Gerda Gaidukova

Characterization of Strong and Crystalline Polyvinyl Alcohol/Montmorillonite Films Prepared by Layer-by-Layer Deposition Method

The preparation of a high-strength and highly crystalline nanocomposite with a layered structure by the use of layer-by-layer deposition (LbL) method from polyvinyl alcohol (PVOH) and montmorillonite (MMT) platelets is reported. The crystallinity and interactions between the components were studied by the use of Fourier transform infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The nanocomposite film structure was investigated by the use of scanning electron microscope (SEM) and atomic force microscopy (AFM). The stiffness of the LbL PVOH/MMT film was significantly higher compared to pure PVOH and conventional PVOH/MMT nanocomposite. The structural and thermal studies on thin PVOH/MMT films indicated the enhanced crystallinity of the polymer.

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.

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.