介孔二氧化硅的功能化改性及其环氧树脂复合材料的热解与燃烧性能研究

发布时间：2018-03-18 03:29

本文选题：功能化介孔二氧化硅　切入点：环氧树脂　出处：《中国科学技术大学》2015年博士论文　论文类型：学位论文

【摘要】：介孔二氧化硅凭借自身独特的介孔结构,被广泛地应用在分子吸附、催化、复合材料等领域。为了解决介孔中空二氧化硅的合成步骤繁琐且价格昂贵、以及当前阻燃环氧树脂的阻燃效率低和热稳定性下降等问题,本论文提出了一种合成介孔中空二氧化硅的新方法,并且制备了纳米片层及含磷阻燃剂组装改性的介孔二氧化硅以及介孔二氧化硅负载纳米颗粒杂化物,研究环氧树脂/功能化介孔二氧化硅纳米复合材料的热稳定性和阻燃性能,并探讨了可能的阻燃机理。取得的研究进展如下： 1.为了解决目前合成介孔中空二氧化硅存在的价格昂贵、产量低及制备过程复杂等问题,开发了一种超声辅助制备介孔中空二氧化硅的新方法。通过TEM、 SEM和XRD等技术对产物的形貌、组成和结构进行了表征,成功地制备了尺寸不同的的介孔中空二氧化硅。相比于传统的合成方法,超声辅助制备介孔中空二氧化硅可以精确调控中空结构的尺寸并且能够实现大批量生产。研究发现：随着超声处理功率的增加,介孔中空二氧化硅的壳壁厚度减小,功率越高越有利于形成中空结构的介孔二氧化硅。乙醇/水的体积比也是影响介孔空心二氧化硅形成的重要因素,随着体积比的降低介孔空心二氧化硅球体及内部空心结构的尺寸也随之减小。与传统合成介孔空心二氧化硅的方法相比较,超声辅助法明显地减少了成本,并且制备步骤精简,为介孔中空二氧化硅大规模制备提供了新的思路。 2.采用层层组装法制备了m-SiO2@Co-Al LDH杂化物,并利用溶液共混法制备环氧树脂纳米复合材料。TEM和SEM照片可以发现,尺寸均匀的m-SiO2球体被成功地合成,并且随着吸附层数的增加m-SiO2表面变得更加粗糙。XRD、XPS和STEM表征证明,由于静电作用Co-Al LDH纳米片层均匀地分布在m-SiO2表面。TGA研究表明,与纯EP相比,EP/m-SiO2@Co-Al LDH复合材料的残炭率得到了显著的提高。Cone结果表明,EP/m-SiO2@Co-Al LDH纳米复合材料的阻燃性能要优于同含量的其它复合材料。这主要由于m-SiO2和Co-Al LDH之间产生了协同效应。由于m-SiO2具有相互连通的孔道结构,热质传输路径长而曲折,从而限制了热量和挥发性热降解物的扩散。其次,Co-Al LDH能够促进环氧树脂成炭,从而延缓了气体产物的逃逸,达到阻燃的目的。对复合材料进行热导率表征,发现EP/m-SiO2@Co-Al LDH的热导率远低于EP/Co-Al LDH。DP-MS结果表明,EP基体的主要热裂解产物为碳数较多的碎片,而EP/m-SiO2@Co-Al LDH复合材料的裂解产物成分为碳数较少的碎片,这种碳数较少的碎片更容易被催化而发生成炭。对炭渣进行表征,发现：m-SiO2@Co-Al LDH能促进基体形成致密结实的炭层,阻止易燃性气体挥发和氧气扩散,从而达到阻燃的目的。 3.通过自组装法制备了HM-SiO2@Co-Al LDH@graphene杂化物,利用溶液共混法制备2wt%含量的EP/HM-SiO2@Co-Al LDH@graphene复合材料,以HM-SiO2及Co-Al LDH-graphene作为参照,结果发现HM-SiO2@Co-Al LDH@graphene对EP纳米复合材料减毒和阻燃性能具有明显的增强效果,并通过分析纳米复合材料的热降解气相成分和碳残余试图揭示可能的减毒和阻燃机理。XRD、XPS和STEM表征证明,由于静电作用Co-Al LDH和石墨烯纳米片层均匀地分布在介孔二氧化硅表面。SSTF研究表明,与纯EP、EP/HM-SiO2和EP/Co-Al LDH-graphene相比,EP/m-SiO2@Co-Al LDH复合材料表现出最为优异的毒性气体消除性能。一方面介孔二氧化硅自身的介孔结构起到了良好的阻隔作用,可以延迟易挥发气体与氧气的交换；此外,Co-Al LDH能够催化环氧树脂成炭。锥形量热仪结果表明,EP/HM-SiO2@Co-Al LDH@graphene纳米复合材料的阻燃性能要优于同含量的其它复合材料。 4.利用白组装法制备了HM-SiO2@CS@PCL杂化物,并制备EP/HM-SiO2@CS@PCL纳米复合材料,以HM-SiO2作为参照,结果发现HM-SiO2@CS@PCL对EP纳米复合材料减毒和阻燃性能具有明显的增强效果,并通过分析纳米复合材料的热降解气相成分和碳残余试图揭示可能的减毒和阻燃机理。TEM和SEM照片表明,尺寸均匀的HM-SiO2球体被成功地合成,并且随着组装CS和PCL, HM-SiO2表面及孔道变得更加模糊。TGA研究表明,随着HM-SiO2的添加,EP复合材料的热稳定性提高。与纯EP相比,EP/HM-SiO2@CS@PCL复合材料的残余物得到显著提升且热分解速率下降。一方面介孔二氧化硅自身的介孔结构起到了良好的阻隔作用,可以延迟易挥发气体的逃逸和氧气的扩散；另一方面吸附的CS和PCL可以催化产物成炭。Cone结果表明,HM-SiO2@CS@PCL纳米复合材料的阻燃性能要优于同含量的其它复合材料。这主要由于HM-SiO2、CS和PCL之间产生了协同效应。HM-SiO2具有相互连通的孔道结构并且热导率低。热量和质量在这种孔道结构中传输路径长和曲折,这导致了热量和挥发性热降解物的扩散收到限制。其次,CS和PCL的存在能够促进环氧树脂成炭,从而延缓了气体产物的逃逸,达到阻燃的目的。 5.采用离子吸附法和煅烧法法制备了HM-SiO2/NiCexOy杂化物,并应用于环氧树脂基体中,以HM-SiO2及NiCexOy作为参照,研究了HM-SiO2/NiCexOy对EP纳米复合材料减毒和阻燃性能,并提出了可能的减毒和阻燃机理。TEM和HRTEM结果表明,我们成功地合成了尺寸均一的HM-SiO2/NiCexOy球体,NiCexOy颗粒均匀地分布在介孔中空二氧化硅表面和孔道中。Cone结果表明,EP/HM-SiO2/NiCexOy纳米复合材料的阻燃性能要优于同含量的其它复合材料。SSTF研究表明,随着HM-SiO2或者NiCexOy的添加,EP复合材料燃烧过程中产生的CO浓度和烟密度都相应减小。与纯EP、EP/HM-SiO2和EP/NiCexOy相比,EP/HM-SiO2/NiCexOy复合材料的表现出最为优异的毒性气体消除性能。一方面介孔二氧化硅自身的介孔结构起到了良好的阻隔作用,能够延缓气体产物与氧气的交换。此外,NiCexOy颗粒能够催化环氧树脂成炭。
[Abstract]:Mesoporous silica with its own unique mesoporous structure, is widely used in adsorption, catalysis, composite materials and other fields. In order to solve the problem of hollow mesoporous silica synthesis procedures are complex and expensive, and the current decline in flame retardant epoxy resin flame retardant low efficiency and thermal stability, this paper presents a new method synthesis of hollow mesoporous silica, and nano lamellar and flame retardant assembled modified mesoporous silica nanoparticles and mesoporous silica supported hybrid, research on epoxy resin / thermal stability and flame retardant properties of functionalized mesoporous silica nanocomposites, the flame retardant mechanism was discussed. The following possible research progress:
1. in order to solve the synthesis of hollow mesoporous silica is expensive, the problem of low output and complex preparation process, developed a new method of ultrasonic assisted preparation of hollow mesoporous silica. The morphology of SEM and TEM, XRD and other techniques of product, composition and structure were characterized by the successful preparation of size the preparation of hollow mesoporous silica synthesis. Compared with the traditional method, ultrasonic assisted preparation of hollow mesoporous silica hollow structure can be precisely controlled size and can realize mass production. It was found that with the increase of ultrasonic power, the shell wall thickness of hollow mesoporous silica decreases, more conducive to power the formation of mesoporous silica hollow structure. The volume ratio of ethanol and water is also an important factor affecting the formation of hollow mesoporous silica, with the volume ratio of the lower mesoporous hollow two oxygen Silica spheres and hollow internal structure size decreases. Compared with the traditional method for the synthesis of mesoporous silica hollow, ultrasonic assisted method obviously reduces the cost, and the preparation steps of simplification, for preparing hollow mesoporous silica mass system and a new way of thinking.
2. using m-SiO2@Co-Al LDH hybrid layers of self-assembly were prepared by solution blending and preparation of epoxy resin nano composite material.TEM and SEM photos can be found, uniform sized m-SiO2 spheres were successfully synthesized, and with the increase of m-SiO2 adsorption layer surface becomes more rough.XRD, XPS and STEM indicated that the electrostatic interaction of Co-Al LDH nanosheet is evenly distributed on the surface of m-SiO2.TGA study showed that compared with pure EP, EP/m-SiO2@Co-Al carbon LDH composite rate improved significantly.Cone results show that the flame retardancy of EP/m-SiO2@Co-Al LDH nano composite material to other composite materials with superior content. This is mainly due to the synergistic effect between m-SiO2 and Co-Al LDH. Because m-SiO2 has interconnected pore structure, the heat transfer path is long and tortuous, thus limiting the heat and thermal degradation of the volatile Diffusion. Secondly, Co-Al LDH can promote the epoxy resin into carbon, thus delaying the escape of gas products, flame retardancy of the composite materials are thermal conductivity characterization, EP/m-SiO2@Co-Al LDH found that thermal conductivity was much lower than the EP/Co-Al LDH.DP-MS results showed that the main thermal pyrolysis products of EP matrix for carbon number of debris, and the pyrolysis products composition of EP/m-SiO2@Co-Al LDH composites for carbon less number of pieces, the carbon number of less debris is easier to occur. The catalytic carbon carbon residue were characterized and found that m-SiO2@Co-Al LDH can promote the formation of dense carbon layer of solid matrix, prevent flammable gas volatilization and oxygen diffusion, so as to achieve the purpose of flame retardant.
3. HM-SiO2@Co-Al was prepared by the self-assembly of LDH@graphene hybrids, EP/HM-SiO2@Co-Al LDH@graphene composites prepared by solution blending method, the content of 2wt%, HM-SiO2 and Co-Al LDH-graphene as a reference, the results showed that HM-SiO2@Co-Al attenuated LDH@graphene and flame retardant properties has obvious reinforcing effect of EP nano composite materials, nano composite materials and through the analysis of residual heat drop the gas phase composition and carbon reduction attempts to reveal the possible toxicity and mechanism of flame retardant.XRD, XPS and STEM indicated that the electrostatic interaction of Co-Al LDH and graphene nanosheets distributed uniformly on the surface of mesoporous silica.SSTF study showed that compared with pure EP, EP/HM-SiO2 and EP/Co-Al LDH-graphene, EP/m-SiO2@Co-Al LDH composite showed the most toxicity excellent gas elimination performance. On the one hand the mesoporous structure of mesoporous silica itself plays a good The barrier effect, can delay the exchange of volatile gas and oxygen; in addition, Co-Al LDH can catalyze epoxy resin into charcoal. The cone calorimeter results showed that the flame retardant properties of EP/HM-SiO2@Co-Al LDH@graphene nano composite material to other composite materials is better than the same content.
4. the use of white was fabricated in a HM-SiO2@CS@PCL hybrid, and the preparation of EP/HM-SiO2@CS@PCL nano composite materials, with HM-SiO2 as a reference, the results showed that HM-SiO2@CS@PCL has obvious reinforcing effect on EP nano composite attenuated and flame retardant properties, and through the analysis of nano composite material thermal residual gas phase composition and carbon reduction to reveal possible attenuated and the flame retardant mechanism of.TEM and SEM shows that the uniform size of HM-SiO2 spheres were successfully synthesized, and with the assembly of CS and PCL, HM-SiO2 surface and pores become more fuzzy.TGA research shows that with the addition of HM-SiO2, improve the thermal stability of EP composites. Compared with pure EP, the residue of EP/HM-SiO2@CS@PCL composites improved significantly and the thermal decomposition rate decreased. On the one hand, the mesoporous structure of mesoporous silica itself has played a good role in the barrier, can delay the volatile gas The escape and diffusion of oxygen; on the other hand, the adsorption of CS and PCL can catalyze the resultant carbon.Cone results show that the flame retardant properties of HM-SiO2@CS@PCL nano composite materials to other composite materials with superior content. This is mainly due to HM-SiO2, the synergistic effect of.HM-SiO2 with interconnected pore structure and low thermal conductivity between CS and PCL. Heat and mass in the pore structure in the transmission path long and tortuous, which leads to the diffusion of heat and thermal degradation of volatile is limited. Secondly, CS and PCL could promote the epoxy resin into carbon, thus delaying the escape of gas products, to achieve the purpose of flame retarding.
5. by ion adsorption method and calcination method HM-SiO2/NiCexOy hybrids were prepared and applied to the epoxy resin matrix, using HM-SiO2 and NiCexOy as a reference, the effects of HM-SiO2/NiCexOy on EP nanocomposite attenuated and flame retardant properties, and puts forward the possible mechanism of flame retardant and attenuated.TEM and HRTEM results showed that we successfully the synthesis of uniform HM-SiO2/NiCexOy sphere, NiCexOy particles are uniformly distributed in the hollow mesoporous silica surface and pore.Cone results showed that the flame retardant properties of EP/HM-SiO2/NiCexOy nano composite materials to other composite materials of.SSTF is better than the same content showed that with the addition of HM-SiO2 or NiCexOy, produced in the process of CO concentration and smoke density decreased the combustion of EP composite material. Compared with pure EP, EP/HM-SiO2 and EP/NiCexOy, EP/HM-SiO2/NiCexOy composites exhibited the most excellent toxicity The gas elimination performance. On the one hand the mesoporous structure of mesoporous silica itself plays a good role to delay the barrier, gas exchange and oxygen product. In addition, NiCexOy particles can catalyze epoxy resin into charcoal.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB332;TQ127.2

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