一种高残炭新型苯并噁嗪树脂的固化及热解动力学

Curing and Pyrolysis Kinetics of a New Benzoxazine Resin with High Char Yield

首先基于Glaser偶合反应制备了一种含共轭二乙炔结构的新型苯并噁嗪单体(CoP-a),然后通过热固化反应得到该单体的聚合物(P(CoP-a))。通过差示扫描量热分析(DSC)和热重分析(TG)对单体的固化反应动力学及聚合物的降解行为进行了研究,采用傅里叶红外光谱(FT-IR)及核磁共振(NMR)对单体结构进行了表征。结果表明,该聚合物在800℃氮气中的残炭率高达75.6%。基于Kissinger法和Ozawa法计算得到,CoP-a的固化反应活化能分别为106.2kJ/mol和108.8kJ/mol,P(CoP-a)的热降解活化能分别为343.4kJ/mol和338.1kJ/mol。该树脂具有良好的反应活性及较高的热稳定性。

A monocyclo-benzoxazine monomer containing alkynyl(P-a)was synthesized and then a new bicycle benzoxazine monomer with conjugated diacetylene structure(CoP-a)was prepared based on the Glaser coupling reaction of the alkynyl group of P-a.The chemical structure of CoP-a was characterized by Fourier Transform Infrared(FT-IR)spectroscopy and Nuclear Magnetic Resonance(NMR).Then,the polymer(P(CoP-a))was obtained by the stepwise thermal curing reaction of CoP-a and the final curing temperature was 200℃.The curing reaction kinetics of CoP-a was analyzed by Differential Scanning Calorimetry(DSC),and the char yield and degradation kinetics of the polymer were investigated by Thermogravimetric analysis(TG).Based on the Kissinger method and the Ozawa method,the curing reaction activation energies of CoP-a and the thermal degradation activation energies of P(CoP-a)were calculated,respectively.The results showed that CoP-a was synthesized successfully,and the oxazine ring was not affected during the Glaser coupling reaction.The initial curing reaction temperature and the reaction peak temperature of CoP-a were 125℃and 222℃,respectively.The char yield of P(CoP-a)was as high as 75.6%at 800℃under nitrogen atmosphere.The curing reaction activation energies of CoP-a calculated by Kissinger method and Ozawa method were 106.2 kJ/mol and 108.8 kJ/mol,and its thermal degradation activation energies of P(CoP-a)were 343.4 kJ/mol and 338.1 kJ/mol,respectively,which were higher than those of many thermosetting resins.The crosslink density of the polymer was increased because of the additional reaction of coupling alkynyl groups,which further increased the thermal stability of the polymer.In summary,this new resin showed good reactivity and high thermal stability,and could be used in the field of ablative materials.