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Spectroscopic determination of copolymer composition in high isocyanate content polymers
Author(s) -
Brown Richard G.,
Glass J. Edward
Publication year - 1988
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/app.1988.070360815
Subject(s) - copolymer , isocyanate , polymer , titration , fourier transform infrared spectroscopy , polymer chemistry , amine gas treating , urea , adduct , chemistry , infrared spectroscopy , reactivity (psychology) , materials science , organic chemistry , chemical engineering , polyurethane , medicine , alternative medicine , pathology , engineering
Copolymer compositions high in aliphatic isocyanate content cannot be determined by typical titration methods due to crosslinking during polymer workup. A quantitative method involving ultraviolet analysis of an isocyanate/absorbing amine adduct is presented. Agreement between the ultraviolet (UV) method and elemental analysis, in both composition data and reactivity ratios (r 1 r 2 , which are calculated from data obtained by the UV method) delineate a viable method of polymer analysis. Data from Fourier transform infrared (FTIR) analysis of the urea linkage is in good agreement with nitrogen analysis and the UV method, but is sufficiently biased to cause significant differences in r 1 r 2 values. Bias in the infrared analysis may arise from the intra‐ or intermolecular interaction of CO and NH groups of the urea linkage. Hypochromic effects are observed in UV analysis in noncarbonylic solvents. Hypochromicity varied with copolymer composition and could be related to sequence distributions. The hypochromic effects observed were most pronounced in low amine adduct content polymers where the majority of phenyl chromophores are isolated between MMA units.