Identification of volatile products and determination of thermal degradation mechanisms of polybenzoxazine model oligomers by GC–MS

Effect of La2O3 on the thermal stability of polybenzoxazine based on 4,4′-diaminodiphenyl methane

“…The researches indicated that the C-N and C-C bonds in -CH 2 -NR-CH 2 -(Mannich bridge) took place breakage during the thermal degradation of polybenzoxazine, resulting in its primary decomposition [10][11][12][13][14]. Thus we could propose that La 2 O 3 accelerated the cleavage of the C-N and C-C bonds, namely, these bonds was weakened with the addition of La 2 O 3 .…”

“…At 350°C, a band at 3660 cm −1 due to the free phenol hydroxyl and a band at 1190 cm −1 assigned to C-O of phenol hydroxyl were detected, besides, the bands at 1510 and 1610 cm −1 were from benzene ring and the band at 750 cm −1 was assigned to substituted benzene. These observations indicated that the degradation gases as benzene, phenol and their derivatives began to appear, implying that the C-N and C-C bonds in Mannich bridges had broken [10][11][12][13][14] and the possible broken position is shown in Scheme 3b.…”

“…Accordingly, the major degradation gases of BB polybenzoxazine included benzene, phenol, amine and their derivatives between 300 and 550°C, and the alkene was detected with the increase of temperature, which was similar to the kinds of the thermal degradation gases of PC-a and other polybenzoxazines based on aniline or aliphatic amine. However, the appearance of the phenolic gases was earlier than that of the amine gases during the thermal degradation process of BB, just the reverse from those polybenzoxazine, in which the volatilization of the amine compounds was earlier [7,[10][11][12][13][14]. Figure 7 is the FTIR spectra of thermal degradation gases of the BB/La0.5 %.…”

“…The observations showed that the La 2 O 3 accelerated the appearance and volatilization of the phenolic gases. The formation of the phenolic gases primarily resulted from the C-N and C-C bonds cleavage in Mannich bridges [10][11][12][13][14], consequently, the promotion of La 2 O 3 on the appearance and volatilization of the phenolic gases was assigned to the coordination interaction between La 2 O 3 and the nitrogen atoms, which weakened the C-N and C-C For PC-a polybenzoxazine, its aniline structure mostly hung in main chain, as shown in Scheme 3a. The cleavage of C-N and C-C bonds produced aniline and its derivatives during the thermal degradation process of PC-a, and the initial weight loss was mainly from the volatilization of the amine compounds.…”

Thermal degradation of polysiloxane and polyetherester containing benzoxazine moieties in the main chain

“…Studies on thermal decomposition process in the aliphatic amine-based polybenzoxazine model dimers, trimers and tetramers by the evolved gas analysis TGA-GC-MS, also showed that the first stage of weight loss was mainly due to the evaporation of the primary amine. The second stage of weight loss, in contrast, indicated the release of benzene derivatives, phenolic, biphenyl and bisphenol compounds [30][31][32].…”