(343g) Surface Engineering of Natural Fibers for Composites Using Atmospheric Pressure Plasma

The interest in natural fiber composites has increased significantly due to the high demand for greener, low-cost products for many applications.  Natural fiber composites, however, have two main drawbacks, including poor adhesion to the resin matrix, which worsens mechanical properties of the composite, and high absorption of water.  Surface treatment and coatings have been investigated to overcome these challenges, including chemical treatments, biological methods, and plasma treatment.  Each treatment type has disadvantages, including long treatment times, hazardous chemicals, high solvent and waste handling, high cost manufacturing, and/or only marginal improvements in performance.  The surface treatment approaches used in this investigation overcome the disadvantages of other methods and offer a promising alternative for improving performance of natural fiber composites.  Atmospheric plasma treatments, grafting, and coatings were applied to surfaces of natural cellulose fibers and tested in composites.  Pulsed atmospheric plasma using air as the plasma gas was used for surface activation, as well as grafting and cross-linking of coatings.  Chemicals used included organosilicon and organic reagents, including vinyltriethoxysilane and epoxy.  The fibers were processed by plasma pre-treatment, application of the chemical reagent, and plasma exposure for grafting and cross-linking the coatings.  Comparisons were made among chemical reagents and variations in processing, such as omitting the plasma exposure step after application of the reagent, as well as adding multiple layers.  The fibers were evaluated using wettability and X-Ray Photoelectron Spectroscopy to evaluate the surface property and chemical changes that occurred from processing.   Epoxy composites were prepared with the fibers and tested for tensile strength to compare the surface treatment methods and reagents.