Microstructure Development and Process Pathway Effects In Glassy Polymer Networks

The ability to track network formation of epoxide/amine polymer matrices in real time through Fourier Transform Infrared Spectroscopy (FT-IR) has resolved the cure path dependency of these glassy material\u27s formation. However, the dependency of epoxy system\u27s morphologies and properties on network formation and cure path remains undetermined, impeding the usage of cure path optimization for improving part performance. In the subsequent work, systems consisting of the difunctional epoxide monomer diglycidyl ether of bisphenol F (DGEBF), the tetra functional epoxide monomer tetraglycidyl 4,4\u27-diaminodiphenylmethane (TGDDM), and a mixture of the two crosslinked with the diamine curing agent 4,4\u27-diaminodiphenylsulphone (44DDS) in stoichiometric and non-stoichiometric epoxide to reactive proton ratios were studied. The network formation of each system was monitored in-situ through near infrared (NIR) FTIR for various cure profiles consisting of isotherms at 120 °C, 150 °C, and 180 °C chosen to elicit altered network formation. Then the relation between network formation and morphologies was studied through atomic force microscopy (AFM), scanning electron microscopy (SEM), and nanoscale IR analysis (AFM-IR). The cure path dependent network formation of each system was determined through NIR analysis indicating an enhanced secondary amine to primary amine reactivity (RS/P) for the systems cured at 150 °C that resulted in a distinct nodular morphology; however, upon post-curing for one hour at 220 °C each system exhibited similar features. This work begins to connect the dependence of epoxy system\u27s properties on cure path through the investigation of morphology development