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Cooking schedule of alkyd resin preparation. I. Effect of cooking schedule on viscosity‐molecular weight relationship
Author(s) -
Nagata Takumi
Publication year - 1969
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.1969.070131104
Subject(s) - alkyd , viscosity , gel point , materials science , polymer chemistry , chemistry , thermodynamics , organic chemistry , composite material , polymer , physics , coating
The two constants in the equation log η = A + C′ M̄ n 1/2 (η is the viscosity of molten alkyd and M̄ n the number average molecular weight) were determined at 110°C for two kinds of alkyd resin prepared with the same formulation but with different cooking schedules. It was found that the magnitude of the slope C ′ was larger for the alkyd which was prepared by raising the reaction temperature directly up to 230°C, in comparison with that of the alkyd which was prepared by maintaining the temperature at 170°C for an hour and then raising it up to 230°C. Measurements of η and M̄ n were carried out until the gelation occurred. Both upward and downward breaks were observed in log η vs. M̄ n 1/2 plot. Based on these viscometric data, the gel point mechanism was discussed. Disagreements between the molecular weight observed and that calculated from the Flory's theoretical equation became more remarkable as the esterification proceeded. This suggested that a large extent of intraesterification reaction is taking place in alkyd synthesis.