Synthesis and properties of polyurethane networks derived from new soybean oil-based polyol and a bulky blocked polyisocyanate

BACKGROUND: Developing vegetable oil-based polyols for polyurethane manufacturing is becoming highly desirable for both economic and environmental reasons. Most vegetable oils do not bear hydroxyls naturally. The objective of this work was to prepare a new soybean oil-based polyol with high functionality of hydroxyl groups and built-in (preformed) urethane bonds. RESULTS: A facile and improved method was developed for the transformation of epoxidized soybean oil into carbonated soybean oil under ambient pressure of CO2 gas, with tetrabutylammonium bromide/calcium chloride as catalyst/co-catalyst couple. Ring-opening reaction of the carbonated oil with ethanolamine led to the desired polyol. A one-pack polyurethane system was prepared via combination of the polyol and a blocked polyisocyanate. The polyol and final polyurethanes were fully characterized, and their physical, mechanical, viscoelastic and electrical insulating properties were studied. CONCLUSION: The application of this newly developed soybean oil-based polyol for preparation of electroinsulating casting polyurethanes was examined. The prepared soy-based polyurethanes offered excellent thermal and electrical insulating properties. Also, tunable physical and chemical properties for the final polyurethanes were achieved by replacing part of the soybean oil-based polyol with poly(propylene glycol) (M-n = 1000 g mol(-1)). (C) 2008 Society of Chemical Industry