| This work investigates the use of hexagonal boron nitride as a filler for the bisphenol-A/aniline based polybenzoxazine. The combination of these two materials provides a promising composite material system geared towards meeting the increasingly stringent requirements imposed on electronic packaging materials. The boron nitride particles primarily serve to improve the heat dissipation of polymers. In order to serve this purpose effectively, high filler loadings are typically required. The use of high filler loadings, however, increase the importance of the interfacial region between the boron nitride particles and the polymer matrix as the relative ratio of interfacial material to bulk material increases. The use of high filler loadings can also substantially increase viscosity. This research seeks to help understand the hexagonal boron nitride particle/polybenzoxazine interfacial region as well as help reduce resin viscosity by use of reactive diluents.; The surface chemistry of the hexagonal boron nitride particles is examined by use of diffuse reflectance infrared spectroscopy. Surface functional groups are determined to consist of a mixture of primary and secondary amine groups as well as some hydroxyl groups. A chemical surface treatment is also introduced to modify the boron nitride surface chemistry.; The influence of the hexagonal boron nitride particle surface on the polymerization of the benzoxazine monomer is examined by differential scanning calorimetry. By systematically varying the thickness of benzoxazine coatings on boron nitride particles, a distinct influence of the surface substrate on the polymerization reaction is observed. At a coating thickness calculated to be on the order of a monolayer, the heat of reaction is reduced, while the exothermic peak temperature and peak width at half height are increased relative to that of the bulk resin values. The influence of the surface treatment on the viscosity, dynamic mechanical properties, and flexural properties of the filled composite is also investigated.; The melt viscosity reduction of the benzoxazine monomer through use of reactive diluents is also presented. With only 25 mole% reactive diluent, viscosity is reduced to 20% of the neat resin. The reactive diluent composition is systematically varied to examine the trends in the dynamic mechanical properties of the modified polybenzoxazines. |
