Investigating the effects of amine-functionalized carbon balls in a polybenzoxazine matrix†
This study contains arithmetical and experimental examinations of the effects of adding carbon nanoballs (CBs) on the curing behavior and material properties of a benzoxazine system. In this article, CBs were synthesized by a solvent method via the condensation of eugenol, ethylenediamine and formaldehyde based on benzoxazine chemistry without the use of templates and surfactants. The CBs were functionalized via amination. The final materials were characterized by different techniques, such as FTIR, Raman, SEM-EDX, XPS and nitrogen adsorption–desorption studies. The experimental results indicated that the materials showed higher surface areas (133.4 m2 g−1). Nanocomposites with amine-functionalized carbon balls (CBs-NH2) were prepared from benzoxazine synthesized from vanillin, stearylamine and formaldehyde through condensation. We evidenced the formation of a polybenzoxazine structure by FTIR and NMR spectroscopy. The curing behavior and material properties of the nanocomposites were studied widely. The DSC thermogram showed an exotherm corresponding to ring opening polymerization. Furthermore, by the incorporation of CBs-NH2 in the polybenzoxazine system, the properties of the PBz/CBs-NH2 nanocomposites were improved significantly, as analysed through tensile strength, dynamic mechanical analysis, crosslink density, thermal stability and flame retardancy. The enhancement in the material properties is due to the strong interaction between the CBs-NH2 and PBz, resulting in the formation of well-crosslinked polymer networks. The morphology and fracture surfaces of the nanocomposites were studied by scanning electron microscopy. The thermal and mechanical properties of the nanocomposites (PBz/CBs-NH2) were found to be outstanding compared with those of the neat PBz.