化学沉积法改善纤维水泥基体的界面性能

为了改善合成纤维-水泥基体界面黏结性质,通过化学沉积纳米二氧化硅,制备了一系列的改性纤维.使用X射线能谱仪(EDS)确认二氧化硅的存在,采用扫描电镜(SEM)观察纳米颗粒在纤维表面的分布,从而评价化学沉积时间对沉积效果的影响,并通过单丝纤维拔出行为和塑性抗裂性能试验证实改性纤维的优势.结果表明:对聚丙烯(PP)纤维而言,合适的化学沉积时间为60 min,此时纳米二氧化硅粒子的平均粒径为300 nm；聚乙烯醇(PVA)纤维表面具有的亲水性质,使纳米二氧化硅在其上的分布形态与在PP纤维上明显不同；改性纤维的界面黏结强度显著提高,表现出优良的抗裂性能,其原因可能是由于二氧化硅的水化活性,水化产物在单丝拔出及塑性抗裂时起到了物理锚固及化学键合的双重作用.

Improvement of the Interfacial Properties of Fiber Cement Matrix by Chemical Deposition

In order to improve the interfacial bonding properties of synthetic fiber cement matrix, a series of modified fibers were prepared by sol gel chemical deposition of nano silica. The effect of chemical deposition time on modification efficiency and the distribution of nano particles on the fiber surface were observed with energy dispersive spectrometer(EDS) and scanning electron microscope(SEM). Single fiber pull out behavior and plastic crack resistance experiments were carried out to confirm the advantage of modified fiber. The results demonstrate that the proper chemical deposition time is 60min for polypropylene(PP) fiber and the mean diameter of nano silica particles is about 300 nm. As for hydrophilic property, the distribution morphology of nano silica on polyvinyl alcohol(PVA) fiber surface is obviously different. The interfacial bond strength of modified fiber matrix is improved significantly from the pull out behavior curves, therefore, all the modified fibers have excellent crack resistance property. The interfacial property of fiber matrix is improved because of hydration activity of silica. The hydration products act as chemical combination and physical anchors during pull out and crack resistance.