Premium
Model‐free kinetics: Curing behavior of phenol formaldehyde resins by differential scanning calorimetry
Author(s) -
He Guangbo,
Riedl Bernard,
AïtKadi Abdellatif
Publication year - 2002
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.11378
Subject(s) - thermosetting polymer , curing (chemistry) , differential scanning calorimetry , activation energy , isothermal process , formaldehyde , materials science , thermodynamics , kinetics , kinetic energy , diffusion process , diffusion , polymer chemistry , chemical engineering , chemistry , composite material , organic chemistry , knowledge management , physics , innovation diffusion , quantum mechanics , computer science , engineering
Isoconversional analysis was used to treat nonisothermal DSC data and yield the dependence of activation energy on conversion during the curing process of PF resins. The shape of the dependence revealed that the curing process of PF resins displayed a change in the reaction mechanism from a kinetic to a diffusion regime. In the kinetic regime a comparative DSC experimental analysis between monomer mixtures and PF resins showed that the addition reactions between phenol and formaldehyde had been mostly completed during the synthesis of PF resins and that the main kinetic reactions contained parallel condensations in the curing process. For the diffusion regime a modified equation for the diffusion rate constant, k D = D 0 exp(− E D / RT + K 1 α + K 2 α 2 ), is proposed. This equation is in good agreement with the experimental dependence of E α on α in the diffusion regime, which shows the effect of both temperature and conversion on diffusion. A prediction of the conversion advancement with the reaction time under isothermal condition for PF resin has been made. This prediction can be useful in practical applications for evaluating isothermal behavior of thermosetting systems from nonisothermal experimental data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 433–440, 2003