聚羧酸系减水剂在石膏颗粒表面的吸附特性及其吸附-分散机理  

Adsorption Characteristics of Polycarboxylate-type Superplasticizers on the Surface of Gypsum Particles and Its Adsorption-dispersion Mechanism

作　　者：彭家惠[1] 瞿金东[1] 张建新[1] 陈明凤[1] 吴彻平[1] 

机构地区：[1]重庆大学材料学院,重庆400045

出　　处：《四川大学学报（工程科学版）》2008年第1期91-95,共5页Journal of Sichuan University (Engineering Science Edition)

基　　金：国家自然科学基金资助项目(50572126)

摘　　要：采用紫外吸收光谱分析、微电泳仪、光电子能谱分析技术研究聚羧酸系减水剂(Polycarboxylate-type super-plasticizer,PCS)在石膏表面的吸附特性、表面电化学性能及其对石膏浆体流动度经时性的影响。结果表明,石膏表面钙元素2p电子结合能发生了明显的化学位移,PCS在石膏颗粒表面为化学吸附,其吸附等温线基本符合Lang-muir等温方程,吸附热20.85 kJ/mol,吸附层厚度7.5 nm;聚羧酸为梳状吸附,吸附量较小,静电斥力效应较弱,其分散作用主要来自于吸附层空间位阻效应。空间位阻效应产生的分散性受石膏水化作用的影响较小,因而具有良好的分散稳定性。By using UV adsorption spectrophotometer, micro-electrophoresis potential analyzer, and X-ray photo spectroscopy, the adsorption characteristics and surface electrochemical properties of polycarboxylate-type superplasticizer（PCS） on gypsum surface and their subsequent effects on fluidity loss of fresh gypsum plaster with hydration time were studied. The results indicated that the adsorption behavior of PCS on gypsum particles follows a Langmuir isothermal adsorption model with an adsorption heat of 20.85 kJ/mol and an adsorption layer thickness of 7.5 nm. The 2p electron bonding energy of Ca element on gypsum surface takes place obvious chemical shift before and after the adsorption of PCS, which suggests that the adsorption of PCS belongs to chemical adsorption. The adsorption conformation of PCS superplasticizer is comb-shaped, so it has a saturated low adsorption amount and a weak electrostatic repulsive effect, and its dispersion mainly comes from high steric hindrance effect generated by the adsorption layer. The steric hindrance is less affected by new hydration products, resulting in good dispersion stability.

关 键 词：石膏 减水剂 吸附 Ζ电位 空间位阻效应 静电斥力效应 

分 类 号：TQ423[化学工程]