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A DSC study of Z 2 −Z 3 viscosity blown soybean oil
Author(s) -
Kenar James A.,
McElligott Joneen,
Hwang HongSik,
Erhan Sevim Z.
Publication year - 2002
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-002-0619-y
Subject(s) - soybean oil , analytical chemistry (journal) , activation energy , kinetic energy , atmospheric temperature range , materials science , reaction rate constant , chemistry , kinetics , thermodynamics , chromatography , organic chemistry , food science , physics , quantum mechanics
The thermal oxidation of four commercially available neat blown soybean oil samples and a heat‐bodied soybean oil sample, obtained from various manufacturers, having Gardner bubble viscosities between Z 2 and Z 3 was investigated using nonisothermal DSC under a constant oxygen flow and a heating rate (β) ranging from 3 to 20°C/min. The extrapolated onset temperatures ( T e1 and T e2 ) and maximum temperature of heat flow ( T p2 ) at different β were determined from the DSC curves and used in conjunction with the Ozawa‐Flynn‐Wall method to estimate the kinetic parameters of oil thermal oxidation. At a β of 10°C/min, the calculated activation energies ( E a ) for the blown soybean oil samples investigated ranged between 57.7 and 74.3 kJ/mol for T e1 , 37.6 and 55.3 kJ/mol for T e2 , and 54.7 and 63.0 kJ/mol for T p2 . For comparison, a Z 2 −Z 3 heat‐bodied soybean oil sample had activation energies of 72.5, 39.8, and 61.9 for T e1 , T e2 , and T p2 , respectively. By 1 H NMR, the amount of allylic and bis‐allylic hydrogens present in the blown soybean oil samples relative to an unmodified soybean oil sample was determined to range from 40.3 to 48.2% and 14.9 to 22.4%, respectively.