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Full-Text Articles in Chemistry
Polymer Chain Dynamics In Epoxy Based Composites As Investigated By Broadband Dielectric Spectroscopy, Mohammad K. Hassan, Samuel James Tucker, Ahmed Abukmail, Jeffrey S. Wiggins, Kenneth A. Mauritz
Polymer Chain Dynamics In Epoxy Based Composites As Investigated By Broadband Dielectric Spectroscopy, Mohammad K. Hassan, Samuel James Tucker, Ahmed Abukmail, Jeffrey S. Wiggins, Kenneth A. Mauritz
Faculty Publications
Epoxy networks of the diglycidyl ether of bisphenol A (DGEBA) were prepared using 3,3′- and 4,4′-diaminodiphenyl sulfone isomer crosslinkers. Secondary relaxations and the glass transitions of resultant networks were probed using broadband dielectric spectroscopy (BDS). A sub-Tg γ relaxation peak for both networks shifts to higher frequencies (f) with increasing temperature in Arrhenius fashion, both processes having the same activation energy and being assigned to phenyl ring flipping in DGEBA chains. A β relaxation is assigned to local motions of dipoles that were created during crosslinking reactions. 4,4′-based networks exhibited higher Tg relative to 3,3′-based …
Molecular Scale Cure Rate Dependence Of Thermoset Matrix Polymers, Christopher Harold Childers, Mohammad K. Hassan, Kenneth A. Mauritz, Jeffrey S. Wiggins
Molecular Scale Cure Rate Dependence Of Thermoset Matrix Polymers, Christopher Harold Childers, Mohammad K. Hassan, Kenneth A. Mauritz, Jeffrey S. Wiggins
Faculty Publications
This manuscript demonstrates the molecular scale cure rate dependence of di-functional epoxide based thermoset polymers cured with amines. A series of cure heating ramp rates were used to determine the influence of ramp rate on the glass transition temperature (Tg) and sub-Tg transitions and the average free volume hole size in these systems. The networks were comprised of 3,3′-diaminodiphenyl sulfone (33DDS) and diglycidyl ether of bisphenol F (DGEBF) and were cured at ramp rates ranging from 0.5 to 20 °C/min. Differential scanning calorimetry (DSC) and NIR spectroscopy were used to explore the cure ramp rate dependence of the polymer network …