增加 ,造成聚合物熔点和熔化热的升高。硬嵌段相熔化的多峰行为是由于形成了NDI/BDO半微晶区 ,在退火时转变为更加有序的结晶微区 ,当温度高于 1 80℃时 ,由于氢键的断裂 ,NDI/BDO硬嵌段发生分解反应 ,该过程源于不很有序的硬嵌段半结晶微区。当温度高于 2 5 0℃时 ,发生快速的分解。在动态力学行为方面 ,NDI基聚醚弹性体比其它硅氧烷基的弹性体展示了更高的硬嵌段区的稳定性 ,同时 ,在使用温度范围内 ,也显示出最高的储能模量值 ,表明刚性对温度的依赖性 。

Segmented polyurethane (PUR) elastomers with different soft segments (polyether, polyester, poly^siloxane) and molecularly uniform hard segments, based on 1,5-naphthalene diisocyanate (NDI) and 1,4-butanediol (BDO), were synthesized. They served as model elastomers for detailed investigations of the structure-properties-relations of the hard segment phase of technologically relevant NDI based elastomers. The amount of microphase separation and with that the melting points and heats of fusion rose with increasing hard segment length and decreasing strength of the hydrogen bonds between the urethane NH groups and the soft segment O atoms in the order polyester, polyether and polysiloxane. Multipeak behaviour at the melting of the hard segments indicated the formation of semi-crystalline NDI/BDO hard domain regions, which transformed into better ordered crystalline domains on annealing. At temperatures above 180℃, decomposition reactions of the NDI/BDO hard segments were initiated by breaking the hydrogen bonds. This process began in the badly ordered areas of the semi-crystalline hard segment domains. Rapid decomposition occurred at temperatures above 250℃. The dynamic mechanical behaviour of the NDI based polyether elastomers showed a higher hard domain stability than elastomers based on other diisocyanates. They showed also in the service temperature range the highest storage modulus value G′ over the broadest temperature range. This indicated a higher and less temperature dependent stiffness as well as a stronger effect as an active filler of the NDI/BDO hard segments.