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Effect of reactivity of different types of hydroxyl groups of HTPB on mechanical properties of the cured product
Author(s) -
Panicker Sreelatha S.,
Ninan K. N.
Publication year - 1997
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19970307)63:10<1313::aid-app10>3.0.co;2-5
Subject(s) - reactivity (psychology) , acetic anhydride , acetylation , chemistry , catalysis , polybutadiene , branching (polymer chemistry) , imidazole , polymer chemistry , organic chemistry , medicinal chemistry , copolymer , medicine , biochemistry , polymer , alternative medicine , pathology , gene
The amount of three types of hydroxyl functional groups ( G OH , H OH , and V OH ) in hydroxyl terminated polybutadiene (HTPB), remaining in samples acetylated to the same extent under two different conditions, viz., fast acetylation using acetyl chloride in presence of N ‐methyl imidazole catalyst and slow acetylation by acetic anhydride, differed significantly. For the fast acetylation there is a uniform reduction in all the three types of hydroxyls, probably because the reaction becomes random at rapid rates and the reactivity of the different types of hydroxyls does not play a major role. However, in the slow reaction, the reduction of G ‐type hydroxyls was 30% more than the expected value and there was a corresponding increase in the amount of V ‐type hydroxyls remaining in the acetylated product, showing reactivity of OH in the order of G > H > V . When the reaction is slow, it becomes selective and the change in reactivity of the three types of OH groups is reflected in the extent of conversion. The mechanical properties and the crosslink density data show a reduction in the samples containing lesser amounts of G OH , confirming the branching nature of G OH , which is involved in the crosslinking reaction. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1313–1320, 1997