Browsing by Author "Hamerton, Ian"

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    Developing cure kinetics models for interleaf particle toughened epoxies
    (Society for the Advancement of Material and Process Engineering (SAMPE), 2016-12-31) Kratz, James; Mesogitis, Tassos; Skordos, Alexandros A.; Hamerton, Ian; Partridge, Ivana K.
    In this study, we investigated the cure kinetics behaviour of the commercial Hexply® M21 thermoplastic interleaf epoxy resin system. Dynamic, isothermal, and cure interrupted modulated differential scanning calorimetry (mDSC) tests were used to measure the heat flow of the system, and semi-empirical models were fitted to the data. The cure kinetics model describes the cure rate satisfactorily, under both dynamic heating and isothermal conditions. The glass transition temperature was described using the DiBenedetto equation and showed that heating rate can influence formation of the network; therefore cure schedule must be controlled carefully during processing.
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    ‘Phoenix polymers’: fire induced nanohardness in fibril-forming aromatic cyanate esters
    (Royal Society of Chemistry, 2018-10-25) Mooring, Lyndsey; Thompson, Scott; Hall, Stephen A.; Pani, Silvia; Zioupos, Peter; Swan, Martin; Stone, Corinne; Howlin, Brendan J.; Hamerton, Ian
    For the first time we present nanoindentation analysis of charred, cured aromatic cyanate esters, which exhibit outstanding mechanical properties when analysed under applied loads of 0.1–300 mN. Following charring (900 °C for 10 minutes to achieve graphitised structures), the samples display a remarkable combination of a modulus of elasticity of around 25 GPa and nanohardness of 300 kgf mm−2, making them some 30–40% stiffer than bone and practically as hard as tooth enamel. At the same time we find that under the same conditions the chars are highly resilient, displaying complete elastic recovery with very little plastic deformation. When cured in the presence of copper(II) acetylacetonate (200 ppm) in dodecylphenol (1% w/v active copper suspension) to form a polycyanurate, compound (2) forms a dense, consolidated structure compared with compound (1) under the same conditions. At high magnification, the presence of a nanoscale, fibrillar structure is observed, accounting for the high resilience.