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Increasing ecological concerns have given rise to renewed interest in the use of natural materials, considering their renewability and possibility of disposal at the end of their life cycle without damage to the environment. In this study, we examined the isolation of cellulose from Esparto ''Stipa tenacissima'' of Eastern Morocco by two different ways; the first one using an acetic acid solution catalyzed by nitric acid. The objective is to determine the optimum amount of this catalyst needed to the extraction. The second way consists to study the cellulose extraction with change of the alkaline solution concentration in order to choose the required value. The cellulosic samples were characterized by FT-IR spectroscopy and X-ray diffraction, the morphology of the isolated fibers was investigated by optical microscopy. Thermal analysis (DT-TGA) were carried out to study the thermal behavior of the cellulose isolated compared with the control sample. The degree of polymerization (DP) of the samples extracted is estimated from the intrinsic viscosity value using the Mark-Houwink equation in two different solutions (DMAc/9%LiCl) and (6%NaOH/4%urea/90%H 2 O). We have demonstrated that the extraction using an acetic acid solution has been very successful by adding 2% in volume of nitric acid (HNO 3 ). However, the extraction process using an alkaline solution (NaOH; 1M) is preferable because of the absence of acetylating reaction and the high purity and the nondegradation of the resulted fibers.

In this work, Zn co-doped tungsten bronze having nominal formula Ba5CaTi1.94Zn0.06Nb8O30 has been synthesized and systematically studied for structure, dielectric and electrical properties.