Effects of Temperature and Duration of Anorthite Synthesis from Mixtures of Kaolin and Calcite

In this research, the effects of temperature and duration of anorthite synthesis were examined by DTA, TGA, XRD, SEM and EDS analysis. Anorthite was synthesized with mixtures of kaolin and calcite powders with a weight ratio of 7 to 3, at three different temperatures of 1000, 1200 and 1400 °C, and three different synthesis times of 30, 180 and 300 min. Different phases in the raw materials mixture were formed during synthesis. These phases were investigated thoroughly to determine the role of time and temperature in their formation. Results proved that synthesis at 3 h and 1200 °C was suitable for the reactions of anorthite formation

Surface Modification of Polyurethane Nano Coatings: Effect of Different Morphology of Mg(OH)2 Nanoparticles on Hydrophobicity

Researchers have always been interested in magnesium hydroxide along with its potential to be synthesized in a variety of morphologies and distinctive fire-retardant features. The hydrothermal method is one of the most effective techniques to synthesize nanoparticles with controlled size and shape, as well as high purity. In this study, the hydrothermal method was used to synthesize four distinct morphologies of MH, such as plate, flake, spherical, and disk, functionalized with APTES from magnesium chloride and sodium hydroxide raw materials. The influence of each morphology on surface roughness and hydrophobicity of Polyurethanes nanocomposite was then investigated using different analyses such as XRD, SEM, AFM, and contact angle. The observations demonstrated that the presence of nanoparticles with different morphologies would lead to different surface topography. Thanks to the surface roughness, extremely high water contact angles were obtained showing the super hydrophobic behavior of the developed nanocoatings

Novel Synthesis of Nano Mg(OH)₂ by Means of Hydrothermal Method with Different Surfactants

Magnesium hydroxide (MOH) is a widely used inorganic chemical owing to its various properties. Hence, researchers have long studied its synthesis and its unique features. However, the morphological consequences have rarely been studied. Despite having several benefits for synthesizing nanoparticles, the hydrothermal method’s main drawbacks are its lengthy processing time and the high cost of raw materials. This research aimed to use more easily obtainable raw materials in a reasonably short time to synthesize MOH in various morphologies. For this purpose, we prepared different samples using the same hydrothermal method to investigate the effects of the precursor and surfactant on the structure, morphology, and size of MOH particles. The results of XRD and FTIR analysis demonstrated that a temperature of 180 °C and a duration of 18 h is not sufficient for MgO as a precursor to obtaining MOH in the hydrothermal method. However, in the presence of different surfactants, MgCl2 resulted in nanoparticles with hexagonal structure and plate, flake, spherical, and disc morphologies

Pozzolanic activity of mechanochemically and thermally activated kaolins in cement

This paper reports on the mechanochemical activation by intensive grinding as an alternative way to produce pozzolanically reactive metakaolin. The physicochemical properties, pozzolanic reactivity and impact on cement hydration of mechanochemically and thermally activated kaolinitic clays were compared. Mechanochemical activation of kaolin led to an amorphous hydrous material with increased specific surface area and high water content. Unlike in thermally activated kaolins, the Al coordination environment was partially retained during mechanochemical treatment. At low clinker replacement levels of 10%, the use of mechanochemically activated kaolins accelerated the hydration of the blended cement. The pozzolanic reaction reduced portlandite contents strongly and from early on. The combined effect of enhanced cement hydration and pozzolanic reaction at early ages was reflected in a higher early age strength development (up to 7 days). The differences between mechanochemically and thermally activated kaolins largely disappeared at later ages. (C) 2015 Elsevier Ltd. All rights reserved