纳米粉煤灰增韧酚醛树脂泡沫炭结构和性能的调控机理研究

In this study, nano-coal ash dispersed by ultrasonic and treated with coupling agent was added to fill and modify phenolic resin in the process of polymerization. A kind of phenolic resin modified by nano-coal ash was prepared. After the modified phenolic resin was foamed under pressure (the pore nanometer scale) and then carbonized, coal ash/phenolic resin carbon foam composite with nanometer pore structure was prepared. By the modifition of nano coal ash particle and nano pore structure, the current problems of phenolic resin based carbon foam areas (large pore, poor toughness) can be solved. By the polymerization dynamics, the controlltion on the polymerization of the nano coal ash/phenolic resin composite was studied, the effect mechanism of content, particle size, dispersion, interface bonding of nano coal ash on the structure and properties of phenolic resin also was revealed. By the foaming dynamics, the influence and mechanism of the content, powder dispersion and interfacial kinetics of coal ash on the foaming, curing behavior and pore structure was revealed. By the pyrolysis dynamics, the effects and mechanism of the particle size, dispersion and interfacial of nano ash on the pyrolysis behavior was studied. The micro structure, pore structure and thermodynamic properties of carbon foams modified by nano coal ash was studied, the constitutive relationship between structure and properties was revealed and established. The study master and disclose the relevant scientific principle of controllable design of the carbon foam composite material derived from phenolic resin modified by nano coal ash.The coal ash (waste) was used and the cost of preparation of carbon foam materials was reduced in the study. It provides a new way and theoretical basis for high additional value utilization of coal ash.

本研究拟结合孔径的纳米化和纳米粉煤灰的增韧效应，解决目前酚醛树脂基泡沫炭存在的 (孔径大，韧性差) 难题。在树脂聚合中引入纳米粉煤灰填充改性，采用超声分散和偶联剂处理工艺，原位聚合得纳米粉煤灰均匀分散的改性酚醛树脂。然后液相加压发泡实现孔径的纳米尺度化，最后控制炭化工艺制备得结构及性能可控的粉煤灰/酚醛树脂复合泡沫炭。研究粉煤灰的含量、粒径大小，分散行为及界面结合对酚醛树脂结构和性能的影响及其机理；研究粉煤灰的组成、含量及界面性能对泡孔成核行为和孔结构的影响与调控机制；研究粉煤灰的含量、粒径大小，组成结构及界面性能对碳化行为的影响及其机理；研究纳米粉煤灰对泡沫炭的微观结构，孔结构和性能的影响，掌握和揭示纳米粉煤灰增韧酚醛树脂基泡沫炭的可控设计所涉及的相关科学机理。本项目研究，用粉煤灰代替纳米SiO2/Al2O3，可降低炭材料的制备成本，同时为粉煤灰的高附加值综合利用的新途径提供理论基础。

三维网状孔结构酚醛树脂基泡沫炭是一种新型结构功能材料，具有低密度、高比强度、结构性能可调性和独特的电学、热学、吸波及磁等性能，在高温热防护、过滤器、电容器多孔电极、核防护、电磁屏蔽及吸收材料、燃料电池和催化剂载体等领域具有广阔的应用前景。针对目前酚醛树脂基泡沫炭孔径大和韧性差的难题，本项目采用超声分散和偶联剂处理工艺，原位聚合得纳米粉煤灰改性酚醛树脂，然后液相加压发泡实现孔径的纳米尺度化，最后炭化制备得结构及性能可控的纳米粉煤灰增强增韧酚醛树脂复合泡沫炭。用电子能谱仪、热分析仪、质谱仪、扫描电镜、压汞仪和X-射线衍射仪等研究了改性树脂泡沫体的发泡行为及发泡机理，泡孔结构的影响及其调控机制，研究纳米粉煤灰/酚醛树脂的炭化热解行为，粉煤灰改性对泡沫炭孔结构和微观结构的影响及其规律。用导热仪，材料试验机，热膨胀仪，比热仪等测试分析泡沫炭的热力学性能，揭示纳米粉煤灰对热力学性能的影响规律及机理，阐明纳米孔径和纳米粉煤灰对泡沫炭的协同增强增韧机理。纳米粉煤灰改性酚醛树脂后，引入键能较大的铝氧键、硅氧键，改善了树脂的耐热性能和残炭率。800℃下，5wt.%纳米粉煤灰改性酚醛树脂的残碳率提高10%。通过树脂浓度、发泡压力、固化剂含量和发泡温度等工艺参数的调控实现对孔结构和性能的调控。纳米粉煤灰合理添加量是3-6wt.%，纳米粉煤灰改性不影响树脂的热分解行为和微观结构。改性酚醛树脂泡沫炭，具有分布均匀的纳米孔结构，树脂基体和纳米粒子形成大量的强界面结合，脆性断裂向韧性断裂转化，提高了泡沫炭的韧性和强度。加入少量3wt.% 纳米粉煤灰后，改性泡沫炭的抗压强度增大15%，导热系数减小10 %，冲击强度提高10%。本研究将纳米孔径结构和纳米粉煤灰的增韧增强有机结合，在解决泡沫炭的孔径大和韧性差的同时,又实现粉煤灰高附加值利用，具有重要的学术理论价值和广阔的应用前景。