Surface Modification of Polymeric Fibers to Control the Interactions with Cement-Based Matrices in Fiber-Reinforced Composites

Abstract

There is evidence that the fiber-matrix interaction in fiber-reinforced cementitious composites is determined by the wettability and roughness of the fibers. Due to the high ionic strength in the hydrated cement, also the surface charge or acid/base behavior of the fibers is assumed to play a role. To create fibers with alkaline and acidic surface functionalities, water-insoluble poly (vinyl alcohol) fibers were permanently modified by adsorption of various polyelectrolytes. X-ray photoelectron spectroscopy, zeta potential, and contact angle measurements revealed acidic, alkaline or amphoteric fiber surfaces with advancing water contact angles between 34° and 58°. In a first step to study the interaction with cementitious materials, the interaction of these fibers with pore solution (the liquid phase of hydrated cement) and the adsorption of calcium ions on the fiber surface were investigated. The work will be continued by studying the fiber-matrix interaction in cementitious matrices and its influence on the composite strength.