摘要
无宏观缺陷 (MDF)水泥基复合材料的水敏性问题是这种高抗折强度材料的致命弱点 .本工作研究了高铝水泥 /聚乙烯醇基MDF复合材料吸湿后对其物理力学性能和微观结构的影响 .结果表明 ,MDF复合材料在 1 0 0 %相对湿度中的吸湿过程初始受扩散动力学控制 ,吸湿量取决于聚合物的含量 ,水透过复合材料的扩散系数为1 0 -8cm2 /s数量级 ;其在水中的强度随浸水时间的延长连续下降 ,同时伴有不可忽视的线性膨胀 .MDF复合材料的XRD ,DTA ,IR以及SEM分析显示 ,环境水的侵蚀将引起聚合物化学改性并使未反应水泥颗粒继续水化 ,并导致水泥 /聚合物界面削弱 .另外 ,MDF复合材料的水敏性改性措施也被提出 .
Water sensitivity is a fatal weakness for macro_defect_free(MDF) cement based composites with a high flexural strength. The effects of moisture adsorption on the physical and mechanical properties and microstructure of the MDF composites based on high alumina cement and polyvinyl alcohol were studied. The results show that the moisture adsorption process of the MDF composites during initial hydration period is diffusion_controlled,the amount of adsorption depends on the content of polymer, and the diffusivity of water in the MDF composites is of the order of 10 -8 cm 2/s. Upon immersion in water, the MDF composites have a continuous drop in strength, accompanying with a substantial linear expansion. Examinations of the MDF composites by XRD, DTA, IR and SEM reveal that water immersion leads to chemical modification of the polymer phase and rehydration of unreacted cement grains in the composites, resulting in weaknesses of the interface between cement and polymer. Moreover, the strategies to improve the water sensitivity of the MDF composites are proposed.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2000年第4期325-330,共6页
Journal of The Chinese Ceramic Society
基金
高等学校博士学科点专项科研基金!项目 ( 94 4970 2 )
关键词
无宏观缺陷
水泥基复合材料
水敏性
改性
macro_defect_free cement based composites
water sensitivity
mechanism
modification
