Preparation and properties of rigid polyurethane foams containing modified cornstarches
| Autor: | M. E. Carr, E. B. Bagley, R. L. Cunningham |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
chemistry.chemical_classification
Yield (engineering) Materials science Polymers and Plastics Extender General Chemistry Surfaces Coatings and Films law.invention chemistry.chemical_compound Compressive strength Polyol chemistry Volume (thermodynamics) law Materials Chemistry Relative humidity Dextrin Composite material Polyurethane |
| Zdroj: | Journal of Applied Polymer Science. 44:1477-1483 |
| ISSN: | 1097-4628 0021-8995 |
| Popis: | Rigid polyurethane foams were prepared containing 20% (based on weight of polyol) unmodfied or modified cornstarches. The cornstarches had been modified by breeding or conversion methods and included waxy, acid-modified waxy, malto-dextrin, and canary dextrin. Due to its more favorable role as an extender, canary dextrin was added to additional foam formulations at 10–40%. Foams containing dextrins responded to compressive stress as control foams with yield points before 10% deformation. Foams filled with the unmodified or waxy cornstarches did not give clearly defined yield points and were measured at 10% deformation. After 14 days under 70°C and ambient conditions, volume increases for the filled foams were 4.0–7.1% vs. 4.6% for the control. The foams filled with canary dextrin increased in volume 4.3%. With the addition of 40% canary dextrin, the volume increases for the foams were 4.4% under thermal conditions and 4.5% under humid conditions (38°C and 98% relative humidity). Under humid conditions for 14 days, the foams containing canary dextrin increased in weight as dextrin content increased (1.5, 3.2, 3.4, and 7.6% with 10, 20, 30, and 40% dextrin, respectively). with 40% canary dextrin in the foams, thermal conductivity was 0.0235 vs. 0.0242 W/mK (0.163 vs. 0.168 Btu in/ft2h°F) for the control. |
| Databáze: | OpenAIRE |
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