Scientific investigations on the non-chemical modification of lignocellulosic fibers are important for engineers when they design green wood-plastic composites. Two types of lignocellulosic fibers, namely rice husk and rice straw fibers, were studied. The physicochemical and thermal properties of the fibers with and without seawater modification were compared. The results suggested that seawater modification improved the physicochemical and thermal properties of the fibers, and that it specifically increased the surface roughness, crystallinity, and pyrolysis temperature at 5% weight loss, and decreased the silicon, hemicellulose, and lignin content of the fibers. Compared with rice husk fibers, rice straw fibers exhibited a high growth ratio of crystallinity and pyrolysis temperature at 5% weight loss, and a high loss ratio of silicon. Seawater modification of rice husk and rice straw fibers could improve fiber–polymer compatibility.

Wear Properties of Wood-plastic Composites Pretreated with a Stearic Acid-palmitic Acid Mixture before Exposure to Degradative Water Conditions

Lignocellulosic fibers have been widely used to reinforce polymer composites. Chemical modification of the fibers can improve the fiber properties and fiber-polymer interfacial compatibility. This study considered an eco-friendly process that can reduce environmental pollution by modifying lignocellulosic fibers using seawater rather than chemical reagents. The effects of seawater modification on the physical, chemical, and thermal properties of lignocellulosic fibers obtained from wheat straw were investigated. After seawater modification, the modified fibers had a lower number of hydrogen bonds, hemicellulose, lignin, and silicon content, and higher water absorption, crystallinity, surface roughness, and thermal stability. Considering the essential components of seawater, the contribution of NaCl during the modification process was the most significant, followed by that of the bivalent salts (MgCl₂ + CaCl₂ + SrCl₂), Na₂SO₄, and trace-component (KCl + NaHCO₃ + KBr + H₃BO₃ + NaF).