矿物聚合材料:研究现状与发展前景

MINERAL POLYMER: CURRENT DEVELOPMENTS AND PROSPECTS

矿物聚合材料是以铝硅酸盐矿物或工业固体废物为主要原料 ,以高岭石作配料 ,硅酸钠作结构模板剂 ,氢氧化钠作激活剂而制成的一类新型无机非金属材料。其形成过程为 :铝硅酸盐固体组分的溶解络合、分散迁移、浓缩聚合和脱水硬化。由铝硅酸盐凝胶相形成的基体相 ,其化学组成与沸石相近 ,微结构极可能与蛋白石类似 ,物理形态上呈三维网络结构 ,将未溶解的固体颗粒胶结为坚硬块体 ,是材料获得良好力学性能和化学稳定性的结构基础。矿物聚合材料的性能主要受配料组成和聚合反应的动力学过程所控制 ,其抗压强度随固化时间的延长而呈抛物线式发展。系统研究配料组成和固化条件对铝硅酸盐聚合反应的影响 ,建立表征矿物聚合材料组成结构性能的物理模型 ,是对其进行结构性能设计的理论基础 ,也是利用铝硅酸盐聚合反应实现工业固体废物资源化的技术关键。

Geopolymer (or mineral polymer) is a new category of inorganic nonmetal materials, which is manufactured mainly from various aluminosilicate minerals or industrial solid wastes, with metakaolin as ingredient, liquid sodium silicate as structural template, and sodium and/or potassium hydroxide solution as activator. Four stages are included in the formation process of mineral polymers, i.e., solution of aluminum and silicon from solid particles, and complex in the liquid; diffusion from the particle surface into interstitial space; concentrating and polymerization of the components by chemical reaction to form interstitial aluminosilicate gel; and removal of extra water and solidification of the gel phase. The matrix phase so formed in geopolymer is similar to zeolite in chemical composition, possibly being an analogue of opal in microstructure, and a three dimensional network in physical framework to encapsulate the insoluble solid particles, which is a structural foundation for geopolymeric materials with excellent mechanical performance and chemical stability. The properties of geopolymer vary obviously with component concentrations in the system and the dynamic process of geopolymerization; especially compressive strength is developing paradoxically with solidifying time. Understanding how each component in a system and the solidifying condition influence aluminosilicate polymerization is eagerly needed for establishing a physical model to characterize phase component, structure, and properties of geopolymer, which is a theoretical foundation for designing the materials, and also a key for the technique to manufacture geopolymeric materials from industrial solid wastes by aluminosilicate polymerization.