1. THE LIQUID RESINOUS, SUBSTANTIALLY ISOCYANATE-TERMINATED REACTION PRODUCT OF (I) A HALOGEN CONTAINING POLYHYDRIC ALCOHOL SELECTED FROM THE GROUP CONSISTING OF (A) THE REACTION PRODUCT OF HEXAHALOCYCLOPENTADIENE WHEREIN THE HALOGEN IS SELECTED FROM THE GROUP CONSISTING OF CHLORINE, BROMINE, FLUORINE AND MIXTURES THEREOF, AND A DIHYDRIC ALCOHOL CONTAINING ALIPHATIC CARBON-TO-CARBON UNSATURATION AND (B) THE REACTION PRODUCT OF DECACHLOROOCTAHYDRO -1,3,4-METHENO-2H-CYCLOBUTA (CD)-PENTALENE-2ONE AND A POLYHYDRIC ALCOHOL CONTAINING AT LEAST THREE HYDROXY GROUPS, AND (II) AN ORGANIC POLYISOCYANATE.