Effects of Different Plasma Treatments of Short Fibers on the Mechanical Properties of Polypropylene-Wood Composites

摘要

In this work, a custom-made reactor was developed to treat batches of short wood fibers with plasma. Three different plasma gases were tested: air, methane (CH4) and sulfur hexafluoride (SF6). The latter showed very promising results and was therefore used to prepare additional samples to determine the effects of plasma treatment and conditions on the wood fiber surface properties as well as the adhesion in a polypropylene matrix. As a result, composites made out of fibers plasma treated for 40 min at 60 W demonstrated an increase in the elastic modulus of more than 25%. Scanning electron microscope micrographs of the composites' fracture surfaces indicated stronger interactions between treated fibers and the matrix. The incorporation of fluorine on treated fiber surfaces, mostly in covalent bonds with carbon, was clearly observed and analyzed by X-ray photoelectron spectroscopy. The water contact angle on wood specimens treated under similar conditions displayed hydrophobic to superhydrophobic behavior, with contact angles exceeding 130 degrees. (C) 2016 Society of Plastics Engineers