Cure kinetics and synthesis of some resins and prepreg systems
The research reported in this dissertation details the synthesis, characterization and cure kinetics of some resin and prepreg systems. The first chapter gives an introduction to the research presented in this thesis. A summary of epoxy and amine cure reactions that occur in epoxy resins and prepreg systems, the role of catalyst and studies on the cure kinetics with differential scanning calorimetry are presented. The synthesis of various phthalonitrile resins and their cure behavior behavior is also discussed. The second chapter discusses the synthesis of control compounds and physical methods used in later chapters. The third chapter focuses on the cure kinetics of a high performance epoxy prepreg resin system based on DGEBA/TGDDM/DDS using differential scanning calorimetry. Three different sets of experiments were performed in dynamic, isothermal, and combined ramp and soak scanning to follow the cure kinetics in a multi-step cure cycle. The buildup of prepreg resin network structure during the cure cycle has been investigated using Dynamic Mechanical Analysis. Thermal Volatilization Analysis (TVA) and Sub-Ambient Thermal Volatilization Analysis (SATVA) experiments were conducted to fractionalize the condensable products released during curing of the prepreg system. The fourth chapter deals with the cure kinetics of a high performance epoxy prepreg resin system based on TGDDM/DDS with BF3 catalyst with differential scanning calorimentry. As earlier, three different sets of experiments were conducted using dynamic, isothermal and combined ramp and soak scanning to follow the cure kinetics in a multi-step cure cycle. The gel point was measured using dynamic shear rheometry of the prepreg resin in isothermal mode. The fifth nprecursor. The cure profile was investigated on preconditioned resin with muffle furnace under ramp and also combined ramp and soak conditions. The thermal stability of the precured resin was investigated with Thermomechanical analysis. Finally, TVA and SATVA experiments were conducted on uncured resin to characterize volatiles produced during cure.
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