| Abstract: | A dry starch–oil composite was blended with each of three glycols; ethylene, polyethylene, and propylene, and then reacted with isocyanate to produce polyurethane foams. The liquid glycols permitted the dry composite to blend well with the other ingredients in the foam formulations. Infrared spectra confirmed the presence of urethane structures in the composite–glycol foams. Polyethylene glycol provided a slightly less dense foam than the other glycols in the composite–glycol products. Microscopy showed a greater number of larger cells in the composite–polyurethane glycol foams. Infrared spectra indicated essentially no qualitative differences in the composite–glycol foams with the three glycols. By prestaining starch with toluidene blue and oil with sudan red, the location of the starch and oil components of the milled composite were observed in the composite–propylene glycol foam. Intact flakes of the composite were observed in the foam. An apparent loss of mobility of oil in the composite–polyurethane foam, as evidenced by NMR analysis, is probably due to crosslinking by isocyanate diffusing into the flakes. Both the cell structure and uniformity of blending were improved by using these glycols rather than the polyester polyol described previously. J Appl Polym Sci 69: 957–964, 1998. Published 1998 John Wiley & Sons, Inc. |
