Mechanical Study of Some Polystyrene composites modified with adding inorganic fillers

Polystyrene-Zinc oxide microcomposites have been prepared for Mechanical study. The Zinc oxide micro particles were added to polystyrene by different concentrations that are (3, 5, and 7) by weight percent of the pure polymeric matrix. Solution casting method is used for preparing such composites. Different Mechanical properties of (PS-ZnO) microcomposites have been measured. Stress strain Curve is investigated for both pure Polystyrene and its composites with zinc oxide. The results showed that the Tensile Strength varies with the increase of ZnO in a specific way. Elongation at break of (PS-ZnO) micro composites increase with increase the content of (ZnO). An explanation of such behavior in tensile strength as well as Elongation at break has been discussed.

Effect of NaBr on the Structural, Thermal and Mechanical Properties of HPMC:NaBr Composite Films

The hydroxypropyl methylcellulose (HPMC):sodium bromide (NaBr) composite films were prepared using different concentrations by solution casting method. The crystalline percentage of the pure HPMC was reduced from 74% to 60% upon the incorporation of 0.7 wt.% of NaBr salt, which suggests that the NaBr salt disrupted the host polymer crystalline phase. The two-phase microstructure in the morphological images reflects the phase separation at different concentrations of dopant. The functional studies revealed the considerable variation of intensity and the shift of peaks due to the action of NaBr in the host polymer matrix. The HPMC showed a large increase in the glass transition temperature (Tg) from 65 ºC to 86 ºC and simultaneously reduction in the weight percent loss was observed. The mechanical analysis revealed that the added dopant has a significant effect on the mechanical properties of HPMC.

Assisting Liquid Phase Sintering of Pure Aluminum (Al) by the Tin Addition

In the present study, the addition of tin (Sn) to the pure Al system was done, and its effects on the morphology, density, and compressive yield strength of pure Al were analyzed systematically. In this context, the morphology of sintered Al revealed enhanced wettability and sintering response between Al particles with increased Sn content. Moreover, physical characteristics of sintered Al alloys demonstrated oxidation phenomenon (black color specimen) with the lowest Sn content of 1.5 weight percent (wt.%), in which a higher Sn content of 2 and 2.5 wt.% produced silver color specimens, implying a reduction in oxidation. Additionally, densification of sintered Al alloys was greatly promoted with increased Sn contents, suggesting effective wetting as confirmed by the previous morphological observations. Similarly, the compressive yield strength of sintered Al alloys improved with increased Sn content which might be due to the enhanced inter-particle contacts between Al particles and sufficient wetting by molten Sn. Based on the results obtained, the introduction of Sn powder at various contents improved the sintering response of pure Al powder by providing sufficient liquid-phase sintering. Therefore, the sintered Al alloys had enhanced the morphological, densification, physical characteristics, and compressive yield strength.

Research on Mechanical and Electrical Properties of Cu-Ag Alloys Designed for the Construction of High Magnetic Field Generators

The individual sections, wiring and construction of electromagnet windings responsible for strong magnetic field impulses may be one application for hypoeutectic Cu-Ag alloys. High electrical properties and mechanical properties (tensile strength, yield strength, impact strength) as well as high heat, fatigue and rheological resistance are required for these kinds of applications due to the unique nature of such operations (strong vibrations of high frequency and amplitude resulting from Lorenz forces and the possibility of significant and rapid heating from Jule’s heat). The limited solubility of copper and silver in the solid state enables the effective modification of the alloys’ microstructure through heat treatment and further shaping of their high mechanical and electrical properties via cold plastic working. The article presents the manufacturing of Cu-Ag alloys with the weight percent of Ag between 3 and 7 using the continuous casting process along with research on the physicochemical, mechanical and electrical properties of the obtained casts. The research on the amount of plastic deformation and its influence on the wire drawing process and the mechanical and electrical properties of the wires is also discussed. The temperature coefficients of resistance were defined in order to determine the temperature influence on the electrical resistance changes dynamics. The microstructural analysis was carried out in the as-cast state. The preliminary research conducted indicates that the obtained Cu-Ag alloys in the as-cast state exhibit a set of high mechanical and electrical properties. The prospective next stage of research includes the selection of favourable heat treatment parameters which would provide optimally modified microstructure of the alloys, as well as determining the deformation coefficients allowing for further increases in the mechanical and electrical properties.

Investigating optimal region for thermal and electrical properties of epoxy nanocomposites under high frequencies and temperatures

This research investigates the optimal region to achieve balanced thermal and electrical insulation properties of epoxy (EP) under high frequency (HF) and high temperature (HT) via integration of surface-modified hexagonal boron nitride (h-BN) nanoparticles. The effects of nanoparticle content and high temperature on various electrical (DC, AC, and high frequency) and thermal properties of EP are investigated. It is found that the nano h-BN addition enhances thermal performance and weakens electrical insulation properties. On the other side, under HF and HT stress, the presence of h-BN nanoparticles significantly improves the electrical performance of BN/EP nanocomposites. The EP has superior insulation properties at low temperature and low frequency, whereas the BN/EP nanocomposites exhibit better insulation performance than EP under HF and HT. The factors such as homogeneous nanoparticle dispersion in EP, enhanced thermal conductivity, nanoparticle surface modification, weight percent of nanoparticles, the mismatch between the relative permittivity of EP and nano h-BN, and the presence of voids in nanocomposites play the crucial role. The optimal nanoparticle content and homogenous dispersion can produce suitable EP composites for the high frequency and high temperature environment, particularly solid-state transformer applications.

Nanoprecipitation of Biocompatible Poly(malic acid) Derivative, Its Ability to Encapsulate a Molecular Photothermal Agent and Photothermal Properties of the Resulting Nanoparticles

Biocompatible nanoparticles (NPs) of hydrophobic poly(benzyl malate) (PMLABe) were prepared by nanoprecipitation. The influence of nanoprecipitation parameters (initial PMLABe, addition rate, organic solvent/water ratio and stirring speed) were studied to optimize the resulting formulations in terms of hydrodynamic diameter (Dh) and dispersity (PDI). PMLABe NPs with a Dh of 160 nm and a PDI of 0.11 were isolated using the optimized nanoprecipitation conditions. A hydrophobic near infra-red (NIR) photothermally active nickel-bis(dithiolene) complex (Ni8C12) was then encapsulated into PMLABe NPs using the optimized nanoprecipitation conditions. The size and encapsulation efficiency of the NPs were measured, revealing that up to 50 weight percent (wt%) of Ni8C12 complex can efficiently be encapsulated with a slight increase in Dh of the corresponding Ni8C12-loaded NPs. Moreover, we have shown that NP encapsulating Ni8C12 were stable under storage conditions (4 °C) for at least 10 days. Finally, the photothermal properties of Ni8C12-loaded NPs were evaluated and a high photothermal efficiency (62.7 ± 6.0%) waswas measured with NPs incorporating 10 wt% of the Ni8C12 complex.

Experimental studies on interlaminar shear strength and dynamic mechanical analysis of luffa fiber epoxy composites with nano PbO addition

In the present study, the significance of nanofiller lead oxide (PbO) on the dynamic mechanical analysis (DMA) and interlaminar shear strength (ILSS) performance of luffa fiber–reinforced epoxy composites was investigated. The epoxy matrix was altered with nanofiller PbO of different weight percent through a mechanical stirring process. The PbO-added luffa fiber epoxy composites were made through hand layup preceded by the compression molding method. The prepared composite samples were investigated for ILSS and DMA. The test results lead to the inference that the 1.25 wt% PbO nanofiller–added composite samples attained 25%, 17%, and 55% of higher loss modulus, storage modulus, and ILSS, respectively, as compared with the other prepared samples. The morphological investigation was conducted on the fractured surface of the interlaminar tested samples. The micrographic images show the bonding nature of the luffa fiber with the epoxy matrix, fiber breakage, and fiber pullouts. The characterization studies such as FTIR, XRD, and EDX were conducted on the fabricated composite samples. The XRD studies show that the rise in weight percent of the nanofiller PbO enhances the crystallinity of the composite samples. Moreover, the composite sample prepared with 1.25 wt% nanofiller PbO can be used to prepare low-cost roofing materials for sustainable housing projects.

Dynamic mechanical behavior of composite materials reinforced by graphene and huntite minerals

The aim of this study is to investigate the dynamic mechanical properties of composite materials reinforced by mineral experimentally. Graphene and huntite minerals were added to epoxy resin at different weight ratios (wt.-%) as 0.5 weight percent, 1 weight percent and 3 weight percent, to examine the effect of mineral types and percentages on the resulting dynamic mechanical properties. In addition, the effect of non-layered huntite unlike graphene, with a nano-sized grain structure, was investigated. Thus, glass transition temperature (Tg), storage modulus (E’), loss modulus (E”) and damping ratio (tan δ) values were determined and compared. Moreover, a tensile test was performed in order to explain the relation between stress and strain. It was seen that adding different minerals caused different results according to types and proportions. In general, adding minerals to the pure resin increased the storage modulus and loss modulus, whereas the damping ratio (tan δ) decreased compared to the pure resin.

Experimental evaluation and modelling of the boronizing kinetics of AISI H13 hot work tool steel

In the study for this contribution, the AISI H13 hot work steel was pack-boronized between 2 and 6 h of exposure time within the temperature range of 800 – 1000 °C. The boriding agent was composed of a powder mixture containing (in weight percent): 90 % of boron carbide (B4C) and 10 % of sodium tetrafluoroborate (NaBF4). The SEM observations showed a less pronounced jagged interface between the boronized layer and the transient zone. A double phase boride layer (FeB and Fe2B) was identified over the surface of AISI H13 steel with the presence of metallic borides inside this compound layer. The mean diffusion coefficient (MDC) method was applied to analyze the growth of iron borides (FeB and Fe2B) as compact layers over the surfaces of AISI H13 steel. The boron activation energies in the two iron borides were also assessed from the present kinetic approach by assuming the Arrhenius relationships. Afterwards, the kinetic model was checked experimentally by considering two extra boriding conditions (925 °C for 1 and 3 h). Finally, the predicted layer thicknesses are in accordance with experimental measurements.