EFFECT OF MONOMER PURITY ON FUNCTIONALITY DISTRIBUTION OF ISRO POLYOL

The functionality distribution of ISRO polyol, a condensation polymer derived from 12-hydroxy stearic acid (THSA) and trimethylol propane (T MP), which is used as a binder in solid propellant has been studied by a dual detector analytical gel permeation chromatographic (DDAGPC) me thod. The results show difference in the amounts of non-, mono-, di- a nd trifunctional molecules present in the samples prepared from commer cial THSA and purified THSA. The difference in functionality distribut ion has been attributed to the presence of monofunctional stearic acid impurity in THSA. Polyol, prepared after removal of the stearic acid impurity, contained more than 50% trifunctional molecules and could be cured with a difunctional curator like toluene diisocyanate (TDI), wh ereas the polyols prepared with commercial THSA were found to contain more than 90% difunctional molecules and no trifunctional ones. These samples needed considerable quantity of trifunctional curator like TMP to get a crosslinked product with TDI. Thus a knowledge of the functi onality distribution is necessary to determine the amount of crosslink er needed to form a good polymer network. (C) 1997 Elsevier Science Lt d.