Tunable properties of novel tetra-functional fluorene-based benzoxazines from mixed amines: Synthesis, characterization and curing kinetics

A series of tetra-functional fluorene-based benzoxazines containing both flexible linear aliphatic chain and rigid aromatic structure in their backbones were synthesized using mixed amines such as aniline and n-octylamine, 2,7-dihydroxy-9,9-bis-(4-hydroxyphenyl)fluorene (THPF) and paraformaldehyde as raw materials via Mannich reaction. The prepared benzoxazine monomers were identified by fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (H-1 NMR). In addition, the curing behavior, curing kinetics and rheological properties of these monomers as well as the thermal and mechanical properties of their cured resins were studied using a rheometer, differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), and dynamic thermomechanical analyzer (DMA). The newly developed benzoxazines show good processibility, excellent thermal stability and high glass transition temperature (T-g) values ranging from 291 to 307 degrees C. By varying the proportion of n-octylamine to aniline, the properties of these resins are tuned. (C) 2016 Elsevier B.V. All rights reserved.