Advanced Materials Research Vols. 1025-1026

Abstract: Little research was done to investigate possible utilization of irradiated materials after the end of their lifetime. This research paper deals with the possible utilization of irradiated high-density polyethylene (HDPEx) after its service life. Irradiated HDPE was used as filler into the virgin low-density polyethylene (LDPE). Three material combinations were investigated (powder/powder, granules/powder and granules/grit) and influence of the filler on optical behavior was measured. Terahertz spectroscopy at wide range of frequencies was used for refractive index determination. According to measured data there is significant influence by the amount of the filler. Moreover influence of particle size was also observed. All three combinations have similar curve courses; however the most consistent results were achieved at the powder/powder combination. Behavior of virgin LDPE and virgin HDPE is in correlation with previous findings.

Abstract: This article deals with the influence of different doses of Beta radiation on nanomechanical properties of High-density polyethylene (HDPE). These nanomechanical properties were measured by the Depth Sensing Indentation - DSI method on samples which were non-irradiated and irradiated by different doses of the β - radiation. The highest values of nanomechanical properties were reached at radiation dose of 99 kGy, when the nanohardness values increased by about 23%. The purpose of the article is to consider to what extent the irradiation process influences the resulting nanomechanical properties measured by the Depth Sensing Indentation method.

Abstract: This article studies creep of a radiation cross linked HDPE polymer material. It describes a process of production of test samples, which are then radiation cross linked in six doses of radiation. These samples are tested for creep resistance at elevated temperatures on a machine of custom design that will provide sufficient information about a suitable use for the material and to find an optimal dose to achieve minimal stretching. [1-3]

Abstract: This work aimed to study the feasibility of using castor oil-based polyurethane (PU) resin, and rubberwood for the production of particleboards. Multilayer panels were produced using particles taken from RRIM 600 and GT1 clones of Hevea brasiliensis trees. Urea-formaldehyde (UF) and PU were used for bonding the particles. Physico-mechanical characterization was done according to the specifications of the European standards for wood-based panels. The average results were compared to values pre-established by the EN 312/2003 technical standard as well as between the above mentioned treatments. The results indicated that the use of PU and rubberwood has a great potential for particleboards production. The use of PU favors the production of boards with improved physical-mechanical characteristics.

Abstract: This study evaluates the machinability of titanium alloy, Ti6Al4V in terms of tool-chip interface temperature, cutting forces and tool stresses by varying rake angle of PCD insert and compares the results with TiAlN coated carbide inserted end mill using finite element numerical simulations. It has been found that tool rake angle has significant effect and behaves differently for different evaluation parameters and also shows different behavior for two different cutting material inserts. It reduces cutting forces with every positive angle geometry, about 50% reduction is observed for both cutting tool materials for a change in angle from-7° to 34°, but for tool-chip interface temperature, 15% reduction has been observed when angle is changed from-7° to 15° but it starts rising again when angle is increased to 34° for PCD insert, but for TiAlN coated carbide insert a continuous drop of about 20% has been observed. For tool stresses tool rake angle has different effect. The stresses remains almost unchanged when angle is changed from-7° to 15° but increased by almost 20% when angle is changed to 34° for both insert materials. Results also have shown that PCD insert due to its excellent thermal conductivity and strength at elevated temperatures dissipates most of the heat into the chip and has almost half temperature near the tool edge as compared to TiAlN coated carbide insert and thus can be used for machining of Ti6Al4V alloy at much higher cutting speeds than TiAlN coated carbide insert with positive rake angle geometries (around 15°).

Abstract: The present study was designed to investigate the effects of hydrolyzed fish collagen (HFC) on the cytokine production of lipopolysaccharide (LPS)-induced human umbilical vein endothelial cells (HUVECs). The in vitro inflammation model was established using LPS-induced HUVECs.The cell viability of HUVECs and the secretion level of inflammatory cytokines,IL-6, IL-8, and TNF-α from LPS-treated HUVECs exposed to HFC were determined respectively using MTT and ELISA assays. Our results indicate that HFC promoted HUVECs proliferation, and significantly reduced IL-6, IL-8, and TNF-α production in LPS-stimulated HUVECs. It suggested that HFC had a prominent anti-inflammatory property, HFC could be considered as a promising candidate for anti-inflammatory wound dressing.

Abstract: Silica gel is the chemical substance that has many good advantages such as absorbed moisture, porosity, small diameter, high surface area, and lightweight. It was synthesized by using rice husk ash via sol – gel heating in the microwave technique. The objectives in this work compose of synthesis silica gel by using the microwave technique before characterizatization. This raw material was archived from rice husk ash, obtained from agricultural waste. The silica gel, synthesized by conventional method (CVM) and commercial silica gel (COM), was also studied for comparison purposes. The results showed that successfully synthesized the silica gel by sol - gel technique using microwave. The XRD pattern of silica gel enhanced from this method was not sinificantly different as compared with CVM and COM methods. And the physical properties of this technique could be debated. The particle size of silca gel was determined by zetasizer and it was approxmately 50-70 nm. The pore size diameter, pore volume, and specific surface area of silica gel were calculated by Flowsorb II and a Quantachrome Autosorp-1. The pore size diameter, pore volume, and specific surface area of silica gel are 10-30 nm, 0.7-1.0 cm³/g, and 400-700 m²/g, respectively. Consequently, this work is considered to be the waste to make useful, and a great way to save energy and time in the silica gel synthesis.

Abstract: Glycolyzed polylactic acid (GPLA)-cured epoxidized natural rubber (ENR) is developed for use as a toughening agent for PLA resin. GPLA is obtained from chemical recycling of PLA resin by a glycolysis reaction. GPLA-cured ENR is then prepared by the crosslinking reaction of ENR with GPLA in an internal mixer. Chemical structures of the cured products are characterized by solvent fractionation and thermogravimetric analysis (TGA). The cured ENR products are blended with PLA resin, by varying the cured ENR contents from 5 to 15% wt. Mechanical properties of the blends, and their toughening mechanisms are examined. The cured ENR materials has higher efficiency in improving toughness of PLA resin, compared to uncured ENR, likely due to their rubbery network nature and higher compatibility with the PLA matrix. The incorporation of 5% wt. GPLA-cured ENR also improves elongation at break with no adverse effect on tensile strength and modulus of PLA.

Abstract: In this work, a series of samples of Mo (Si_1-xAl_x)₂ (X =0, 0.10,0.20,0.30,0.40) were prepared by self-propagating high-temperature synthesis (SHS). The influence of the addition of Al on the structures and the micrographs of the final compounds were investigated. X-ray diffraction pattern characterization (XRD) and scanning electron microscopy (SEM) were used to characterize the obtained products. It was found that, the reactions between Mo and Si could be promoted with introducing Al during the SHS process. The high temperature β-MoSi₂ phase with hexagonal structure (C40) was obtained and the peaks of the C40 phase shifted towards a higher d value with increasing aluminum substitution. The substitution of Al could reach to 40%. The morphology of the final products was similar with that of the raw Mo powders, which was independent of Al contents.

Abstract: Ni-base Inconel 625 alloys with a composition of 58.9Ni-22Cr-9Mo-5Fe 3.5Nb-0.4Si-0.4Mn-0.4Al-0.4Ti (wt.%) corroded at 600, 700 and 800 °C for up to 30 h in 1 atm of N₂/H₂O/H₂S-mixed gases. They corroded fast owing to the formation of sulfides and the presence of hydrogen and water vapor in the gas. Triple layered scales formed. Nickel corroded to NiS to form the outer NiS layer, where Fe was dissolved. Chromium corroded to Cr-sulfides to form the middle layer. Other alloying elements such as Mo, Nb, Si, Mn, Al, and Ti corroded to form the inner layer that consisted primarily of intermixed sulfides and oxides. Since sulfides were present throughout the scale and hydrogen made the scale porous and fragile, Inconel 625 was nonprotective during high-temperature corrosion in N₂/H₂O/H₂S gases.