Direct observation of morphological differences as a function of reaction temperature in model systems for polyurethane foams |
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| Authors: | Dorie J. Yontz Shaw L. Hsu Werner A. Lidy Dana R. Gier Michael H. Mazor |
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| Affiliation: | 1. Polymer Science and Engineering Department, and Materials Research Science and Engineering Center, University of Massachusetts, Amherst, Massachusetts 01003;2. The Dow Chemical Company, Freeport, Texas 77541–3257;3. The Dow Chemical Company, Midland, Michigan 48674 |
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| Abstract: | 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. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 3065–3077, 1998 |
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| Keywords: | polyurethanes AFM atomic force microscopy phase separation crosslinking |
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