通过溶胶-凝胶工艺及超临界干燥过程制备了苯酚-三聚氰胺-甲醛(PMF)气凝胶,考察了不同反应物配比对凝胶时间和气凝胶密度的影响,所制备的PMF气凝胶在85℃时凝胶时间在2～6 h之间,密度可低至38 mg/cm3,与传统的三聚氰胺-甲醛(MF)气凝胶体系相比,凝胶时间和密度都大大降低.采用场发射扫描电镜、N2吸脱附、红外和热重对气凝胶的结构进行了表征,结果表明,PMF气凝胶具有典型的三维网络骨架结构,其骨架是由大量纳米级的颗粒组成的;气凝胶的比表面积可达383.03 m2/g,其孔径分布主要集中在19 nm左右,是典型的介孔材料.热重分析表明,PMF气凝胶在380℃以下具有较好的热稳定性.
Phenol-melamine-formaldehyde (PMF) aerogels were prepared using phenol,melamine and formaldehyde via sol-gel method,followed by supercritical drying.The effect of different reactant ratio on gelation time and aerogel density was studied.The structural properties of PMF aerogels were characterized by the field emission scanning electron microscopy (FESEM),N2 adsorption and desorption,Fourier transform Infrared spectroscopy (FT-IR),thermogravimetric analysis (TGA) and the brunauer-emmett-teller (BET) methods.The results indicated that the gelation time of PMF aerogels was about 2-6 h at 85 ℃ and its density could be as low as 38 mg/cm3.Comparing to the traditional MF aerogel,the density and gelation time of PMF aerogel had a significant decrease.The PMF acrogel had a typical three dimensional structure made up of nano-particles with an open porous network.The N2 adsorption/desorption result showed that the PMF aerogel had a high specific surface area of about 383.03 m2/g and pore diameter of about 19 nm,which was typical mesoporous materials.According to thermal analysis,the PMF aerogel maintained good stability under 380 ℃.
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