Papers by Keyword: Sepiolite

Abstract: Gamma irradiation is a particularly effective method for inducing crosslinking, which leads to improved composite characteristics. The effects of gamma irradiation on swelling percentage, flammability and morphological analysis were investigated. Ethylene Propylene Diene Monomer (EPDM) rubber composites were prepared with various amounts from 10-60 phr (part per hundred part of rubber) of the sepiolite particles using a two-roll mill machine. The composites were subjected to 50 kGy of gamma irradiation and compared with unirradiated composites. The results demonstrate a reduced in swelling percentage at all sepiolite loadings. The crosslinks of rubber chains into sepiolite/EPDM composites generated by gamma rays resulted in improvements in the swelling resistance. The irradiation composites, however showed lower flammability resistance to the non-irradiated composites.

Abstract: The results of the studies aimed at increasing the water resistance of the pressed building materials based on gypsum and magnesia binders due to their modification with active dispersed fillers from secondary resources are presented. The gypsum binder modification was carried out by the joint introduction of carbonate-containing sludge from it into the chemical treatment of thermal power plants and monoammonium phosphate, and of magnesia cement - silica fume and finely ground burnt mines. Physical and mechanical characteristics of the materials’ control samples were determined according to the standards and generally accepted methods. The increase in water resistance of the pressed modified composites was evaluated by changing the softening coefficient. It is shown that when using gypsum binders, an increase in the water resistance of products based on them can be achieved by changing the structure formation of the pressed material and the formation on the elements’ surface of its fine-crystalline structure of the sparingly soluble calcium phosphates’ screening protective films. The increase in water resistance of pressed products made of modified magnesia binders is explained by the appearance of insoluble hydro silicates, hydro aluminates and hydro aluminosilicates of magnesium, in the structure of the hardened artificial stone as well as the formation of a complex combined structure containing coagulation, condensation and crystallization phases. The technical characteristics of the materials obtained are sufficient for their use, in particular, in the building envelope. The possibility of replacing a significant amount of binders with secondary resources has been identified. This allows not only to increase the water resistance of the pressed products on the basis of the proposed modified binders, but also to reduce their cost, as well as free up the land allocated for dumps.

Abstract: Al³⁺-modified sepiolite was synthesized through hydrothermal treatment of acidified sepiolite using sodium aluminate as a modifier. The structure and surface properties of the modified sepiolite were characterized by XRD, FTIR, NMR, and Zeta potentials. The XRD and FTIR results demonstrated that Al³⁺ ions were introduced into the sepiolite lattice. ²⁹SiNMR of the sepiolite ore showed that Si atoms had three configurations with chemical shifts of -98.4, -95.2, and -92.5 ppm with the atomic ratio of 1.39: 1.43: 1, which was assigned to the center silicon, edge silicon, and near-edged silicon atoms, respectively. For the as-prepared Al³⁺-modified sepiolite, the signal intensity of the edge silicon atoms decreased and shifted from -95.2 ppm to -94.5 ppm. Moreover, a new chemical shift of - 87.4ppm belonging to Q¹ structure appeared. The ratio of four configurations of silicon atoms was 1.43: 1: 1.53: 1.04. ²⁷AlNMR of Al³⁺-modified sepiolite showed that Al atoms have two configurations corresponding to the tetra-coordination and octahedral coordination, respectively. The results of NMR revealed that the sepiolite was modified by substitution of Si atoms in the framework and Mg atoms in the interlayer, resulting in a less negative charge on the surface of Al³⁺-modified sepiolite.

Abstract: The effects of sepiolite nanofiller addition and irradiation modification on the tensile properties of epoxidized natural rubber (ENR-50)/ehylene vinyl acetate (EVA)/Sepiolite nanocomposites were investigated. The ENR-50/EVA/Sepiolite was blended by mixing in a Brabender Plastigraph at 120 °C. The samples were irradiated by using electron beam at a dose range of 50 to 200 kGy. The effect on the tensile properties and morphology were investigated as a function of sepiolite content and irradiation dose. Electron beam radiation produced an irradiation-induced crosslinking and further enhanced mechanical properties of the nanocomposites. The tensile properties of irradiated ENR-50/EVA blend were improved by the addition of sepiolite at 4 phr.

Abstract: Biopolymer composites are required to enhance their mechanical properties and heat resistance for the industrial applications. Especially, the addition of nanoparticles in biopolymers can give various functionalities such as electrical, thermal and mechanical properties. In this study, the nanoparticles having functional characteristics were used to enhance heat resistance, tensile properties, and electrical conductivity of PBTG biofilms. Changes in tensile, crystalline and thermal properties of PBTG films with different additives (carbon black, sepiolite, zinc oxide, MWCNT) were investigated by the tensile tester and the instrument of XRD, DSC and TGA. As the results, Electrical conductivity of the biofilms was improved up to 10^-5S/cm by adding MWCNT. And tensile modulus of PBTG biofilms with MWCNT was 1.37 times higher than the pure PBTG film. But their heat-resistance characteristics were not significantly affected by adding nanoparticles.

Abstract: H-Sep samples were taken from treating sepiolite with HCl solution. Cu/H-Sep samples were prepared by the incipient wetness impregnation method. The samples were characterized using XRF, XRD, and XPS techniques, and their catalytic activities were performed by the SCR of NO with propylene. The results show that the Cu/H-Sep catalyst exhibited the high performance in the C₃H₆-SCR of NO. After investigation by XRD and H₂-TPR, the result showed that there are Cu²⁺/Cu⁺ redox species as a reaction activity center over Cu/H-Sep.

Abstract: This study was conducted in order to develop the new polymer nanocomposites. In this case, sepiolite was incorporated into Polyamide 6 (PA6) / Ethylene vinyl acetate (EVA) blend. The main aim of this research is to examine the effect of sepiolite concentration on the properties of PA6/EVA/sepiolite nanocomposite. The variations of sepiolite (2 – 10 phr) were added into PA6/EVA blend at the ratio of 80/20 wt%. The nanocomposites were prepared using twin screw extruder and injection moulding. Mechanical properties of PA6/EVA/sepiolite nanocomposite were analyzed by tensile testing and it was revealed that there is no change in stiffness and decrease in strength with more sepiolite content. Meanwhile, the morphology of materials was characterized by field emission scanning electron microscopy (FESEM). The morphology revealed that, the dispersion of sepiolite nanofiller seems to be good and the EVA domain size and distribution was effected by sepiolite content.

Abstract: Cu/Na-Sep samples were prepared by the incipient wetness impregnation method. These catalysts were characterized by means of XRF, XRD, and XPS techniques, and their catalytic activities were performed by the SCR of NO with propylene. The results show that the Cu/Na-Sep catalyst exhibited the high performance in the C₃H₆-SCR of NO. After investigation by XRD and XPS, the result showed that there are Cu²⁺/Cu⁺ redox species as a reaction activity center over Cu/Na-Sep.

Abstract: Cu/H-Sep and Cu-Fe/H-Sep samples were prepared by the incipient wetness impregnation method. These catalysts were characterized by means of XRF, XRD, BET, XPS, and H₂-TPR techniques, and their catalytic activities were performed by the SCR of NO with propylene. The results show that the Cu-Fe/H-Sep catalyst exhibited the best performance in the C₃H₆-SCR of NO. After investigation by H₂-TPR, XRD and XPS, the result showed that the higher reducibility, more amount of isolated Cu²⁺, higher dispersion of copper species, and stronger metal-support interaction were responsible for the excellent catalytic activity of Cu-Fe/H-Sep.

Abstract: A biodegradable poly-lactic acid (PLA)/Sepiolite nanocomposite films were prepared by the thermo-compression and solvent-casting methods, and barrier properties (water-vapor and gas barrier) were evaluated. By introducing sepiolite into PLA, the properties of nanocomposite films improved until a certain amount (1.5% wt). By increasing sepiolite loading, nanoparticles tented to agglomerate and gas permeability (GP) decreased. According to the results, the nanocomposite films prepared by the thermo-compression method were more brittle but strong due to the formation of more crystals; while solvent-casted films were more ductile due to the presence of solvent, which may act as a plasticizer, as evidenced by the results of the GP.