Time‐dependent changes in morphology of neat and reinforced epoxy resins part I. Neat epoxies

Jovan Mijovic; King‐Fu ‐F Lin

doi:10.1002/app.1986.070320125

Time‐dependent changes in morphology of neat and reinforced epoxy resins part I. Neat epoxies

Jovan Mijovic, King‐Fu ‐F Lin

Chemical and Biomolecular Engineering

Research output: Contribution to journal › Article › peer-review

Abstract

An investigation was conducted of the morphological changes in neat epoxy resins after cure, that is, during cooling and subsequent “annealing” at a temperature below the glass transition. A series of bifunctional and tetrafunctional epoxy formulations were prepared and studied. A simultaneous drive toward thermodynamic equilibrium (homogeneity) and morphological inhomogeneity was found to take place in the glassy network. A conceptual model was advanced to explain the time‐dependent development of inhomogeneous morphology in the glassy state. After a certain sub‐T_g annealing time, “morphological equilibrium” is reached while physical aging of the glassy network (decrease in enthalpy and/or free volume) continues to occur. The proposed model, based upon the variation of contractive forces throughout the epoxy network, was corroborated by experimental evidence obtained from calorimetric and viscoelastic measurements and electron microscopy.

Original language	English (US)
Pages (from-to)	3211-3227
Number of pages	17
Journal	Journal of Applied Polymer Science
Volume	32
Issue number	1
DOIs	https://doi.org/10.1002/app.1986.070320125
State	Published - Jul 1986

ASJC Scopus subject areas

General Chemistry
Surfaces, Coatings and Films
Polymers and Plastics
Materials Chemistry

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abstract = "An investigation was conducted of the morphological changes in neat epoxy resins after cure, that is, during cooling and subsequent “annealing” at a temperature below the glass transition. A series of bifunctional and tetrafunctional epoxy formulations were prepared and studied. A simultaneous drive toward thermodynamic equilibrium (homogeneity) and morphological inhomogeneity was found to take place in the glassy network. A conceptual model was advanced to explain the time‐dependent development of inhomogeneous morphology in the glassy state. After a certain sub‐Tg annealing time, “morphological equilibrium” is reached while physical aging of the glassy network (decrease in enthalpy and/or free volume) continues to occur. The proposed model, based upon the variation of contractive forces throughout the epoxy network, was corroborated by experimental evidence obtained from calorimetric and viscoelastic measurements and electron microscopy.",

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Time‐dependent changes in morphology of neat and reinforced epoxy resins part I. Neat epoxies

Abstract

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