Title: Curing Properties and Post-Cure Characterization of an Epoxy Resin by Encapsulated Sample Rheometry

Authors: Charles Johnson, Unal Yilmazoglu

DOI:

Abstract: Closed cavity rheometry (CCR) was used to characterize the curing kinetics and final properties of a Bisphenol-A (BPA) epoxy resin cured with aliphatic diamine under industrially relevant conditions. Dynamic ramps (1-10 °C/min) established cure onset temperatures increasing from 90.4 °C to 136.3 °C with an apparent activation energy Ea,onset = 44.5 kJ/mol, while isothermal holds (50-70 °C) yielded gel times of 1.9-3.5 hours and Ea,gel = 28.5 kJ/mol, the latter reflecting mechanical percolation at low conversion. A 3² design of experiments (DOE) across ramp rates (2.5-20 °C/min) and cure temperatures (120-140 °C) produced plateau moduli of 2.76-3.51 MPa and tan δ Tg values of 83.9-94.9 °C, with standardized effects below significance thresholds, indicating near-complete cure across conditions. CCR center-point replicates showed excellent repeatability (onset CV = 0.1%, plateau modulus CV 7.5%), and conversion profiles revealed that modulus growth matches enthalpy release during early cure, while CCR Tg exceeded DSC midpoint Tg by 9 °C, consistent with mechanical vs. calorimetric definitions. These results validate CCR as a process-relevant tool for epoxy pot-life estimation, kinetic analysis, and quality control in composite manufacturing.

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Conference: SAMPE 2026

Publication Date: 2026/04/27

SKU: 193

Pages: 17

Price: $34.00