Simultaneous rheology and cure kinetics dictate thermal post-curing of thermoset composite resins for material extrusion

Thermoset composite structures printed at room temperature using direct ink writing often collapse during thermal post-curing. This behavior suggests that the rheological properties that govern structural stability (i.e., storage modulus and/or yield stress) are sensitive to both temperature and conversion. The rheo-Raman instrument provides a way to directly link rheological properties, temperature, and conversion. Using this technique, we characterized how the yield stress and storage modulus evolve as a function of conversion at different temperatures and filler contents of fumed silica. This data set focuses on a diglycidyl ether of bisphenol A (DGEBA) epoxy resin (Epon 826, Hexion, Ohio, USA) cured with Jeffamine D-230 (Huntsman Corporation, Texas, USA). Three resins with fumed silica (Cabot Corporation, Massachusetts, USA) mass fractions of 0 %, 5 %, and 10 % were cured and observed isothermally at 70 °C and 100 °C. Rheological and Raman data were obtained, analyzed, and then combined to determine how the yield stress and storage modulus evolve with conversion at different temperatures. These results motivated a two-step schedule designed to prevent a reduction in rheological properties during curing while quickly driving the reaction to high conversion. The two-step schedule began at 70 °C then ramped to 100 °C and is also included in this dataset. This data is described in: Romberg, S.K., & Kotula, A.P. (2023) Simultaneous rheology and cure kinetics dictate thermal post-curing of thermoset composite resins, National Institute of Standards and Technology, submitted for publication.