新型无氨凝胶的制备与胶凝特性研究

采用光电分析法研究了环保型无氨凝胶防灭火材料,比较了三种促凝剂与水玻璃生成无氨凝胶的胶凝特性,并研究了具有较好胶凝特性的促凝剂C与水玻璃在不同浓度、不同温度下的成胶特性及其失水性和热稳定性。结果表明:促凝剂C对水玻璃的促凝效果较好,生成的凝胶强度高、失水率低;当水玻璃浓度为7%、促凝剂C浓度为1.8%～3.0%时,对成胶过程有利;由浓度为7%的水玻璃与浓度为2.5%～3.0%的促凝剂C生成的凝胶失水速率最小;温度大于80℃时,凝胶失水速率随温度升高快速增大;凝胶在不同阶段的失水速率满足不同的动力学特征,初期主要受表面控制,中期为扩散控制。水玻璃成胶特性与促凝剂中阳离子的化学价有关,高价阳离子更有助于凝胶的生成。

Preparation and Coagulating Characteristics of New-type Ammonia-free Gel

The fire extinguishing material of environmentally-sound ammonia-free gel was developed by using photoelectric analysis method.The coagulating characteristics of new-type ammonia-free gel produced by three types of coagulants and water glass were compared,and the gel-forming characteristics,the nature of water loss and the thermal stability of coagulant C with good gelling characteristics and water glass were studied with different concentrations and different temperatures.The results show that the coagulating effect of coagulant C on water glass is better,and the gel is of high strength,low water loss.It is beneficial for the process of gel-forming that the sodium silicate concentration is 7% and the concentration of coagulant C is 1.8%—3.0%.The gel formed with 7% of the sodium silicate concentration and 2.5%—3.0% of the concentration of coagulant C is of the minimum rate of water loss.When the temperature is higher than 80 ℃,water loss rate of gel will increase rapidly with the increase of temperature.Water loss rates of the gel at various stages satisfy the different dynamic characteristics,it is mainly the surface control at the initial stage and diffusion control at intermediate stage.The gel-forming characteristcs of water glass are related to the chemical valence of cations in coagulant and high valence cation is more helpful to the gel generation.