There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Can nanoparticles really enhance thermal stability of polymers? Part I: An overview on thermal decomposition of addition polymers

The problem of environmental pollution is a global concern as it affects the entire ecosystem. There is a cyclic revolution of pollutants from industrial waste or anthropogenic sources into the environment, farmlands, plants, livestock and subsequently humans through the food chain. Most of the toxic metal cases in Africa and other developing nations are a result of industrialization coupled with poor effluent disposal and management. Due to widespread mining activities in South Africa, pollution is a common site with devastating consequences on the health of animals and humans likewise. In recent years, talks on toxic metal pollution had taken center stage in most scientific symposiums as a serious health concern. Very high levels of toxic metals have been reported in most parts of South African soils, plants, animals and water bodies due to pollution. Toxic metals such as Zinc (Zn), Lead (Pb), Aluminium (Al), Cadmium (Cd), Nickel (Ni), Iron (Fe), Manganese (Mn) and Arsenic (As) are major mining effluents from tailings which contaminate both the surface and underground water, soil and food, thus affecting biological function, endocrine systems and growth. Environmental toxicity in livestock is traceable to pesticides, agrochemicals and toxic metals. In this review, concerted efforts were made to condense the information contained in literature regarding toxic metal pollution and its implications in soil, water, plants, animals, marine life and human health.

https://www.mdpi.com/1660-4601/17/7/2204/pdf

Toxic Metal Implications on Agricultural Soils, Plants, Animals, Aquatic life and Human Health

Heavy Metals in the Environment: Origin, Interaction and Remediation, Heike B. Bradl (Ed.). Elsevier/Academic Press, London (2005), 269 pp

This work investigates the thermodynamics parameters and adsorption mechanism of Euphorbia heterophylla L. extract as a corrosion inhibitor for mild steel in 1.5 ​M HCl. The gravimetric method was used to determine the inhibition efficiency and corrosion rate. Relevant thermodynamic equations were employed to determine the activation energy, enthalpy change and entropy change. The adsorption isotherms were used to evaluate the Gibbs free energy change. Observation from the results of the study showed that the activation energy of an inhibited process was higher when compared with the uninhibited process. Also, the enthalpy change was positive and less than 100 ​KJ/mol threshold. The adsorption study showed that the data fit into the Langmuir, Flory-Huggins, El-Awary’s and Temkin isotherms but Flory-Hugins gave the best fit. The Gibb’s free energy change of adsorption was negative and less than the −20 ​KJ/mol threshold. As concluded from the results, the adsorption of Euphorbia heterophylla L. on mild steel in 1.5 ​M HCl medium is feasible, spontaneous and it occurred by physical adsorption according to Flory-Hugins isotherm model.

Thermodynamics and Adsorption Study of the Corrosion Inhibition of Mild Steel by Euphorbia heterophylla L. Extract in 1.5 M HCl

Corrosion and wear phenomenon has been responsible for the gradual deterioration of components in industrial plants. This deterioration of components results in loss of plant efficiency, total shutdown and aggressive damage in a number of industries. Hence, surface modification and coating technique with enhanced surface properties is desirable. The study was designed to investigate the enhancement in the corrosion, hardness and wear properties of Al-Sn binary coatings on AISI 1015 steel by laser alloying technique using ytterbium laser system (YLS). A laser power of 1000 W, scanning speeds of 0.6 and 0.8 m/min, and alloy compositions of Al-75Sn, Al-50Sn and Al-25Sn were used in this study. Decrease in Sn content from 75 to 25% at different laser processing conditions resulted in improved properties. The enhanced properties were obtained at 75Al-25Sn alloy at laser power of 1000 W and speeds of 0.6 and 0.8 m/min. At optimum composition and speed of 0.8 m/min, there was enhancement of 53.63% in microhardness. At scanning speed of 0.6 m/min, 75Al-25Sn alloy exhibited the highest polarization resistance, R
 p, (1.06 × 108 Ω cm2); lowest corrosion current density, I
 corr, (3.12 × 10−7 A/cm2); and lowest corrosion rate, C
 r, (0.00363 mm/year) in 3.65 wt% NaCl solution. In addendum, significant reduction in wear volume loss of 75Al-25Sn alloy at 0.8 m/min was attributed to excellent wear resistance performance due to metastable intermetallic phases. This research has established the enhanced surface properties of laser alloyed Al-Sn binary coatings on AISI steel for engineering applications.

Effects of rapid solidification on the microstructure and surface analyses of laser-deposited Al-Sn coatings on AISI 1015 steel

Thermal properties of poly(ethylene succinate) nanocomposite

The ecofriendly poly(butylene succinate) extended with 1,6-diisocynatohexane composted with L-histidine (PBSLH) polymer composite was synthesized by condensation polymerization. The polymer composite was characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM-EDX). The inhibition action of the polymer composite was investigated by conventional weight loss, potentiodynamic polarization, variable amplitude micro (VASP), and electrochemical impedance spectroscopy (EIS). The maximum corrosion inhibition efficiency of 78 % was obtained at concentration level of 600 ppm. The results revealed PBSLH as a mixed type corrosion inhibitor. The thermodynamic and kinetic parameters also revealed adsorption of PBSLH on to mild surface as exothermic and the adsorption was conformed to Langmuir model. The morphology of mild steel coupons was investigated by SEM and atomic force microscope (AFM) and the results showed PBSLH to have inhibited corrosion on mild steel in 1 M HCL.

/pdf/corrosion-inhibition-of-mild-steel-by-poly-butylene-5a0jgs7cq6.pdf

Corrosion Inhibition of Mild Steel by Poly(butylene succinate)-L-histidine Extended with 1,6-diisocynatohexane Polymer Composite in 1 M HCl

This article describes the thermal and thermomechanical properties of poly(butylene succinate) (PBS) and its nanocomposites. PBS nanocomposites with three different weight ratios of organically modified synthetic fluorine mica (OMSFM) have been prepared by melt-mixing in a batch mixer at 140 degrees C. The structure and morphology of the nanocomposites were characterized by X-ray diffraction (XRD) analyses and transmission electron microscopy (TEM) observations that reveal the homogeneous dispersion of the intercalated silicate layers into the PBS matrix. The thermal properties of pure PBS and the nanocomposite samples were studied by both conventional and temperature modulated differential scanning calorimetry (DSC) analyses, which show multiple melting behavior of the PBS matrix. The investigation of the thermomechanical properties was performed by dynamic mechanical analysis. Results reveal significant improvement in the storage modulus of neat PBS upon addition of OMSFM. The tensile modulus of neat PBS is also increased substantially with the addition of OMSFM, however, the strength at yield and elongation at break of neat PBS systematically decreases with the loading of OMSFM. The thermal stability of the nanocomposites compared to that of the pure polymer sample was examined under both pyrolytic and thermo-oxidative environments. It is shown that the thermal stability of PBS is increased moderately in the presence of 3 wt% of OMSFM, but there is no significant effect on further silicate loading in the oxidative environment. In the nitrogen environment, however, the thermal stability systematically decreases with increasing clay loading.

Mamookho Elizabeth Makhatha

Papers

Toxic Metal Implications on Agricultural Soils, Plants, Animals, Aquatic life and Human Health

Effects of rapid solidification on the microstructure and surface analyses of laser-deposited Al-Sn coatings on AISI 1015 steel

Thermal properties of poly(ethylene succinate) nanocomposite

Corrosion Inhibition of Mild Steel by Poly(butylene succinate)-L-histidine Extended with 1,6-diisocynatohexane Polymer Composite in 1 M HCl

Thermal and thermomechanical properties of poly(butylene succinate) nanocomposites.