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石膏微结构和缓凝机理研究

发表时间:2010-09-30  浏览量:1252  下载量:417
全部作者: 邓玉和,陈旻,宣玲,韩振华,王军,周梅,陈琛,王宁生
作者单位: 南京林业大学木材工业学院
摘 要: 通过原子吸收光谱仪和扫描电镜(scanning electron microscope,SEM)等现代仪器分析技术,分析不同缓凝剂对石膏水化过程中Ca2+浓度和石膏结晶形态的影响,以及pH值对柠檬酸缓凝效果的影响,探讨不同缓凝剂的缓凝机理,为今后研制更适合石膏刨花板生产的缓凝剂奠定理论基础。研究表明:柠檬酸(citric acid, AC)是一种有机缓凝剂,其缓凝机理不是由于它影响了初始液相过饱和度,而是它加入后,一方面和液相中的Ca2+发生螯合反应,阻止了液相中Ca2+与SO42-以及水的结合,有效地抑制了液相中Ca2+的剧烈消耗;另一方面生成的柠檬酸钙包覆在新生成的二水石膏晶核上,延缓了二水石膏晶核的形成和生长。而无水Na2CO3(无机缓凝剂)主要通过沉淀附着作用延缓石膏的水化进程,由于缺少了螯合作用对液相中Ca2+剧烈消耗的控制,故其缓凝效果远远不如柠檬酸。
关 键 词: 木材科学与技术;缓凝剂;柠檬酸;碳酸钠;缓凝机理;石膏结晶体
Title: Microstructure and retarding mechanism of gypsum
Author: DENG Yuhe, CHEN Min, XUAN Ling, HAN Zhenhua, WANG Jun, ZHOU Mei, CHEN Chen, WANG Ningsheng
Organization: College of Wood Science and Technology, Nanjing Forestry University
Abstract: The retarding mechanism of different retarders was explored by analysing the concentration of Ca2+ in the hydrating system, the morphology of gypsum crystals and effect of pH value on the retarding efficiency of citric acid with some modern instruments, such as fire atomic absorption spectrophotometer (FAAS), scanning electron microscope (SEM) and so on. Test results showed that the retarding efficiency of inorganic retarder is very different from that of organic retarder. As an organic retarder, citric acid has no effect on the initial supersaturation of the hydrating system, but holds back the combination of Ca2+, SO42- and water by chelated reaction with Ca2+ in the liquid. Meanwhile, the calcium citrate covers the surface of the nuclear of dihydrate gypsum crystal. So the form and growth of dehydrated gypsum crystal are delayed. In contrast, anhydrous sodium carbonate (a kind of inorganic retarder) delays the hydrating process by the adhering of calcium carbonate to the gypsum crystal. Its lacking of chelated reaction leads to quite poor retarding efficiency compared with citric acid.
Key words: wood science and technology; retarder; citric acid; sodium carbonate; retarding mechanism; gypsum crystal
发表期数: 2010年9月第18期
引用格式: 邓玉和,陈旻,宣玲,等. 石膏微结构和缓凝机理研究[J]. 中国科技论文在线精品论文,2010,3(18):1904-1911.
 
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