【作者】 潘志东；

【导师】 王燕民；

【作者基本信息】 华南理工大学 ， 材料学， 2011， 博士

【摘要】 在挤压、冲击和剪切等机械应力的作用下,机械能在材料的结构中累积,造成材料的结构和性质发生变化,提高材料的反应活性,从而激发材料的化学反应。按照机械力使材料发生化学作用的条件不同,可以大致将机械力化学分为硬机械力化学效应和软机械力化学效应。硬机械力化学方法是通过对物料施加强烈机械力作用,直接合成制备材料或对材料进行改性的方法,其缺点是研磨过程的随机性、较高的掺杂量和较大的能耗。有高活性化合物参加的机械力化学反应称为软机械力化学,这些活性物质包括:氧-氢基团、过氧化物、硝酸盐、金属碳酸盐等,活性官能团可以促进机械力作用下的化学反应,从而降低反应对机械应力强度和反应时间的要求,以达到降低能耗,减少掺杂的目的。因此,在机械应力作用下,如何有效激发材料的机械力化学效应已经成为目前制备先进材料领域的重要研究课题之一。首先,本论文描述了可用于材料振动机械力化学效应的振动磨的结构和工作原理,并从能量利用的角度分析了振动磨与其它类型研磨设备（如行星磨、搅拌磨、球磨机、冲击磨和气流磨）的各自特点。与其它研磨设备相比,振动磨具有显著的优点。振动磨对材料作用的机械应力以碰撞和挤压为主,使其适用于对材料进行机械力化学处理。振动磨的能量密度较为适中,应力速度可调节的范围较大,能量密度和比能较大,因此,可使产品产生较高的活性,促使其发生机械力化学效应。因此,振动磨可以对无机和有机材料进行有效的振动机械力化学处理,尤其适用于处理韧性物料。进而,本论文分别对无机材料（矿渣水泥）和有机材料（魔芋葡甘聚糖）的振动机械力化学效应进行了较为深入的研究,探讨了振动机械力化学处理方法应用于不同材料时的机理。本论文研究了振动机械力化学效应对矿渣水泥水化反应活性及其硬化强度的影响。结果表明,振动机械激活使矿渣水泥的颗粒粒度减小,有效增加矿渣水泥中粒径在10μm以下颗粒的含量,并使高炉渣和硅灰颗粒与水泥颗粒均匀混合,同时,机械应力的循环作用使矿渣颗粒的结构发生变形,位错等缺陷的含量增加,使其水化反应激活能降低,水化反应速度常数增大,从而促进水化反应进行。矿渣中的硅颗粒参与水泥的水化反应,有利于C-S-H在硅颗粒上成核,加快C₃S水化反应速度,促进C-S-H的形成。经机械激活的矿渣水泥样品水化后H₂O和主结构之间的结合更加紧密,随着C-S-H相的生成,SiO₄^4-的聚合度有所增加。振动机械激活可以显著提高矿渣水泥的早期硬化强度,并有助于提高矿渣的掺入量。本课题还采用振动机械力化学的处理方法对魔芋葡甘聚糖进行了脱乙酰基和磷酸盐酯化反应的研究,并探讨了经振动机械力化学改性后,魔芋葡甘聚糖的应用性能。结果表明,在振动机械力化学处理时,魔芋葡甘聚糖分子结构中的活性基团与碱性改性剂发生皂化反应可以快速有效地脱去乙酰基。碱性改性剂的碱性越强,脱乙酰基改性的效果越好。经过振动机械力化学脱乙酰基处理后,魔芋葡甘聚糖样品的溶胀性能有所改善,其水溶胶的触变性随着研磨时间的延长而逐渐减弱。在相同机械力化学处理时间下,经KOH改性的魔芋葡甘聚糖样品水溶胶的粘度比NaOH改性的样品大。脱去乙酰基以后,魔芋葡甘聚糖分子结构中拥有更多的-OH,使其有更多的机会形成分子间氢键,使魔芋葡甘聚糖分子与水分子的连接更加紧密,因此,脱乙酰基的魔芋葡甘聚糖样品具有较好的黏度稳定性,并随着改性时间的延长而增强。经振动机械力化学脱乙酰基改性后,魔芋葡甘聚糖样品在100℃左右的失重（吸附水逸出）大于原料,与NaOH相比,采用KOH对魔芋葡甘聚糖进行机械力化学脱乙酰基改性有利于减少其在受热时的总失重。另外,在振动磨机械应力作用下,魔芋葡甘聚糖中的羟基可被磷酸盐基团取代发生酯化反应。分析表明,通过振动机械力化学处理可以使魔芋葡甘聚糖与六偏磷酸钠发生酯化反应。经酯化改性,魔芋葡甘聚糖水溶胶的透光率优于原料,吸附金属离子量与原料相比较高。在改性时间为10 min时经酯化改性的魔芋葡甘聚糖样品的透光率和吸附性达到最佳值。魔芋葡甘聚糖大分子链的完整性对其絮凝能力的影响大于磷含量的影响。本研究将振动机械力化学方法应用于处理矿渣水泥和魔芋葡甘聚糖均获得了较好的结果,说明振动机械力化学具有较广泛的适用性,是一种处理材料的有效方法。更多还原

【Abstract】 The cumulation of mechanical energy in solids occurs under the effects of various mechanical stresses, such as compression, impact and shear, leading to the transformations of structure and property of solids. Therefore, the chemical reaction of material is activated by the increase of material reactivity in the mechanical stress field. The mechanochemistry is divided into hard mechanochemistry and soft mechanochemistry based on their mechanical stress difference, which induces the mechano-chemical reaction. The classic mechano-chemical effects, i.e., hard mechanochemistry, aim at the direct sythesis of a product via an intensively grinding process. The problems of using hard mechanochemical method involve unregulated grinding process, contamination and high energy consumption. Recent development is inevitably shifted toward mechano-chemical processes under softer or milder conditions. The soft mechano-chemical effects are correlated to the substances with some surface functional groups, such as OH groups, peroxide, nitrate and metallic carbonate, et al., with a higher reactivity rather than anhydrous oxides. These substances tend to perform chemical reaction under the mechanical activation and allow to decrease the level of mechanical loading under milder mechanochemical conditions, thus leading to reduction of the energy consumption and contamination. This method in the processing of advanced materials has attracted more attentions during recent years.Firstly, this dissertation described the structure and operation mechanism of vibrating mill. The energy utilization of various mills, such as vibrating mill, planetary mill, stirred beads mill, ball mill, disintegrator and jet mill, were evaluated to understand the efficient application of vibrating mill for the mechano-chemcial effect on materials used in this dissertation. The vibrating mill is a kind of efficient grinding equipment for mechano-chemical reaction of materials due to its superior characteristics like intensive mechanical stress （i.e., collision and compression）, moderate energy density and a greater adjustment range of stress rate. It is indicated that vibrating mill can be used to induce mechano-chemical effects on inorganic and organic materials, especially on some materials with a greater toughness.Secondly, this dissertation systemically investigated the mechanochemical effects on inorganic and organic materials （i.e., slag cement and konjac glucomannan） in vibrating mills. The mechanisms of mechano-chemical effects on these materials in vibrating mills were analyzed, respectively.This dissertation investigated the mechanical activation of slag cement in an intensive vibrating mill in order to accelerate the hydration and increase the mechanical strength. The results showed that the mechanical activation of slag cement in the vibrating mill could reduce the particle size of slag cement and increase the amount of particles finer than 10μm. The blast furnace slag, silica fume and cement were well mixed in the process of mechanical activation. Meanwhile, the activated slag cement particles possessed a distortion of structure and increased defects. Therefore, the slag cement particles treated by the vibrating mill show a higher rate of hydration due to the decrease of activation energy. The silica particles in slag cement could favor the acceleration of the hydration rate of C₃S by enhancing the nucleation of C-S-H on the surface of silica particles. In the process of hydration of slag cement, the activated samples showed a stronger bonding between H2O and the host structure. The polymerization degree of SiO44- increased with the formation of C-S-H phase. It was also found that the mechanical activation of slag cement in the vibrating mill could enhance the early strength development of slag cement and increase the addition amount of slag into cement, compared to unactivated slag cement.The de-acetylation and esterification of konjac glucomannan by mechano-chemical treatment in a vibrating mill were also investigated, respectively. The results showed that the mechano-chemical treatment under alkaline condition was efficient to remove the acetyls from konjac glucomannan. The alkalinity of modifier could dominate the efficiency of de-acetylation of konjac glucomannan. The swelling property of konjac glucomannan de-acetylated by mechano-chemical treatment in the vibrating mill was improved. The measurement of the konjac glucomannan gel rheology indicated that the mechano-chemical treatment could reduce the thixotropy in the de-acetylated konjac glucomannan. The de-acetylated konjac glucomannan treated by KOH exhibited a higher viscosity than that treated by NaOH. The konjac glucomannan after deacetylation possessed the more hydroxyl groups. The molecules of deacetylated konjac glucomannan could form the more inter-molecular hydrogen bonds, leading to an enhanced connection between konjac glucomannan molecules and water molecules. Therefore, the de-acetylated konjac glucomannan samples possessed a higher swelling property and a greater viscous stability, showing a positive relation with grinding duration. According to the thermogravimetric analysis, the de-acetylated konjac glucomannan samples showed a higher mass loss （around 100 oC） due to the loss of hydroxyl groups of konjac glucomannan, compared to the original konjac glucomannan sample. The mass loss of konjac glucomannan sample treated by KOH was lower than that by NaOH. This illustrated that KOH could be more effective to reduce the mass loss of konjac glucomannan.In addition, the esterification of konjac glucomannan with sodium hexametaphosphate was stimulated by mechano-chemical treatment in a vibrating mill. The aqueous solutions of konjac glucomannan showed a higher transmittance after mechano-chemically esterification. As a flocculant, the treated konjac glucomannan adsorbed more metallic ions rather than the non-treated konjac glucomannan sample. The optimized duration of mechano-chemical treatment of konjac glucomannan for the superior transmittance and adsorption property was 10 min. It was found that the effect of formation of backbone of konjac glucomannan on the adsorption property of konjac glucomannan dominated over the effect of phosphorus content of konjac glucomannan.更多还原