الفهرس 
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Abstract
Cellulose, due to its natural abundance and unique properties, is undoubtedly one of the most promising renewable and biodegradable raw materials for the large scale production of chemicals, fuels, and materials in a bio-based economy. In order to develop eco-friendly polymeric materials, the chemical modification of cotton linters is the main object of this study which concentrated mainly into three parts.
First, Microcrystalline cellulose (MCC) was derived from cotton linters by acid hydrolysis with different concentrations of HCl (2.5- 15%). Infrared spectroscopy and thermal analysis were used to follow the effect of hydrolysis on the molecular structure of the produced microcrystalline cellulose. Scanning electron microscope images and X-ray diffraction were also studied for more information about the crystallinity, fiber length, particle size, and shape of the produced microcrystalline cellulose. The obtained results showed that the crystallinity index of the hydrolyzed cotton increased by increasing acid concentration and then began to decrease at 15% HCl to value of 71.4%. The hydrolyzed cotton linters had a lower kinetic energy than the untreated sample. Moreover, the hydrolyzed cotton linters with high concentration of HCl (15%) had a lower kinetic energy with value of 100.25 cal. than those treated with lower concentration (5%) with value of 114.8 cal.
On one hand, the second part, chemical phosphorylation of cotton linter (CL), activated cotton linter (ACL), and prepared MCC hydrolyzed with 5% HCl was carried out using heterogeneous (H3PO4/P2O5/Et3PO4/hexanol) method and homogeneous (dissolved CL in phosphoric acid) method. The structure and properties of the prepared cellulose phosphate samples were evaluated using elemental analysis for phosphorus, FT-IR, and TGA. The adsorption of different heavy metals (copper and cadmium) was also studied. It was demonstrated that this method proposed showed to be adequate for obtaining products with DS values up to 1.0, which is comparable to the maximum DS obtained by the most widely used methods. Chemical bonding was confirmed by FT-IR spectroscopy (a new band observed at at wavenumber 980 and 1194 cm-1 due to the presence of C-O-P bond). TGA analysis evidenced the stability of samples up to 200ºC allowing the application of cellulose samples in process arriving at higher temperature.
Finaly, the third part, cellulose-based hydrogels were prepared from cotton linter, prepared MCC from hydrolysis with 5% hydrochloric acid, and commercial MCC with and without activation by sodium hydroxide applying grafting copolymerization of PAM or AA onto cellulosic materials in the presence of KPS as initiator and MBA as crosslinker. The structure and properties of the prepared hydrogel samples were evaluated by Infrared spectroscopy (FT-IR), thermal analysis (TGA), and Scanning electron microscope (SEM). Also, the swelling properties and salt-sensitive were investigated by measuring the swelling ratios percent. Grafting of AA & PAM onto the cellulose skeleton was confirmed by FT-IR spectroscopy. SEM micrographs verified that the prepared hydrogel samples have porous sponge structure. from the swelling behavior study, it was found that AMCC-AA hydrogel is more swellable than other hydrogel samples, moreover, sensitive to hot water and saline solution (NaCl).
Keywords: Cotton linter; Microcrystalline cellulose; FT-IR, TGA; SEM; Kinetic energy; Cellulose phosphate; metal ion uptake; cellulose based hydrogels; swelling ratio.