The present work deals with the valorization of the lignin. The lignin is a by-product of the black liquor of the paper industry, which has a very complex composition structure. In this study, this lignin is obtained from the Alfa grass (Stipa Tenacissima L, also named Esparto grass). A composite material with polymer matrix (unsaturated polyester) reinforced with the lignin at various proportions has been elaborated and a comparison of its mechanical and physico-chemical characteristics to another type of composite material constituted of polymer matrix (unsaturated polyester) reinforced with Alfa fibers has been achieved. The characterization of these composites materials is based on tensile as well as thermal degradation tests under isothermal conditions. In order to explain the deviation from the linear profile (weight losses), a mathematical model has been used to show that the degradation energy is the same for all temperature ranges. This model allowed us to calculate the activation energy (48 kJ/mole.K), which corresponds to the process of off-gassing, break of macromolecular chains and weight loss.

Fe‒Si alloys are widely used as transformer magnets and magnetic cores because of their excellent soft magnetic properties. Fe60Si40 powders were milled in a high energy planetary ball mill (Rctsch PM400) under argon atmosphere at different time of milling. The metal powders obtained have an average diameter d50 of 2.5 to 6 um. The introduction of Si into Fe can result in a decrease of magnetic anisotropy (therefore leading to a decrease of coercivity). The nanocomposite magnetic cores were made from the Fe60Si40 powder obtained by high energy ball milling for different milling time. The particles of powder were mixed with unsaturated polyester (UP) to obtain toroidal cores. The polymerization process was made under a magnetic field H-500 Am. and ensured a preferential orientation of powder particles. Influences of the metallic powder fraction on soft magnetic properties as well as thermal increase under isothermal conditions were investigated along with the possibility to control these properties with the size and amount of powder fraction. It was also found that the soft magnetic properties of the polymer composites can be controlled in a wide range and depends on the mass fraction of the metallic powder Fe60Si40 in the composite, on shape and size of the powder particles and their orientation in the composite.

Fe60Si40 (at.%) alloys were synthesised using a planetary ball mill. X-ray diffraction was used to identify and characterise various phases formed during the milling process. Mössbauer and electromagnetic methods were used to characterise the variations in structure and their influence on the local change of magnetic properties. The shape of hyperfine field distributions used to describe the Mössbauer spectra is discussed. It was found that after 4 h of milling, α-FeSi and Fe3Si starts to form. The coexistence of the α-FeSi phase and Fe3Si was found between 8 and 16 h. After 32 h of milling, the powder was completely transformed into the alloy phase (Fe3Si). The value of the mean particle size of our samples decreases with increasing milling time. It reaches the value of 0.42 μm after 56 h of milling. The crystallite size was reduced to 13 nm after milling. The coercitive field HC decreases with increased milling time.

Nanomaterial Cr75Ni25 alloy with a mean crystallite size of 8.3 nm and microstrain of 1.23% after 48h of milling was synthesized by mechanical alloying using a high energy planetary ball milling. The morphological changes and particles size were investigated by scanning electron microscopy and laser diffraction. Magnetic results were measured by Foucault currants, coercive field and residual magnetisation. Structural change during ball milling was evaluated by X-ray diffraction. It was found that the paramagnetic Cr0.8Ni0.2 phase with bcc structure appears for 12 h of milling.