硅酸盐玻璃中SiO_4^(4-)四面体聚合分布的研究——Ⅲ.Na_2O-CaO-SiO_2玻璃的聚合结构

A STUDY ON THE POLYMERIC DISTRIBUTION OF SiO_4^(-4) TETRAHEDRON IN SILICATE GLASSES Ⅲ.POLYMERIC STRUCTURE OF Na_2O-CaO-SiO_2 GLASSES

本文在前两文基础上,进一步研究了Na_2O-CaO-SiO_2玻璃的聚合结构。玻璃经三甲基硅烷化(TMS)反应后,用气相色谱(GLC)和凝胶色谱(GPC)测定可溶性TMS产物的聚合分布;用元素分析仪测定不溶性TMS产物的C和H的含量,并由此推导出其结构形式。实验结果表明,在所研究的22种玻璃中,SiO_4^(4-)四面体的聚合形式分为四类:低聚物、高聚物、三维网络碎片和三维无限网络。玻璃中硅酸阴离子团的聚合度随SiO_2含量的增加而增加,Na_2O/CaO比值η对之也有影响。实验结果证实了玻璃结构聚合物理论提出的观点。初步认为,Na_2O-CaO-SiO_2系统玻璃结构可按组成划分为组群状结构区、三维网络碎片结构区、三维无限网络结构区和疏松网络结构区等四个区域。

In this paper, polymeric structure of Na_2O-CaO-SiO_2 glasses is studied on the basis of two previous papers. Polymeric distribution of soluble trimethylsilylation(TMS) derivatives is separated by gas-liquid chromatography(GLCC) and gel-permeation chromatography(GPC); C and H contents of insoluble derivatives are determined by means of element analytic instrument after TMS reagent reacts on the glass. Experimental results indicated that there are four types of SiO_4^(4-) tetrahedron polymerization in a definite distribution in the glasses considered, that is, low-molecular-weight polymers, highmolecular-weight polymers, three dimensional network fragments and three dimensional infinitive networks. It is found that the degree of polymerization among SiO_4^(-4) tetrahedrons not only increases with SiO_4 content, but also relates to Na_2O/CaO molar ratio. The concept proposed in the polymer theory of glasses is then proved. Four structural regions existed in the glasses are given by the authors, i.e., isolated-form structure, three dimensional network fragment structure, three dimensional infinitive network structure and loose three dimensional network structure.