Polypropylene fiber-matrix bonds in cementitious composites

It is known that for creating advanced polyolefin/cement-based composites the polymer surface should be converted into a layer which is compatible with the inorganic component. In this respect, plasma chemistry offers additional solutions to the wet chemistry approach. It. has been demonstrated during the last decade that cold plasma-mediated reactions are suitable for etching and surface functionalizing even the most inert polymeric substrates, including Teflon, polypropylene (PP), and polyethylene (PE), In this paper composite preparations from SiCl4-cold plasma and chromic acid-treated fibrillated PP substrates and cement are described. The nature of plasma- and wet chemistry-induced surface functionalization and etching processes was monitored using survey and high-resolution X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and dynamic water contact angle measurements. It has been demonstrated that the plasma-exposed surfaces result in increased adhesion between the fibers and the cementitious matrix in comparison with the chromic acid-modified fibers. It has been shown that the improved tensile strength values can be related to the treatment-generated polar surface functionalities as well as roughness.