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A new approach to estimate the curing mode of thermosetting polymer films with regard to physical aging and slow chemical processes
Author(s) -
Zhavoronok Elena S.,
Senchikhin Ivan N.
Publication year - 2020
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.49373
Subject(s) - thermosetting polymer , curing (chemistry) , epoxy , differential scanning calorimetry , glass transition , materials science , polymer , composite material , thermostat , thermodynamics , physics
We propose an original method to determine the temperature and time required for additional curing of physically aged partially cured glass‐shaped systems, based on the example of epoxy amine systems. The approach consists of the plotting of temperature–time–transformation (TTT) diagrams, supplemented with lines, which illustrate the shift in glass transition temperature ( T g ) as a result of the processes of physical aging (enthalpy relaxation) and with isoconversion curves. Then we should determine T g of partially cured and aged sample at a certain temperature. Having known this T g value, the position of the isoconversion curve at a given point and T g,∞ as well, we can determine the postcuring time at T = T g ,∞ + 5 K. Thus, the method provides information about the temperatures and the duration of these two consecutive steps. The TTT diagrams are based on experimental results obtained by differential scanning calorimetry in dynamic mode with preliminary heated samples in an external thermostat. The proposed approach based on epoxy amine systems allows the prediction of the optimal curing mode for thermosetting systems to provide the highest degree of cure. Our method is applicable to a wide range of thermosetting polymer systems that complete transition to a glassy state before full conversion is achieved.