Effect of Rare Earth Ions on the Properties of Composites Composed of Ethylene Vinyl Acetate Copolymer and Layered Double Hydroxides

BACKGROUND: The study on the rare earth (RE)-doped layered double hydroxides (LDHs) has received considerable attention due to their potential applications in catalysts. However, the use of RE-doped LDHs as polymer halogen-free flame retardants was seldom investigated. Furthermore, the effect of rare earth elements on the hydrophobicity of LDHs materials and the compatibility of LDHs/polymer composite has seldom been reported. METHODOLOGY/PRINCIPAL FINDINGS: The stearate sodium surface modified Ni-containing LDHs and RE-doped Ni-containing LDHs were rapidly synthesized by a coprecipitation method coupled with the microwave hydrothermal treatment. The influences of trace amounts of rare earth ions La, Ce and Nd on the amount of water molecules, the crystallinity, the morphology, the hydrophobicity of modified Ni-containing LDHs and the adsorption of modifier in the surface of LDHs were investigated by TGA, XRD, TEM, contact angle and IR, respectively. Moreover, the effects of the rare earth ions on the interfacial compatibility, the flame retardancy and the mechanical properties of ethylene vinyl acetate copolymer (EVA)/LDHs composites were also explored in detail. CONCLUSIONS/SIGNIFICANCE: S-Ni₀.₁MgAl-La displayed more uniform dispersion and better interfacial compatibility in EVA matrix compared with other LDHs. Furthermore, the S-Ni₀.₁MgAl-La/EVA composite showed the best fire retardancy and mechanical properties in all composites

Effect of Zinc Application Methods on Nutrition Uptake in Cotton

This study was carried out to determine the effect of different zinc application methods on cotton plant nutrient uptake and nutrition content in the soil. The study was conducted at Siirt University Faculty of Agriculture Department of Field Crops experimental area as a randomized complete block design with four replications. Seven different zinc applications were performed (Control, To Soil 200 g da-1, To Soil 400 g da-1, Soil + Leaves at Pre-Squaring Stage, Pre-Squaring Stage + Initial Flowering Stage to Leaves, Pre-Squaring Stage + Pre Flowering Stage + Flowering Stage to Leaves, Pre-Flowering Stage + Flowering Stage to Leaves). According to the results of leaf analysis, it was determined that there were non-significant differences in terms of N, K, Ca, Na, Mg, Fe, Zn, Mn, and Cu content, but soil analysis after harvest showed that N, K, Ca, Na, Mg and Cu content were affected from different zinc treatments, however, P, Fe, Zn, Mn were not affected from applications. It has been observed that the highest N, P, K, Ca, and Na value in the soil was obtained from zinc applications to the soil + pre- squaring stage to leaf, and the highest Mg and Fe value in the soil was obtained from control. Although there were no significant differences detected between the zinc applications in terms of leaf analysis, it was observed that the highest K, Ca, Na, Mg, Fe, Mn, and Cu values were obtained from the zinc application of 200 g da-1 to the soil. In the study, it was observed that the highest zinc values in the leaf and soil were obtained from the foliar application of zinc applied before squaring and beginning of flowering. This application can be recommended to increase the zinc content in the soil and leaves

Thermophysical properties of ethylene-vinyl acetate copolymer (EVA) filled with wollastonite fibers coated by silver

A new type of thermally conductive fibers based on silver coated wollastonite was prepared and characterized. The fibers were used for the preparation of elastic, highly thermally conductive polymeric composites based on ethylene-vinylacetate copolymer (EVA). It was shown that silver coated fibers significantly improved the thermal conductivity of composites despite the low silver volume content. The experimental results were discussed and compared to various theoretical models. The specific heat and the specific density of the composites were also characterized and reported. (c) 2008 Elsevier Ltd. All rights reserved

Thermophysical and Electrical Properties of Nanocomposites Based on Ethylene-Vinylacetate Copolymer (EVA) Filled with Expanded and Unexpanded Graphite

Over the last few years, conducting polymer/graphite nanocomposites have attracted considerable interest because of their exceptional electrical, thermal, and mechanical properties. Polymeric nanocomposites prepared from high aspect ratio layered graphite nanofillers achieve significant improvements in thermophysical and electrical properties at low filler concentrations, compared to conventional composites, without a significant increase in density. In this work, various aspects of the electrical and thermophysical behavior of nanocomposites are presented based on the ethylene-vinylacetate matrix filled with nanostructured expanded graphite and standard, (nano)/micro-sized graphite

Mechanical anisotropy in unidirectional glass fabric reinforced oligomeric siloxane modified polyester composites

In this study, the effect of incorporation of oligomeric siloxane into unsaturated polyester on mechanical behavior of unidirectional glass fiber/polyester composites has been investigated by means of tensile, flexural and short beam shear tests. The amount of oligomeric siloxane added into unsaturated polyester was in the range 1-3 % by weight of the glass fabrics. Mechanical tests were conducted at different angles (0 degrees, 45 degrees, and 90 degrees) with respect to fiber direction. The higher siloxane content exhibited a tendency to have greater tensile, flexural and interlaminar shear strength values in machine direction, bias direction and cross direction. From Scanning electron microscopy images, the presence of polyester particles on the unidirectional glass fiber surface confirmed better adhesion

Electrical, mechanical and adhesive properties of ethylene-vinyl acetate copolymer (EVA) filled with wollastonite fibers coated by silver

New type of electrically conductive polymeric composites was prepared using ethylenevinylacetate (EVA) matrix filled with silver-coated wollastonite (W-Ag) fibers. The electrical, mechanical and adhesive properties of the composites are reported in this paper. The electrical percolation threshold was found about 8 vol.% and the highly electrical conductivity value (1.8 x 10(5) S m(-1)) is reached for 29 vol.% of filler fraction. The mechanical and adhesive properties of these composites were also discussed and correlated with some models. (c) 2008 Elsevier Ltd. All rights reserved