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改性苯并噁嗪树脂的研究
Research on the Modified Benzoxazine Resin
【作者】 王琦玲;
【导师】 李玲;
【作者基本信息】 中北大学 , 高分子化学与物理, 2012, 硕士
【摘要】 苯并噁嗪树脂是一种在传统酚醛树脂的基础上发展起来的新型杂环热固性树脂,它继承了酚醛树脂的优良性能如热性能、阻燃性、良好的电性能,同时它还具有固化时无小分子释放、体积近似零收缩等特性。但是随着科技的发展,苯并噁嗪树脂的耐热性显然不能满足其在各个领域发展的需要,故需对其改性以提高耐热性。本文采用悬浮法在80℃的条件下合成了双酚A型苯并噁嗪树脂(BA-a),观察其外在形貌,可见生成的苯并噁嗪树脂呈现淡黄色均一的粒状物;采用红外光谱(FTIR)对其结构进行分析,可明显观察到945cm-1处为苯并噁嗪的特征吸收峰;对苯并噁嗪树脂的溶解性进行了测定,结果表明,它可较好地溶解在一般的有机溶剂中,如丙酮、氯仿等。为了进一步提高苯并噁嗪树脂的耐热性,采用具有优良热性能的钼酚醛(Mo-PF)、RTM型双马来酰亚胺(BMI)、模压型双马来酰亚胺(BMI)分别改性苯并噁嗪树脂,并研究了不同种类和不同含量的改性剂对苯并噁嗪树脂的固化反应和热分解性能的影响。采用平板小刀法测定了改性苯并噁嗪树脂的凝胶特性,结果显示,钼酚醛和模压型双马来酰亚胺能有效地降低改性苯并噁嗪树脂的凝胶时间,并且根据凝胶点计算了各改性苯并噁嗪树脂的表观活化能,结果为钼酚醛改性苯并噁嗪树脂的活化能低于苯并噁嗪树脂,其他改性苯并噁嗪树脂的活化能均高于苯并噁嗪树脂,最后计算得到了各改性苯并噁嗪树脂的温度—时间关系式和关系图。采用非等温差示扫描量热法(DSC)对改性苯并噁嗪树脂的固化动力学进行了研究。通过Kissinger方程、Ozawa方程和Crane方程,计算得到了改性苯并噁嗪树脂固化反应动力学三因子,结果表明,钼酚醛和RTM型双马来酰亚胺(含量为20%)改性苯并噁嗪树脂的活化能小于苯并噁嗪树脂,其他改性苯并噁嗪树脂的活化能均大于苯并噁嗪树脂。改性苯并噁嗪树脂均为1级反应,同时根据Tβ曲线外推法得到了各自的固化工艺参数。在非等温的情况下采用热重分析法(TGA)对改性苯并噁嗪树脂在氮气中的热分解进行了研究。结果表明,各改性苯并噁嗪树脂的残炭率均得到了不同程度的提高,其中模压型双马来酰亚胺含量为30%时,残炭率为38%,较苯并噁嗪树脂提高了35%。改性苯并噁嗪树脂的耐热温度指数均较苯并噁嗪树脂(180.516℃)高,钼酚醛改性苯并噁嗪树脂的耐热温度指数最高为206.486℃。
【Abstract】 Benzoxazine resin is a new kind of heterocycle thermosetting resin, which developed onthe basis of traditional phenolic, and carries on the excellent properties of phenolic, such asthermal properties, flame resistence and electrical performance. At the same time benzoxazinehas no release of small molecules when curing and volume contraction is nearly zero.However, with the development of technilogy, the heat resistance of benzoxazine can notsatisfy the development of various fields, so the benzoxazine needs to be modified to improveits heat resistance.In this paper, a bisphenol-A based benzoxazine (BA-a) which assumed faint yellow andwell-proportioned particulate matter was synthesized at 80℃by the suspension method.945cm-1is the characteristic peak of BA-a by the fourier transform infrared spectroscopy(FTIR). The solubility of BA-a was measured and the experiment result suggests that theBA-a can dissolve well in general organic solvent such as acetone, trichloromethane and soon.In order to improve the heat resistance of BA-a further, Molybd-phenolic (Mo-PF), RTMbismaleimide (BMI) and moulded bismaleimide (BMI) which have excellent thermalproperties were employed to modify BA-a. The effect of different content and kind ofmodifier on the curing characteristics and thermal decomposition characteristics of themodified BA-a were researched.The gelation properties of BA-a and its modified system were measured. It was shownthat Mo-PF and moulded BMI decreased the gel time of the modified system effectively. Theapparent activation energy of every system was calculated based on the gel point. The resultswas following: the activation energy of the resin system modified by Mo-PF was lower thanthat of the pure benzoxazine resin and the activation energy of the other modified BA-a werehigher than that of the pure benzoxazine resin. The temperature-time equation and figure were obtained.The differential scanning caborimetry (DSC) was used to research the curing kinetics ofmodified benzoxazine resin. Kinetic triplet were calculated by Kissinger equation, Ozawaequation and Crane equation. The result shows that the activation energy of the BA-amodified by Mo-PF and RTM BMI (20%) were lower than that of the pure benzoxazine resinand the activation energy of the other modified BA-a were higher than that of the purebenzoxazine resin. The reaction order of modified benzoxazine were 1. At the same time thecuring process parameters were calculated by extrapolating T~βmethod.The thermal decomposition of modified BA-a was researched by thermogravimetricanalysis (TGA) with the non-isothermal model at nitrogen atmosphere. The result shows thatall modified system improved the char yield, thereinto the moulded BMI (content 30%)improved the char yield maximally (38 wt.%) and was 35% higher than pure BA-a resin. Theheat index of the modified system were higher than that of the pure BA-a resin (180.516℃),moreover the heat index of the modified BA-a by Mo-PF (206.486℃) was highest.
【Key words】 Benzoxazine; Synthesis; Heat resistance modification; Curing kinetics; Thermal decomposition behavior;