Thesis Type: Postgraduate
Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Arts and Sciences, Department of Chemistry, Turkey
Approval Date: 2009
Student: TUĞBA EFE
Supervisor: İSMAİL TEOMAN TİNCERAbstract:
A new method for polybenzoxazine synthesis was developed and carried out throughout this work. Bisphenol-A, hexamethylenediamine, and paraformaldehyde were reacted through Mannich condensation reaction forming polybenzoxazine precursors. The reaction was followed by Gel Permeation Chromatography (GPC) as a molecular weight determination method in order to decide the end of reaction. The synthesized product, polybenzoxazine precursors, was polymerized thermally. Polybenzoxazine precursors were also characterized by using spectroscopic methods, 1H-NMR and FTIR, giving an approximation to structural determinations. Thermal characterization of precursors and polybenzoxazine showed that the materials had two exotherms at around 220ºC and 260ºC. The first exothermic peak was an indication of polymerization and preliminary crosslinking reactions while the second peak was due to the final polymerization of polybenzoxazine precursors. These precursors showed no significant structural change in isothermal period of 20 minutes at 200, 220, 225, 235ºC. Mechanical tests were performed on the polybenzoxazine films. The films cured at 180ºC possessed a tensile strength at break 21.04 (±3.56) MPa and an average elongation of 2.7 (±0.93) %. Young’s modulus was calculated as 0.93 (±0.05) GPa for polybenzoxazine films.