The urethane prepolymer is {HEAD ~ the reaction product} of a dihydroxy functional polyol and {TAIL ~ an isocyanate} 
The urethane prepolymer is { HEAD ~ the reaction product } of a dihydroxy functional polyol and { TAIL ~ an isocyanate }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL