Title: ON THE NEED FOR INCLUSION OF PHYSICAL AGING IN NEXT GENERATION CURE KINETICS MODELS
Authors: Sherry Kiafar, Anoush Poursartip
Abstract: Currently, best practice for cure cycle design of thermoset matrix composite structures includes cure kinetics modelling for an optimal outcome, e.g., a fast cycle that does not exotherm, or an intermediate hold for on/off tool processing. Smarter and more complex cure cycles, as well as newer resin chemistries require better cure kinetics and associated material models. The focus of our work is the inclusion of the impact of physical aging in these material models for improved thermoset cure simulation. Physical aging is the spontaneous attempt of the material at the glassy state to regain the thermodynamic equilibrium state. Physical aging leads to a reduction of thermodynamic properties such as volume, enthalpy, and entropy. In this study, the influence of physical aging on cure reaction kinetics and the heat capacity of the material have been investigated. Temperature Modulated Differential Scanning Calorimetry (TMDSC) experiments were performed on Hexcel 8552 neat resin. Resin samples were partially cured in the DSC, and physical aging was systematically introduced into the system by annealing the samples in the glassy state for varying predetermined aging times. The subsequent TMDSC heating scan results reveal that the glass transition dynamics of the aged material is different than that of the unaged or rejuvenated samples and must be incorporated into next generation material models to properly capture the material behaviour when physical aging occurs.
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Conference: SAMPE 2023
Publication Date: 2023/04/17
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