Rigid Polyurethane Foam Prepared from Extruded Starch‐Derived Glycol Glucosides as Chemical Intermediates

Starch‐derived glycol glucosides were prepared by a continuous, twin‐screw extrusion process; reacted with propylene oxide; and evaluated as the polyether polyol (PP) in rigid polyurethane (RPU) foam. Cornstarch with 10% moisture, ethylene glycol (EG), and sulfuric acid as the catalyst were reacted at 160°C in the extruder, using 4 moles EG/mole starch anhydroglucose unit (AGU). After removing unreacted EG from the extrudate by vacuum distillation, the crude mixture of products, which contained at least 85% anomeric glucosides, was reacted with propylene oxide to form the PP with a hydroxyl number of 470. The PP was then deionized and reacted with a polymeric diisocyanate, using a conventional type of formulation and pour‐in‐place procedure. The same formulation and procedure were used to prepare RPU foam from a commercial methyl glucoside PP (hydroxyl number 443) for comparison. The insulating capacity, compressive strength, and dimensional stability properties of the foam with the experimental PP were at least as good as the foam with the commercial PP. This study demonstrates, for the first time, that the starch‐derived glycol glucosides prepared by reactive extrusion processing are suitable chemical intermediates for the preparation of RPU foams with good properties. Also the study suggests that other types of starch‐derived glucosides could be prepared by reactive extrusion processing for potential uses in foams, alkyd resins, surfactants and other products.