MDF水泥基复合材料的微观结构与水敏性关系研究Ⅰ——胶结相渗透特性与湿度吸收

Investigation on Relation Between Microstructure and Water Sensitivity of Macro Defect Free Cement Based CompositesⅠ——? ?Percolative Characteristics and Moisture Absorption of Binder Phase

研究了 HAC/ PVA基 MDF复合材料微观结构中胶结相的分布、渗透性能与湿度吸收。所研究的 MDF复合材料中 ,其胶结相由 78vol%的界面相和 2 2 vol%的本体聚合物相构成 ,而 PVA约 35 vol%存在于界面相中 ,6 5 vol%分布于本体聚合物区域。 MDF复合材料中经热处理后的孔结构测定结果显示 ,孔径 30～ 1 0 0 A的细尺度孔来源于界面相水化产物的分解 ,而孔径 >2 0 0 的大尺度孔来源于本体聚合物中 PVA的分解。湿度吸收试验研究表明 ,尽管界面相物相区域形成了湿度渗透的通道 ,但界面相中交联的 PVA对湿度传递的贡献很小。相反 ,本体聚合物区域是湿度传递的主要通道。根据上述认识 ,提出了改善

The distribution, percolative characteristic and moisture adsorption of the binder phase in the microstructure of macro defect free composites made from a high alumina cement(HAC) and a polyvinyl alcohol(PVA) are studied. For the composites studied, it was determined that the interphase comprised 78 vol% of the binder phase content, while the bulk polymer phase comprised 22 vol% of the phase, and 35 vol% of the total PVA was located in the interphase regions, while 65 vol% of the total PVA was located in the bulk polymer regions. The results of the pore structures for the heat treated MDF showed that the smaller pores with a radius between 30 and 100A resulted from the decomposition of the hydrates in the interpase regions , while the larger pores above 200A in size resulted from the decomposition of the PVA in the bulk polymer regions. The experiments for moisture adsorption show that the interphase regions form a percolative pathway through the MDF composite microstructure, but their contribution to the transport of moisture is limited. In contrast, the bulk polymer regions provide the dominant transport pathway. Based on this knowledge, the technological principals for improving the water resistance of the MDF composites have been proposed.