Synthesis And Curing Kinetics Of Two Fluorine-based Benzoxazine

Recently, the demand for high performance materials has increased tremendously due to the rapid development of microelectronics and aerospace industries. Benzoxazine, as a new type of phenolic resin, has attracted much attention owing to its outstanding characteristics such as good thermal properties, electrionic properties, and flame retardant.Among the studies of polybenzoxazine, the issue of enhancing the heat resistance and glass transition temperatures （Tg） of polybenzoxazine are highly expected. By taking advantage of the molecular design flexibility of benzoxazine, the high heat resistance and high Tg of polybenzoxazine have been synthesized through altering the functional groups on the amines and/or phenols. In this thesis, we described the synthesis, characterization and cuing kinetics of two kinds of bisphenol fluorene based benzoxazine monomers B-pdf and B-bff, which are obtained from the incorporation of rigid unit and polymerizable group into benzoxazine structure, respectively .The brief contents are shown as follows:Firstly, the fluorine based benzoxazine B-pbf was synthesized from 9, 9-bis（4-hydroxyphenyl） ?uorene and its curing kinetics were investigated by non-isothermal differential scanning calorimetry （DSC） at different heating rates （2, 5, 10 15 and 20 oC/min）. Three different methods （Ozawa, Kissinger and Flynn–Wall–Ozawa） were employed to research the cure kinetics of B-pbf. Ozawa and Kissinger methods showed that the activation energy （E） of B-pdf were 99.0 kJ mol-1 and 95.1 kJ mol-1, respectively. The Flynn–Wall–Ozawa method provided the change of activation energy Ea values as a function of the degree of conversion. The autocatalytic kinetic model was found to be the best description of the investigated curing reactions. The reaction order m and n are 0.95 and 2.03 respectively. Non-isothermal DSC curves obtained from the experimental data showed a good agreement with that theoretically calculated. In addition, the appropriate curing reaction conditions were obtained.Secondly, the polymerizable furan group was introduced into fluorine containing benzoxazine. This novel Benzoxazine bearing fluorene and furan group （B-bff） was prepared using 9, 9-bis（4-hydroxyphenyl） ?uorene, furfurylamine and formaldehyde as raw materials. The chemical structure of B-bff was characterized with FTIR, 1H NMR, ¹³C NMR, and elemental analysis. The curing reaction was also investigated under non-isothermal differential scanning calorimetry （DSC） at different heating rates. The average activation energy of the curing reaction was determined to be 119.1 kJ mol-1 and 121.3 kJ mol-1, respectively, according to Kissinger and Ozawa method. The curing mechanism was given by the Malek methods. The autocatalytic kinetic model was found to be the best description of the investigated curing reactions. In addition, the predicted curves from our kinetic models fit well with the non-isothermal DSC thermograms. Thermogravimetric analysis （TGA） result shows the 5% weight loss temperatures is 402 oC and char yield is 57% at 900 oC. TGA result shows the prepared benzoxazine have the excellent thermal stability.