الفهرس 
Chapter 1: IntroductionOnly 14 pages are availabe for public view
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Abstract
Huge amounts of rice straw waste are left every year in different areas of the world; these residues still cause environmental problems due to unsafe practices such as burning. Isolation of nanomaterials such as cellulose nanofibers represents an effective way for utilization of rice straw in advanced products. The first part of my thesis aimed at evaluating the properties of rice straw cellulose nanofibers isolated from bleached and high-lignin unbleached pulps using a multi-criterion quality index, which allows a benchmarking analysis between different sources, processes and features. Rice straw was subjected to neutral sulfite pulping process to obtain the high-lignin unbleached pulp while the bleached pulp was obtained by bleaching the produced pulp with NaClO2/acetic acid mixture. Using mechanical pretreatment (Valley beater), and ultrafine friction grinder both bleached and unbleached pulps were used to obtain cellulose nanofibers with and without lignin (LRSNF and RSNF, respectively). Nano paper sheets were prepared from both types of nanofibers and characterized using tensile tests, optical microscopy, atomic force microscopy, electron scanning microscopy, water contact angle and surface energy. Cellulose nanofibers generated from rice straw were scored using a multi-criterion quality index depending on characterization using eight tests (nanosized and macro size fraction, turbidity, Young’s modulus, porosity, transmittance, tear resistance, and homogeneity).
Natural materials that inspired the creation of next-generation Bio-nanocomposite with lower frication coefficients, decreased wear, and superior mechanical and tribological performance. In the current study, Cellulose nano-fibers (RSNF) derived from bleached rice straw pulp and Cellulose nano-fibers containing lignin (LRSNF derived from unbleached rice straw pulp were prepared. Different ration from RSNF and LRSNF (2.5,5,7.5 and 10 wt%) were introduced to Ultra-high molecular weight polyethylene (UHMWPE) using Twin Screw Extruder (TSE) process and followed by injection moulding technique. When compared to pure UHMWPE, RSNF/UHMWPE and LRSNF/UHMWPE composites showed significantly increased hydrophilicity when cellulose nano fibers are added, as well as considerable improvements in mechanical properties and tribological features, with a particularly substantial improvement with LRSNF with reduced frication and wear loss. As the first investigation, this comparison clearly demonstrated the role of lignin in the tribological properties of bio-nanocomposites.