Direct observation of morphological differences as a function of reaction temperature in model systems for polyurethane foams
✍ Scribed by Dorie J. Yontz; Shaw L. Hsu; Werner A. Lidy; Dana R. Gier; Michael H. Mazor
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 577 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0887-6266
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✦ Synopsis
A series of polyurea urethanes was isothermally synthesized from toluene diisocyanate (TDI), water, and trifunctional poly(propylene oxide) in the temperature range of 50 -150°C. Morphologies of the samples vary significantly as a function of reaction temperature. In this system, phase separation competes with polymerization and crosslinking. Both transmission electron microscopy and atomic force microscopy have shown a network type of structure for the 50°C samples, while the 150°C samples appear to be homogeneous. Infrared analysis shows that samples prepared at 150°C possess a morphology that is less strongly hydrogen bonded and has a broader distribution of hydrogen-bonded states compared to those prepared at lower temperatures. From this combination of techniques, it can be inferred that phase separation occurs faster than crosslinking at low temperatures; consequently, a phase-separated morphology forms. In contrast, crosslinking occurs faster than phase separation at higher reaction temperatures.