Research Advances in Oil Tanning Technology

The conventional process of chamois leather manufacturing for industrial applications utilizes fish oil which contains substantial amounts of pentadienoic fatty acid. The applications of chamois leathers include cleaning polished surfaces, manufacture of gloves and orthopedic uses. However, due to fish oil’s strong odor and high cost, considerable efforts have been made to counter these challenges. Esterification of fish oil has been used as a strategy to address the problem of odor and water absorption but this cannot solve the issue of cost. Oils from plant sources such as linseed, rubber, jatropha, castor and sunflower have been investigated as potential tanning substitutes for fish oil. Linseed has been found to produce chamois leather with mild odor and water absorption characteristics close to those of fish oil compared to other oils obtained from plant sources. Oil from goat fleshing has also been investigated in chamois leather production and has been found to produce chamois leather whose odor compares with that of linseed oil tanned leather. If these tanning oil alternatives are combined with other research advances in chamois leather production such as glutaraldehyde pre-tanning and oxidation using hydrogen peroxide or through ozonation, then the issue of cost, odor and long oxidation period can be resolved.

Nanostructured Hematite Prepared by Thermal Oxidation of Iron

This paper reports on the synthesis of iron oxide nanowires using thermal oxidation of iron. The α-Fe2O3 (hematite) and Fe3O4 (magnetite) were successfully formed using this method. The morphological observation was done through the FESEM, while the XRD, EDX and Raman spectroscopy were used to determine the physical and structural properties of the produced nanostructures. It was found that the peaks intensities relative to the hematite, increased with the extent of oxidation period. The growth and final morphology of hematite was significantly controlled by the heating duration. A surface diffusion mechanism for nano-hematite growth was then proposed to account for the growth phenomena of this nanostructured formation.

Crack Disappearance by High-Temperature Oxidation of Alumina Toughened by Ni Nano-Particles

Crack disappearance by high-temperature oxidation was studied in alumina (Al2O3) composites toughened by Ni nanoparticles. This process is performed in air at temperature ranging from 1000 to 1300°C for 1 to 48 h. The results showed that crack disappearance depends on both annealing temperature and time. Complete crack disappearance in this composite was confirmed at lower temperatures for long oxidation period, 1100oC for 48 h, and higher temperature for shorter time, 1300oC for 1 h in air. The crack disappearance mechanism was explained on the basis of the formation of NiAl2O4 spinel on sample surfaces produced by the oxidation reaction during the heat treatment.

FT-IR Imaging of the Thermal Oxidation of Polyisoprene (PI) Rubber at High Temperature

The thermal aging of PI rubber in hot air (140 °C) has been studied using the FT-IR imaging technique. From the analysis of the FT-IR images of the absorbance of the carbonyl (C=O) groups, it was found that the most significant thermal oxidation occurred at the surface of the rubber with a decreasing gradient of oxidation from the surface to the interior of the system. The hydroxyl (OH) groups followed the same pattern as the carbonyl groups. The C=C double bonds decreased from the interior of rubber to the surface, demonstrating the existence of a highly cross-linked oxidative coating, which functions as a protective layer blocking further invasion of the oxygen. The depth of the oxidation coating was constant at approximately 160 μm and the most significant oxidation layer was ∼90 μm after 10 h oxidation. Based on the FT-IR images as a function of time, the oxidation process is interpreted and classified in terms of four time periods: an induction period, a rapid oxidation period, a slow oxidation period, and a diffusion-forbidden period. Both the thickness of the oxidation coating and the degree of oxidation at different depths show that the oxidation process is auto-catalytic and the induction period is approximately two hours.

Photoluminescence Study of Self-Limiting Oxidation in Nanocrystalline Silicon Quantum Dots

ABSTRACTWe have studied photoluminescence (PL) of surface oxidized nanocrystalline silicon quantum dots (QDs) for various oxidation periods and temperatures. With increasing oxidation period, the surface oxide grows and the Si QD core shrinks initially, then retardation of the oxidation process occurs which is ascribed to compressive stress at the interface between Si QD core and oxide. Upon oxidation, the PL spectrum peak shifts toward the shorter wavelength side followed by retardation of the blueshift or even manifestation of the redshift. The origin of PL is due to the localized excitons at the interface between Si QD core and oxide or amorphous SiOx (a-SiOx) formed at the interface. The blueshift is associated with the increased quantum con.nement or increased bandgap of a-SiOx. The redshift is due to the stress e.ect of the bandgap of Si QD core or a-SiOx. We have successfully confirmed the effect of compressive stress associated with the self-limiting oxidation by PL measurement.