首页>
外文期刊>journal of applied polymer science
>Structural investigation of polyurethanes: Infrared spectroscopic investigations of monomeric and polymericN,N′‐diaryl ureas
【24h】
Structural investigation of polyurethanes: Infrared spectroscopic investigations of monomeric and polymericN,N′‐diaryl ureas
展开▼
机译：Structural investigation of polyurethanes: Infrared spectroscopic investigations of monomeric and polymericN,N′‐diaryl ureas
AbstractThe carbonyl stretching vibration of crystallineN,N′‐diaryl ureas at 1640 cm−1undergoes a very considerable shift to 1700 cm−1when these compounds are in solution. This finding is of particular significance in connection with the hard segments of polyurethane elastomers. The absence of a carbonyl band at 1640 cm−1in polyurethane–polyurea systems does not indicate the absence of urea groups or the reaction of urea groups to biuret groups. Urea groups may instead be present in the dissolved, i.e., noncrystalline, form. On the other hand, the absorption at 1640 cm−1is suitable for the determination of crystalliza
展开▼
