Effect of Doping different Percentages of Lithium Fluoride on Some Optical Characteristics of Poly-Methyl Methacrylate Polymer

This study implements the optical characteristics of Poly-Methyl methacrylate (PMMA) polymer before and after doping different percentages of Lithium Fluoride (LiF). Where the specimens were formulated as disk shape with diameter of (2.5 cm) and thickness of (0.148 cm) using Thermal pressing technology. The absorbance and reflectivity spectra were recorded in addition to their coefficients at range (300-1100) nm. Also, the study has included the determination of refraction and real and imaginary part of dielectric constant coefficients.

A Characteristic Study of Polylactic Acid/Organic Modified Montmorillonite (PLA/OMMT) Nanocomposite Materials after Hydrolyzing

In this study, the montmorillonite (MMT) clay was modified with NH4Cl, and then the structures were exfoliated or intercalated in a polylactic acid (PLA) matrix by a torque rheometer in the ratio of 0.5, 3.0, 5.0 and 8.0 wt%. X-ray diffraction (XRD) revealed that the organic modified-MMT(OMMT) was distributed successfully in the PLA matrix. After thermal pressing, the thermal stability of the mixed composites was measured by a TGA. The mixed composites were also blended with OMMT by a co-rotating twin screw extruder palletizing system, and then injected for the ASTM-D638 standard specimen by an injection machine for measuring the material strength by MTS. The experimental results showed that the mixture of organophilic clay and PLA would enhance the thermal stability. In the PLA mixed with 3 wt% OMMT nanocomposite, the TGA maximum decomposition temperature (Tmax) rose from 336.84 °C to 339.08 °C. In the PLA mixed with 5 wt% OMMT nanocomposite, the loss of temperature rose from 325.14 °C to 326.48 °C. In addition, the elongation rate increased from 4.46% to 10.19% with the maximum loading of 58 MPa. After the vibrating hydrolysis process, the PLA/OMMT nanocomposite was degraded through the measurement of differential scanning calorimetry (DSC) and its Tg, Tc, and Tm1 declined.

Effect of the areal weight of CNT-doped veils on CFRP electrical properties

The main goal of this work was the increasing electrical conductivity of carbon-epoxy composites due to implementation of thermoplastic nonwoven veils doped with carbon nanotubes into the composite structure. Nonwovens which differ in areal weight were produced by extrusion of fibers and their thermal pressing. Laminates were fabricated using an out-of-autoclave method and nonwovens were incorporated between each layer of carbon-epoxy unidirectional prepreg. The applied conductive nonwovens improved surface and volume electrical conductivity of carbon fibre reinforced polymer in all directions. Microstructure observations proved a very high quality of the fabricated composites. The implementation of nonwovens affected the crack propagation under loading.

STABILIZATION OF POLYETHYLENE BY NATURAL FILLERS AND THEIR EXTRACTS

The possibility of using natural fillers, as well as their extracts as antioxidant additives for polyethylene, was studied. Dried and shredded buckwheat husk sowing (Fagopyrum esculentum), carposome of crab-of-the-woods (Laetiporus sulphureus), carposome of chaga mushroom (Inonotus obliquus), thallus of lichen of oakmoss (Everonia prunastri) were used as natural fillers. Polymer films were made from mixtures of powders of low-pressure polyethylene and natural fillers (the first type of samples) or from a mixture of polyethylene powder and an extract of natural fillers (the second type of samples) by thermal pressing. The degree of oxidation of polyethylene films was controlled by IR spectroscopy. The paper shows that the stabilization of the polyethylene structure proved to be the most effective when used as an additive to the polymer of an extract of the oakmoss (Evernia prunastri). The result is attributed to the presence of secondary lichen metabolites in the extract. The introduction of dry residues of natural fillers proved to be ineffective for polymer stabilization.

Adhesive strength in a high voltage mica insulation system

The problem of maintaining a monolithic high-voltage mica insulation made by the Resin Rich technology for windings of electrical machines and conductors is considered. The violation of solidity like delaminations and peeling off from conductor can happen both during the process of manufacturing and during exploitation of constructions. The possibility of breaking the solidity is directly related to the magnitude of adhesion strength. Design and manufacturing technology of samples in laboratory and industrial conditions to determine the adhesion strength were developed. Adhesive strength is determined by the method of shear and tensile test method between insulation layers and in system of metal- mica insulation.The created method for the manufacture of samples made it possible to test samples with various designs of adhesive contact, materials of adhesive contact and technological parameters of the pressing process. The adhesion strength depends on the parameters of the thermal pressing process and the degree of curing of the binder in the initial resin rich tape. Adhesive contact of mica insulation to metal through fiberglass is more durable than through film

Оптические свойства полиэтилена, наполненного нанокристаллитами Bi-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-

Composite mixtures with various component concentrations are fabricated by the thermal pressing of low-density polyethylene and Bi_2Te_3 in the powder-like state with a nanocrystal size of ~50 nm. These samples preliminarily characterized by X-ray diffractometry and Raman spectroscopy are investigated by spectroscopic ellipsometry in a photon energy range of 1–6 eV. The dielectric functions for composites with a nominal Bi_2Te_3 weight concentration of 5, 10, 30, 40, 50, 60, and 70% are calculated based on the measured optical constants of polyethylene and the Bi_2Te_3 crystal in the approximation of the Bruggeman effective medium. The analysis of depolarization features of reflected light makes it possible to establish the actual inhomogeneity of the composite samples under study caused by the clusterization of nanocrystallites with an increase in the Bi_2Te_3 weight concentration in polyethylene and propose the most reliable optical model of the formed composites.

Thermal pressing of a metal-grid transparent electrode into a plastic substrate for flexible electronic devices

A flexible transparent electrode is prepared by thermal pressing of a metal-grid into a plastic substrate. The electro-mechanical reliability of the MGETEs is confirmed by the electrical performance of flexible organic solar cells on the MGETEs.