Introduction Of Microspheres Research Articles

Research on the early age mechanical properties of concrete based on hydration kinetics

Abstract. In the era of advanced construction techniques, the enhancement and regulation of the functionality of concrete, a widely utilized construction material, has gained significant prominence. The study delves into the exploration of the properties and heat reaction behavior during hydration of various composite cementitious materials with the incorporation of three distinct mineral additives: microspheres, cellulose, and early strength shrinkage reducing agent for early strength enhancement. Analyzing the impact of cement hydration reactions on the early-age performance of concrete, the Krstulovic-Dabic hydration kinetics model was utilized to simulate and study the hydration process of the composite cementitious system in concrete. The findings reveal that the introduction of microspheres and cellulose hinders the advancement of early-age strength in concrete, whereas the utilization of an early strength shrinkage reducing agent proves to be beneficial in enhancing early-age strength. Enhancing the hydration reaction rate is observed with the addition of early strength shrinkage reducing agent, whereas the presence of microspheres and cellulose slows down this process. The rate of hydration reaction accelerates, resulting in a greater early-age strength of the concrete.

The Study of Composite Materials Properties Based on Polymers and Nano-Additives from Industrial Wastes from Kazakhstan.

This research is aimed at studying the properties of polymer anticorrosion coatings based on ED-20 resin widely used in practice and industrial wastes. In this work, three basic types of nanoscale nanofillers were chosen: dispersed particles-microsilica, microspheres obtained at Kazakh enterprises, and carbon nanotubes. Physicochemical research methods were used in the research: a laser analyzer for studying the dispersibility of industrial waste and spectrometric research methods. The properties of materials were investigated by standardized methods. The obtained results show that the introduction of microsilica and microspheres obtained at Kazakhstani enterprises, used as additives, improves both the physical and mechanical properties of epoxy composites compared to the standard (control) material. The results of experiments have shown that the optimal content of additives of microsilica and microspheres provides an improvement in the physical and mechanical properties of epoxy composites in comparison with the standard (control) material. Studies have shown that the introduction of microspheres into ED-20 polymer increases impact toughness. The introduction of microsilica into the matrix contributes to the increase of elastic modulus. Experimental studies of optical properties of samples of carbon composite polymer films based on polystyrene (PS) with additives of carbon nanotubes C60 and C70 and multilayer carbon nanotubes were also carried out. The experimental results obtained for the optical properties of polymer composites based on basic polymers from solid waste and carbon nanotubes showed that the optical properties of polymer composites undergo noticeable changes.

Investigation of the influence of hollow aluminosilicate microspheres on properties of elastomer fire-thermal protective coatings

The paper considers the influence of the introduction of aluminosilicate microspheres on value of the Payne effect, rheometric, physico-mechanical thermophysical and fire-heat-shielding properties of the elastomer compositions used in the thermal protective coatings based on ethylene-propylene rubber. It was found that partial sorption of vulcanization accelerators and sulfur can occur on the surface of microspheres, followed by their desorption at the vulcanization temperature. This is confirmed by the appearance of a second peak on the vulcanization rate curve. The use of hollow aluminosilicate microspheres in the composition of elastomeric fire-heat-shielding coatings makes it possible to increase the efficiency of these compositions by reducing the thermal conductivity and density of the article while saving the optimum level of physico-mechanical properties. In accordance with the proposed mechanism for the interaction of the polymer matrix and microspheres, additional crosslinked structures are formed within the rubber matrix. An increase in the content of microspheres leads to an increase in the filler-filler interaction, which leads to a relative increase in thermal conductivity. However, the thermal conductivity of compositions containing relatively large amounts of the microspheres is still lower than that of the control. The introduction of microspheres slows down the heating of the sample during high-temperature tests, while reducing the loss of mass and the rate of linear combustion.

Prospects for reducing the density of polysulfide sealants

The possibility of reducing the density of polysulfide sealants by the introduction of microspheres is considered. The results of a study of the developed low-density polysulfide VGM-8 grade sealant are presented.

DYNAMIC MECHANICAL STUDIES OF POLYURETHANE COMPOSITES FILLED WITH GLASS MICROFILLERS

Ceramic microspheres with unique composition and diameter, modified by different surface treatments, were blended with polyurethane (PU) in various proportions to improve the visco-elastic and mechanical properties of PU composites. Results of dynamic mechanical spectra indicate that the introduction of micro-beads H50, D32 and K37 into the PU network leads to the shift of glass transition temperature. Besides, the intensity of loss tanδ of PU composites decreased as a function of the filler's concentration, due to reduced concentration of polymer backbones. Both the shift of Tg as well as the changes of loss tanδ show that the introduction of microspheres not only creates physical bonding with PU but also causes steric effects due to the adsorption of N−H and C=O functional groups of PU on the filler surface. However, the introduction of various microfillers shows the composites to have different Young's modulus. This evidence shows that the rigidity and elasticity of polymer composite can be finely tuned by the introduction of various surface-treated microfillers as well as the amount of filler added.