Sergejs Gaidukovs

Thermo-mechanical properties of polyurethane modified with graphite oxide and carbon nanotube particles

ABSTRACT The aim of the proposed paper is to synthesize graphite oxide (GO) and use it in combination with carbon nanotubes (CNT) for the preparation of polyurethane (PU) composites. We fabricated composites with CNT/GO content of 0.05, 0.1, 0.3 wt.% with the use of ultrasonic treatment and tested their thermo-mechanical properties. Thermo-mechanical analysis (TMA) and dynamic mechanical analysis (DMA) measurements for CNT/GO composites were compared with the unfilled PU. Thermo-mechanical characteristics of storage moduli and loss moduli for CNT/GO nanocomposite were improved in comparison to the unfilled PU. The introduction of CNT/GO to the PU matrix creates strong bonding with the matrix and leads to the decrease of the glass transition temperature, new solid-solid phase transitions of polymer in the glass state. Dilatometric curves testified the remarkable changes in the glass transition of the polymer after the introduction of CNT/GO hybrid filler. Thermal expansion coefficient was calculated from the curve slopes and expressed continuously increasing expansion rate for CNT/GO composite. The measured characteristics were directly dependent from the filler content in the composite and the operated temperature.

Application of amber filler for production of novel polyamide composite fiber

The present investigation is connected to the field of medical textiles, which includes the development and application of composite fibers. The aim of the paper is the processing and investigation of polyamide 6 (PA6)–amber composite fibers. The use of amber filler for the preparation of a new type of polymer composite fiber is described in detail for the first time. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and granulometry testing were used to test the structure and the size of the prepared amber particles. The obtained amber particles were characterized by an average size of up to 3 µm and a regular shape. Fourier transform infrared (FTIR) spectroscopy investigations showed that amber in the dispersed state does not change its chemical structure and contains one of the active compounds—succinic acid. The effect of the amber filler inclusion on the melt-spinning routes of fully drawn yarns (FDY) and pre-oriented yarns (POY) was determined. Amber composite fibers general use is medical fabric (compression socks and tights); it is biocompatible with skin cells.

Microwave Synthesis Of Polyols For Urethane Materials

The preparation of polyurethane (PU) polyols processed with the use of microwave (MW) irradiation heating polyols is reported. The PU polyols were consisted from bio-based rapeseed oil (RO) and recycled polyethylene terephthalate (PET) components are reported. Obtained MW polyols were compared to the conventional PU polyols synthesized by traditional heating in oil bath. The polyols have the similar properties. The obtained MW assisted polyols were characterized by Fourier transform infrared spectroscopy (FT-IR) measurements. Acid number, hydroxyl value, moisture content and viscosity of the MW synthesized polyols were measured. The obtained polyols consisted from about 34% RO and 23% PET components. The advantages of the very fast reaction rate for preparation of PU polyols, by using MW instead of the conventional heating process, are shown.

Enhanced mechanical, conductivity, and dielectric characteristics of ethylene vinyl acetate copolymer composite filled with carbon nanotubes:

We report high mechanical, dielectric, and thermal performance of carbon nanotubes (CNT) reinforced ethylene vinyl acetate (EVA) composites, fabricated using conventional melt extrusion processing. CNT have extremely high stiffness, electrical conductivity, and surface area, ensuring strong interactions with the polymer and effective reinforcement. The addition of CNT to EVA leads to an extremely high yield strength and Young’s modulus of the composites. The EVA composite produced, containing 5 wt% CNT, exhibited an almost 3-fold increase in Young’s modulus and a 2.2-fold improvement of yield strength compared to neat EVA. However, the composite maintained high deformation properties—a ductility of 1300%. Scanning electron microscopy analysis evidences the agglomeration of the CNT in the EVA/CNT composites. The EVA/CNT composites gained excellent electrostatic discharge properties—a surface resistivity in the range of 108 Ω/square. The observed thermal conductivity of the composites was increased by about 30% without losing the electrically insulating performance.

Manufacturing of Amber Particles Suitable for Composite Fibre Melt Spinning

Abstract Polyamide fibre containing amber particles was fabricated. The amber particles were obtained by grinding technology using planetary ball-mills. Scanning electron microscopy and granulometry testing were used to characterise the structure and the size of prepared amber particles. Fourier transform infrared spectroscopy was used to analyse the chemical structure of the amber particles. The amber particles were characterised with average size up to 3 μm. The chemical composition of amber before and after the grinding remained unchanged. The amber particles were melt-extruded using polyamide 6 as the matrix. Melt spinning processing was used to fabricate polyamide-amber filaments. Pre-oriented yarns and fully drawn yarns were obtained after hotdrawing experiments. Reported experimental findings of amber composite fibre could be important for textile applications.

Effect of Low-Content of Graphene and Carbon Nanotubes on Dielectric Properties of Polyethylene Oxide Solid Composite Electrolyte

Preparation of polymeric nano-composites with finely controlled structure, especially, at nano-scale, is still one of the most perspective modification ways of the properties of polymeric composites. Paper actuality is based on growing need for non-combustible and safe battery electrolytes, which operate portable electronic devices. Polyethylene oxide solid composite electrolytes containing lithium triflate, multiwall carbon nanotubes and graphene by solution casting and hot-pressing method were prepared. Dielectric spectroscopy, surface resistivity measurements were performed to evaluate nanoparticles influence on the dielectric characteristics of the electrolyte material. Observed enhancement of dielectric conductivity is connected to the addition of the Li+ ions and incorporation of the electrically conductive nanoparticles to the polymer electrolyte