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Authors Gao, S.-L. ; Mäder, E. ; Abdkader, A. ; Offermann, P.
Title Sizings on Alkali-Resistant Glass Fibers: Environmental Effects on Mechanical Properties
Date 04.04.2003
Number 10839
Abstract The alkali-resistant glass fibers (ARG) are coated with special sizings to provide superior alkali resistanceand are designed to reinforce cementitious and other alkali matrixes. The assessment of changes in thefiber surface nanomechanical properties is essential for understanding the fiber bulk mechanical fracturebehavior. Here we present examples demonstrating sensitive surface stiffness and dissipated energy withregard to the depth profile at the nanoscale, using atomic force microscopy with nanoindentation. Anondimensional energy index is proposed to estimate inhomogeneous surface properties and account forthe substrate effect. Additionally, the variations in surface chemistry were evaluated by Fourier transforminfrared attenuated total reflection spectroscopy and thermal gravimetric analysis. Among three types ofaqueous environments evaluated, an alkaline solution is the most aggressive to the fiber surface.Subsequently, we describe the effect of surface property variability on the fiber tensile performance usinga modified bimodal Weibull statistical distribution analysis. A new effective surface thickness factor <I><IMG SRC="/images/gifchars/kappa.gif" BORDER=0 ></I>(<I>d</I>)is given to reveal the influences of various surface treatments on the extrinsic failure. The sizing is shownto significantly affect both the population and size of flaws on the fiber surface by healing effects. Finally,we correlate the tensile strength and surface roughness with Griffith fracture predictions. The maximumheight roughness of ARG fibers follows very closely the line predicted by the Griffith fracture criterion.It highlights the importance of the sizing to <br />the environmental resistance of the alkali-resistant glassfibers.
Publisher Langmuir
Wikidata
Citation Langmuir 19 (2003) 2496-2506
DOI https://doi.org/10.1021/la020778t
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