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Keywords:

  • rigid polyurethane foams;
  • soybean oil-based polyol;
  • high viscosity;
  • compressive strength;
  • foaming temperature;
  • thermal conductivity;
  • SEM

Abstract

This study investigated the physical properties of water-blown rigid polyurethane (PU) foams made from VORANOL®490 (petroleum-based polyether polyol) mixed with 0–50% high viscosity (13,000–31,000 cP at 22°C) soy-polyols. The density of these foams decreased as the soy-polyol percentage increased. The compressive strength decreased, decreased and then increased, or remained unchanged and then increased with increasing soy-polyol percentage depending on the viscosity of the soy-polyol. Foams made from high viscosity (21,000–31,000 cP) soy-polyols exhibited similar or superior density-compressive strength properties to the control foam made from 100% VORNAOL® 490. The thermal conductivity of foams containing soy-polyols was slightly higher than the control foam. The maximal foaming temperatures of foams slightly decreased with increasing soy-polyol percentage. Micrographs of foams showed that they had many cells in the shape of sphere or polyhedra. With increasing soy-polyol percentage, the cell size decreased, and the cell number increased. Based on the analysis of isocyanate content and compressive strength of foams, it was concluded that rigid PU foams could be made by replacing 50% petroleum-based polyol with a high viscosity soy-polyol resulting in a 30% reduction in the isocyanate content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013