This work aims to study the effect of chemical treatments of date stone flour (DSF) as a filler on the elastic properties of biocomposites based on green epoxy resin (GER) used as a matrix. The main disadvantages of natural reinforcements in biocomposites are the poor compatibility between the reinforcement and the matrix as well as the relatively high moisture sorption. Different chemical treatments using soda (alkaline), benzoyl chloride, and potassium permanganate were applied to the DSF filler. Then, the filler was incorporated into the matrix at 30 wt % to obtain GER/DSF biocomposites. The elastic properties of the biocomposites, namely, longitudinal modulus, shear modulus, bulk modulus, Young's modulus of elasticity, acoustic impedance, Poisson's ratio, and ultrasonic microhardness, were determined using ultrasonic through-transmission method. In addition, the morphology was studied using microscopy analysis. The results obtained revealed a decrease of the elastic properties of the pretreated-filler biocomposite compared to the pure GER. On the other hand, the chemical treatment of the filler leads to an improvement of the elastic properties of GER/DSF biocomposites. The permanganate treatment is the most suitable for GER/DSF biocomposites. The morphology analysis through optical microscopy and scanning electron microscopy showed that chemical treatments enhance the interfacial adhesion between the DSF filler and the GER matrix.

By trying to increase the luminosity or the life expectancy of an incandescent lamp, an idea consists of a series of successive rolling up of the tungsten filament. This gives geometrical configurations of filaments named simple, twin, or triple helical spring, etc. . . In this paper, we will limit only to the cases of the simple and twin helical spring filaments. Under the combined effects of the high temperature and the stresses induced by its own weight, the filament creeps by becoming plastically deformed in a permanent and a continuously manner, until the rupture. The theoretical study of the behaviour of these filaments needs the knowledge of internal efforts distribution, deformations modes, and their evolutions. The present work consists on an elastic structural analysis which must be the first step. Since the objective is also to study the influence of the filament self-weight solicitation, the orientation (or position) with respect to gravitational direction should be taken into account. Numerical results are obtained by finite element method. They showed a negligible influence of the solicitations due to the variation of the temperature with respect to those of the self-weight, and a relative sensitivity to the position changes for the twin helical spring filament. For this later, we have developed an analytical method which is only valid in the case of a vertical position. Because of some difficulties, the comparison between the numerical and analytical results could not be carried out directly. However, the analytical approach proved to be qualitatively useful for the analysis of numerical results.

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The paper deals with the effect of date stone flour (DSF) as a filler on the elastic properties of biocomposites based on two different matrices, namely, polymethyl methacrylate (PMMA) and green epoxy resin (GER). Potassium permanganate treatment was applied to improve the surface properties of the DSF filler. Fourier transform infrared spectrotroscopy was used to analyze the chemical changes of the functional groups in the untreated DSF and the permanganate treated DSF filler. Different filler content of 10, 20, and 30 wt%, respectively, were used to obtain PMMA/DSF and GER/DSF biocomposites. The elastic properties, namely, longitudinal modulus, shear modulus, bulk modulus, Young’s modulus of elasticity, Poisson ratio, ultrasonic micro-hardness, and acoustic impedance of the biocomposites were determined using the ultrasonic through-transmission method. In addition, the morphology was studied using optical microscopy and scanning electron microscopy. Fourier transform infrared spectrotroscopy analysis results revealed the success of the permanganate treatment. The elastic properties of PMMA/DSF biocomposites were decreased, while an improvement of these properties is observed for GER/DSF biocomposites. Morphological results showed the presence of pores and cracks in the PMMA/DSF biocomposites, which is attributed to poor interfacial adhesion between the DSF filler and the PMMA matrix. However, fewer defects were observed in the GER/DSF biocomposites, which is due to better interfacial adhesion between the DSF filler and the GER matrix.