Preparation And Properties Of Benzoxazine Based On2-allyl Phenol/1,6-hexamethylenediamine

To obtain high performance polybenzoxazine, three benzoxazine (oAP-hda, oC-hda, andP-hda) were synthesized from1,6-hexamethylenediamine, formaldehyde, and three phenols(o-allylphenol, o-cresol, and phenol) via solution method. The chemical structure of oAP-hdawas confirmed by Fourier transform infrared (FTIR) spectroscopy,1H and13C nuclearmagnetic resonance (NMR) spectroscopy, and elemental analysis.The structure changes of oAP-hda in the polymerization were investigated by FTIR andsolid-state13C NMR. The FTIR results show that the absorption intensities of CH2, C–N–Cand C–O–C of the oxazine ring decrease gradually and disappear in the polymerization. Thepolymerization behaviors of oAP-hda, oC-hda, and P-hda were investigated by differentialscanning calorimetry (DSC). The results show that only one exothermic peak shows on theDSC curve of oAP-hda, meaning the temperature of oxazine ring-opening polymerization isclose to the temperature of the radical addition reaction of the allyl double bond. The peaktemperatures of oAP-hda, oC-hda and P-hda are248,237, and254°C, and the exothermicreaction enthalpies are151,182, and185J/g, respectively. The mechanical properties ofPoAP-hda, PoC-hda and PP-hda were investigated by dynamic mechanical analysis (DMA).The results show that glass transition temperatures of PoAP-hda, PoC-hda and PP-hda are87,128, and120°C, and the storage moduli at25°C are1.44,1.86, and1.82GPa,respectively. The thermal stabilities of PoAP-hda, PoC-hda, and PP-hda were investigatedby thermal gravimetric analysis (TGA). The results show that the5%weight losstemperatures of PoAP-hda, PoC-hda, and PP-hda are239,249, and262°C, and their charyield are22%,26%, and18%at800°C in nitrogen, respectively.In an argon atmosphere, the hydroboration and isomerization of oAP-hda were performed,and a borane-containing benzoxazine (oPB-hda) and a propenyl-containing benzoxazine(oPP-hda) were obtained. The chemical structures of oPB-hda and oPP-hda were confirmedby1H NMR and13C NMR. The polymerization behaviors of oPB-hda and oPP-hda were studied by DSC. The results show that the peak temperatures of oPB-hda and oPP-hda are238and217°C, respectively, both lower than that of oAP-hda. The mechanical properties ofPoPB-hda and PoPP-hda were studied by DMA. The storage moduli of PoPB-hda at roomtemperature is1.06GPa and the glass transition temperature is75°C, and both lower than thatof PoAP-hda, whereas the storage moduli of PoPP-hda at room temperature is2.08GPa andthe glass transition temperature is92°C, and both higher than that of PoAP-hda. The thermalstabilities of PoPB-hda and PoPP-hda were studied by TGA, and the results show that theweight loss temperatures and char yields of PoPB-hda and PoPP-hda were higher than that ofPoAP-hda.An o-allylphenol based epoxy resin (oAP-EP) was synthesized from o-allylphenol,formaldehyde, and epichlorohydrin. The oAP-hda was blended with oAP-EP in different massratio, followed by thermally polymerization of the blends. The polymerization behaviors ofoAP-hda/oAP-EP were studied by DSC, and the dynamic mechanical properties and thermalstabilities of the corresponding polymers were studied by DMA and TGA. With the rising ofoAP-EP content, the peak temerature of the DSC curve of oAP-hda/oAP-EP decreasesgradually, the reaction heat enthalpy reduces, the storage moduli of the copolymers increases,the glass transition temperature decreases, the initial decomposition temperature slightlyenhances, and the char yields at800°C decrease.