Preparation And Thermal Properties Of Benzoxazines Based On B Isphenol-S And Methylamine/Monoethanolamine

The6,6’-bisβ-methyl-3,4-dihydro-2H-benzo[e][1,3]oxazinyl) sulfone (BS-m) was synthesized via a solution method from bisphenol-S, methylamine and formaldehyde. The chemical structure of BS-m was characterized with1H and13C nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and elemental analysis. The ring-opening polymerization reaction of BS-m monomer was studied by FTIR and differential scanning calorimetry. With the polymerization reaction proceeding, the intensities of the absorption peaks of CH2, C-O-C, and C-N-C of oxazine ring decreased gradually, and some of these absorption peaks disappeared. The melting process of BS-m overlapped with the beginning of the ring-opening polymerization reaction. The polymerization kinetic parameters were evaluated.Thermal degradation behavior of the corresponding polybenzoxazine (PBS-m) was studied with FTIR, thermogravimetry-mass spectrometry (TG-MS), and differential thermal analysis (DTA). The results show that the aromatic C-S bonds start to crack at approximately300℃and continue to630℃, and the disruption of the Mannich bridge structure takes place between330℃and660℃. The main products in the whole degradation process consist of SO、SO2、CO2and NO2ect. Two weight loss stages are observed in both nitrogen and air, and the char yield at800℃is about54%in nitrogen.In addition, the bisphenol-s/ethanolamine type benzoxazine (BS-MEA) was prepared. The chemical structure of BS-MEA was confirmed. The conversion of the characteristic group in the polymerization process in air was determined, and the polymerization kinetic parameters were determined. The thermal stability of the corresponding polybenzoxazine was determined by TG and DTA. The char yield at800℃is about53.6%in nitrogen.