Nano-Modified Meta-Aramid Insulation Paper with Advanced Thermal, Mechanical, and Electrical Properties

Molecular dynamics simulations were used to analyze the internal mechanism for the observed improvement in performance of nano-modified meta-aramid insulation paper from a microscopic point of view. The results showed that the k-polyphenylsilsesquioxane(PPSQ) modified meta-aramid insulation paper was superior to b-PPSQ modified meta-aramid insulation paper in terms of its thermal stability and mechanical and electrical properties. The analysis of microscopic parameters showed that the stiffness of k-PPSQ was less than that of b-PPSQ, and the hydroxyl groups on the open-loop system were more likely to enter the dispersed system, resulting in higher bonding strength, meta-aramid fiber chains between k-PPSQ molecules, and the formation of hydrogen bonds. Additionally, the nano-enhancement effects of k-PPSQ and b-PPSQ resulted in various improvements, including a reduction in pores between molecules in the blend model, an increase in the contact area, the formation of interfacial polarization, and a reduction in defects at the interface.

Composites Composed of Hydrophilic and Hydrophobic Polymers, and Hydroxyapatite Nanoparticles: Synthesis, Characterization, and Study of Their Biocompatible Properties

The creation of artificial biocomposites consisting of biocompatible materials in combination with bioactive molecules is one of the main tasks of tissue engineering. The development of new materials, which are biocompatible, functional, and also biodegradable in vivo, is a specific problem. Two types of products can be formed from these materials in the processes of biodegradation. The first types of substances are natural for a living organism and are included in the metabolism of cells, for example, sugars, lactic, glycolic, and β-hydroxybutyric acids. Substances that are not metabolized by cells represent the other type. In the latter case, such products should not be toxic, and their concentration when entering the bloodstream should not exceed the established maximum permissible level. The composite materials based on a mixture of biodegradable synthetic and natural polymers with the addition of hydroxyapatite nanoparticles, which acts as a stabilizer of the dispersed system during production of the composite, and which is a biologically active component of the resulting matrix, were obtained and studied. The indirect effect of the shape, size, and surface charge of hydroxyapatite nanoparticles on the structure and porosity of the formed matrix was shown. An in vivo study showed the absence of acute toxicity of the developed composites.

Polishing of precision parts of optical-electronic and laser equipment

The mechanism of interaction of the optical surface with the polishing dispersed system during polishing is investigated. It is established that the energy transfer between them is a consequence of the dipole-dipole interaction in the donor-acceptor system and occurs by the Ferster mechanism. It was found that the decrease in the spectral separation between the treated material and the particles of polishing powder causes an increase in the size of sludge particles and wear particles, which leads to an increase in the roughness parameters Ra, Rq, Rmax of optical surfaces during polishing by polishing dispersed sys-tems. It is shown that the polishing productivity of optical surfaces and the wear intensity of polishing powder particles decrease with increasing corresponding transfer energies, which confirms the main pro-visions of the cluster theory of polishing of nonmetallic materials and the validity of quantum mechanical description of resonant energy transfer mechanism between dispersed material and dispersed system.

Research on a Fractal Dimension Calculation Method for a Nano-Polymer Microspheres Dispersed System

Polymer microspheres (PMs) are a kind of self-similar volume expansion particle, and their fractal dimension varies with hydration swelling. However, there is no unique fractal dimension calculation method for their characteristics. A new model is established in this paper, which is particular to calculate the fractal dimension of PMs. We carried out swelling hydration experiments and scanning electron microscope (SEM) experiments to verify the new model. The new model and the box-counting model were used to calculate the fractal dimensions of PMs based on the hydration experiment results. Then, a comparison of the calculation results of the two methods was used to verify the validity of the model. Finally, according to the new model calculation results, the fractal dimension characteristics of PMs were analyzed. The research results indicate that the new model successfully correlates the cumulative probability of the PMs dispersed system with the fractal dimension and makes fractal dimension calculation of PMs more accurate and convenient. Based on the experiment results, the new model was used to calculate the fractal dimension of PMs and the box-counting model, and its findings were all 2.638 at initial state hydration and 2.739 and 2.741 at hydration time as of day 1. This result verifies the correctness of the new model. According to the hydration swelling experiments and the new model calculation results, the fractal dimension is linear correlated to the average particle size of PMs and the standard deviation average particle size. This means the fractal dimension of PMs represents the space occupancy ability and space occupancy effectiveness.

Application of Fuel Ash as a Microfiller in Cement Dispersion Systems

The paper shows studies of modified cement compositions with micro-filler. As such a micro-filler, an ash product is used - an activated waste of an ash-and-slag mixture. The enriched aluminosilicate waste is characterized by a fairly stable chemical and particle size distribution. The used activation of the ash product allows for a more dense packing of particles in the composition of the binder dispersed system. The high dispersion of the ash component requires additional plasticization of the dispersed system. Despite the fact that during the activation process the destruction of large-pore particles remaining after flotation occurs, the introduction of a plasticizer also improves the rheological characteristics of the compositions, and, consequently, increases the strength and density of the modified cement stone with the addition of a microfiller.

Modelling and experimental investigation of ARGET/AGET atom transfer radical polymerization systems

Activators Generated by Electron Transfer (AGET) and Activators Regenerated by Electron Transfer (ARGET) Atom Transfer Radical Polymerization (ATRP) are emerging topics within the polymerization field. These techniques allow for better control over polymer structure and polymer size distributions than conventional polymerizations. However, investigations into these processes are lacking, especially from a modelling point of view. Therefore, a kinetic model of the ARGET ATRP of butyl methacrylate (BMA) in a solution medium and Hybrid Monte Carlo model of the AGET ATRP of butyl acrylate (BA) in a dispersed system were developed and compared with data. In addition, an experimental investigation of the AGET ATRP of BA was carried out to study the kinetic aspects of this polymerization. The results of these studies demonstrate that both models have relatively strong predictive powers, and that different kinetic regimes appear to be available within the dispersed system studied experientially.

Modelling and experimental investigation of ARGET/AGET atom transfer radical polymerization systems

Activators Generated by Electron Transfer (AGET) and Activators Regenerated by Electron Transfer (ARGET) Atom Transfer Radical Polymerization (ATRP) are emerging topics within the polymerization field. These techniques allow for better control over polymer structure and polymer size distributions than conventional polymerizations. However, investigations into these processes are lacking, especially from a modelling point of view. Therefore, a kinetic model of the ARGET ATRP of butyl methacrylate (BMA) in a solution medium and Hybrid Monte Carlo model of the AGET ATRP of butyl acrylate (BA) in a dispersed system were developed and compared with data. In addition, an experimental investigation of the AGET ATRP of BA was carried out to study the kinetic aspects of this polymerization. The results of these studies demonstrate that both models have relatively strong predictive powers, and that different kinetic regimes appear to be available within the dispersed system studied experientially.