【作者】 张腾；

【导师】 贝逸翎； 鲁在君；

【作者基本信息】 山东大学 ， 高分子化学与物理， 2014， 硕士

【摘要】 苯并噁嗪树脂作为近年来出现的一类新型耐热性树脂,其噁嗪环官能团不仅可以通过一定的化学方法容易地合成,又可以在热或酸碱性催化剂作用下进行开环聚合反应。苯并噁嗪树脂具有一些优良的特性,如热稳定性,低吸水性,耐化学药品性、分子设计灵活性。因其固化过程无小分子释放、固化工艺简单、体积收缩率小,有优良的耐热阻燃性及机械性能和较高的玻璃化转变温度而受到广泛关注,并应用于许多重要领域。但是,苯并噁嗪树脂固化温度偏高、固化产物交联密度偏低、性脆等缺陷制约了其在一些特殊领域的应用。为了拓展其在高性能材料领域的应用,对聚苯并恶嗪进行改性,制备综合性能优良的材料,是研究聚苯并恶嗪的一个重要方向。其中制备聚苯并恶嗪纳米复合材料,是研究改性聚苯并恶嗪的一个重要分支。本论文将噁嗪环修饰的Fe304@SiO2磁性纳米粒子(Fe3O4@SiO2@BZS)与聚苯并噁嗪进行复合,制备了Fe3O4/聚苯并噁嗪磁性纳米复合材料。首先,采用溶剂热法合成了分散性良好的Fe3O4磁性纳米粒子；其次,利用溶胶凝胶法,在Fe3O4磁性纳米粒子表面包覆一层致密的SiO2,以增强纳米粒子的耐氧化性,制备出Fe3O4@SiO2磁性纳米粒子；再次通过溶胶凝胶法在Fe3O4@SiO2磁性纳米粒子的表面包覆一层含噁嗪环的硅烷偶联剂(BZS),制备出一种新型的Fe3O4@SiO2@BZS磁性纳米粒子。然后,通过一定的方法,将Fe3O4@SiO2@BZS磁性纳米粒子,均匀的分散到苯并恶嗪单体中,高温固化,制备了Fe3O4/聚苯并噁嗪磁性纳米复合材料,并对复合材料的力学性能、耐热性能以及磁性能进行了研究。制备的Fe3O4@SiO2@BZS磁性纳米粒子,粒径尺寸在200-300nm之间；且分散性比较好；外层包覆的有机物的厚度约为10nm,其中有机物的质量占总质量的约4.2%；具有良好的耐热性,在氮气氛围中,700℃的重量残留率为89.6%；虽包覆了两层物质,但仍具有良好的磁性能,饱和磁化强度达到28.7emu/g。对复合材料进行拉伸性能测试,结果表明,当复合材料中Fe3O4@SiO2BZS磁性纳米粒子的含量为3%时,复合材料的力学性能最好,拉伸强度为64.9MPa,相比未改性的聚苯并噁嗪,提高了39.9%；断裂伸长率为2.20%,相比未改性的聚苯并噁嗪,提高了70.1%；但是,当复合材料中Fe3O4@SiO2@BZS磁性纳米粒子的含量为4%时,由于磁性纳米粒子过多,在聚苯并恶嗪中分布不均匀,发生团聚现象,造成复合材料出现缺陷,引起复合材料的力学性能开始下降,拉伸强度降为48.5MPa,断裂伸长率降为1.12%。对复合材料进行热重分析,结果表明,Fe3O4@SiO2@BZS磁性纳米粒子的加入可以提高复合材料的耐热性,复合材料的5%热失重温度、10%热失重温度、800℃时重量残留率相比未改性的聚苯并噁嗪均有所提高。当复合材料中磁性纳米粒子的含量为4%时,复合材料的5%热失重温度、10%热失重温度分别为335℃、360℃,相比未改性的聚苯并嗯嗪分别提高了11℃、13℃；复合材料的800℃时重量残留率为62.5%,与未改性的聚苯并嗯嗪相比,提高了13.8%。对复合材料进行磁性能分析,结果表明,复合材料具有良好的磁性能。更多还原

【Abstract】 Benzoxazine resin as a new class of heat-resistant resin rencently, which is not only can be easily synthesized by certain chemical methods, and ring-opening polymerization reaction can be carried out under heat or catalyst. Benzoxazine resin has some excellent characteristics such as thermal stability, low water absorption, chemical resistance, molecular design flexibility. Benzoxazine resin has simple curing process, small volume shrinkage, no small molecules released in the curing process. Because of excellent heat resistance and flame resistance and mechanical performance, high glass transition temperature, Benzoxazine resin attracted widespread attention, and used in many important areas. However, the high benzoxazine resin curing temperature, low cross-linking density of the cured product, brittle and other defects restrict its application in some special fields. Modified polybenzoxazine is an important research direction to expand its application in the field of high-performance materials. Preparation of nanocomposites is an important aspect of modified polybenzoxazine.In this study, Fe3O4/polybenzoxazine nanocomposites was prepared by uniformly dispersing magnetic nanoparticles (Fe3O4@SiO2@BZS) into the polybenzoxazine matrix. Firstly, well dispersed Fe3O4magnetic nanoparticles was synthesised by solvothermal method. Secondly, Fe3O4magnetic nanoparticles was coated with a layer of dense SiO2by sol-gel method to enhance the oxidation resistance of nanoparticles. Oxazine ring modified Fe3O4@SiO2magnetic nanoparticles (Fe3O4@SiO2@BZS) was prepared by sol-gel method with the hydrolysis reaction of3-(Triethoxysilyl-)n-propyl-3,4-dihydro-2H-1,3-bezoxazine(BZ S). Fe3O4@SiO2@BZS magnetic nanoparticles was dispersed into the benzoxazine monomer, and then cured at high temperature to prepare Fe3O4benzoxazine magnetic nanocomposite. The mechanical properties, heat resistance, and magnetization of nanocomposite were studied.Fe3O4@SiO2@BZS magnetic nanoparticles have good dispersion, and the size of nanoparticles was between200-300nm. Organic coating thickness is about10nm. The proportion of organic mass is about4.2%. Magnetic nanoparticles have good magnetic properties and heat resistance. Magnetization reaches28.7emu/g and the char yield is89.6%at700℃in a nitrogen atmosphere.Tensile properties of composites is studied and the results showed that when the content of the composite Fe3O4@SiO2@BZS magnetic nanoparticles is3%, the mechanical properties of the composites is the best. The tensile strength of64.9MPa Compared to that of the unmodified benzoxazine (46.4MPa), increased by39.9%; elongation at break of2.20%, compared with those of the unmodified polybenzoxazine (1.29%), increased by70.1%. However, when the content of Fe3O4@SiO2@BZS magnetic nanoparticles was4%, the tensile strength and elongation at break decreased. The reason was that agglomeration of excessive magnetic nanoparticles in polybenzoxazine caused defects in nanocomposites. Thermal gravimetric analysis (TGA) showed that Fe3O4@SiO2@BZS magnetic nanoparticles can improve the heat resistance of nanocomposites.5%weight loss temperature,10%weight loss temperature and the weight residue at800℃of nanocomposites, compared with those of unmodified polybenzoxazine, all increased. When the content of the magnetic nanoparticles is4%,5%weight loss temperature (335℃),10%weight loss temperature (360℃), compared with those of unmodified polybenzoxazine, all increased. The weight residue at800℃, compared with that of unmodified polybenzoxazine, increased by13.8%. The results of magnetic analysis showed that nanocomposites have good magnetic properties.更多还原