Research On Synthesis And Application Of Benzoxazines Containing Functional Groups

In order to improve the properties of polybenzoxazines, flexibility of molecular design, one of features of benzoxazine was introduced to design and synthesize benzoxazines with different functional groups. Phenols and amines attached different groups at different position were used as raw materials to produce a series of benzoxazines in this paper. Proton nuclear magnetic resonance (’H NMR), Fourier transform infrared (FTIR) and Elemental Analysis (EA) were used to characterize the benzoxazines with functional groups. The variation of the functional groups in the benzoxazmes during curing was monitored in situ by FTIR. The conversions of the functional groups were calculated according to the Lambert-Bill law. Meanwhile, the benzoxazines were performed on differential scanning calorimeter (DSC) under different heating rate. The apparent activation energies of the benzoxazines during curing were calculated in terms of the empirical Kissinger and Ozawa equations. The gel time of the benzoxazines at different temperature were obtained to be linearly fitted to get the activation energy of gelling in accordance with Arrhenius equation. The results show that the benzoxazines with functional groups were synthesized successfully. The curing activation energy of every benzoxazine calculated by different methods is close to each other. The cure reactions of the benzoxazines were also studied in low-field pulsed nuclear magnetic resonance.The thennal stability of the cured benzoxazines with functional groups was tested in nitrogen by thermogravimetric analysis (TGA). The results show that the temperature at5%mass loss of the cured benzoxazine produced by p-aminophenyl propargyl ether, phenol and paraformaldehyde is the highest value among the cured benzoxazines, it is395℃. The char yield at800℃of the cured benzoxazine produced by p-aminophenyl propargyl ether, p-methoxyl phenol and paraformaldehyde is the highest value, it is64%. The benzoxazines with functional groups were stimulated and modeled by Materials Studio. The results denote that the thennal properties of the cured benzoxazines are influenced by molecular electrostatic energy. The electronic effect of the substituent affects the molecular electrostatic energy. The benzoxazine with propargyl and cyano groups was used to blend with the silicon-containing polyarylacetylene (PSA). Furthennore, the unidirectional carbon fiber (T700CF) was used to reinforce the modified PSA (M-PSA). The flexural property and interlaminar shear strength (ILSS) of the T700CF reinforced M-PSA composites increase.