Ľudmila Dulebová

Evaluation of Process Wear of Selected Tool Steels for Injection Molds

The aim of this contribution is to test the suitability of selected types of tool steels used for manufacturing of injection molds. Experiments were realized by the simulation of adhesive wear using laboratory equipment Amsler, which allows the testing of grinding pairs. Evaluated grinding pairs consisted of tool steel and two types of roundels. Tested polymeric materials were based on pure PA6 and PBT filled with short glass fibers, prepared by mixing process in twin screw extruder. The wear of five types of tool steels were evaluated by weight decrease before and after the experiment, while changing the friction coefficient of grinding pairs, material of grinding pairs and sensing the roughness of steel before and after wear.

Preparation and Characterization of Polypropylene/MMT Nanocomposites

In this paper, study of preparation and testing of polymer nanocomposites (PNC) based on polypropylene matrix and montmorillonite nanofillers is described. Samples were prepared by twin-screw extrusion and injection molding to final shape. Changes of basic properties of these PNC ́s were tested and described in main part of this article.

Nanocomposites on the Basis of Thermoplastics and Montmorillonite Modified by Polyvinylpyrrolidone

A new method of layered silicate (montmorillonite) intercalation by polyvinylpyrrolidone in the solution under ultrasonic treatment is described in this work. The structure and thermophysical properties of the developed nanomodifier and the components rational ratio have been investigated. The effect of intercalated montmorillonite on physico-mechanical, thermophysical and insulating properties of polycaproamide PA-6 has been determined.

Sorption Capable Film Coatings with Variable Conductivity

The possibility of formation of coatings based on co-polymers 2-hydroxyethylmethacrylate with polyvinylpirrolidone on different nature surfaces is determined. It is investigated, that adsorption of liquid compositions components to surface-base affects the formation of coating from such compositions. The composite metal-filled coatings are obtained on the basis of synthesized polymers. Such coatings are characterized by variable conductivity dependently on moisture content, pH and low-molecular substances availability.

Possibility of Increasing the Mechanical Strength of Carbon/Epoxy Composites by Addition of Carbon Nanotubes

The development of nanoparticle reinforced polymer composites is presently seen as one of the most promising approaches in the field of future engineering applications. The unique properties of at least some of these nanoparticles (e.g., CNTs or carbon black) and the possibility of combining them with conventional reinforcements (e.g., carbon-, glass-or aramid-fibers) has led to an intense research in the field of nanocomposites. This study presents mechanical properties of two carbon composites made from bisphenol A epoxy resin (E) and 3 layers of 160 g/m2 carbon cloth with twill (TC) and plain (PC) weave as a reference and three-composite system that consists from carbon fiber reinforced epoxy matrix and 1% of multi-wall carbon nanotubes dispersed in epoxy resin. Used hardener H507 was based on cycloaliphatic polyamine with absence of nonylphenol. Samples were also tempered at 80 oC (for 12hours) for improvement of their thermal resistance.

The Influence of Modifying HDPE on Properties of the Surface

The aim of the paper was to discover the influence of modifying HDPE with selected agents that is a blowing agent, in the course of the extrusion process, inclusive of determination how the modification affects selected physical properties and properties of the surface of HDPE extrusion product. Endothermic chemical blowing agents in the amount of 0.6 % by mass were used in the research. The article presents selected results of examination of melt flow rate (MFR) and microscopic structure.

The Effect of Adding Halloysite Nanotubes as Filler on the Mechanical Properties of Low-Density Polyethylene

Reinforcing thermoplastic polymers with nanotubes or nanoplatelets to form nanocomposites is a way to increase the usage of polymeric materials in engineering applications by improving their mechanical properties. The contribution presents the results of research from basic processing and mechanical properties of nanocomposites. Low-Density Polyethylene (LDPE) was used as a matrix for experiments. The material LDPE was modified by Halloysite nanotubes (HNT) with a mass share of 2, 4, 6 wt% of the matrix. Nanocomposites were filled with 5 wt% Polyethylene grafted with maleic anhydride (PE-graft-MA) as a compatibilizer. The specimens were prepared by injection molding and their selected mechanical properties were tested by static tensile test, Charpy impact test and Shore hardness test.

Analysis of the Mechanical Properties Change of PA6/MMT Nanocomposite System after Ageing

The paper deals with the influence of environmental degradation on the change of the mechanical properties of polymer nanocomposites. The tested material was polyamide (PA) filled with nanoclay fillers Cloisite 30B, Cloisite 93A and Cloisite Na + in a volume of 2, 4 and 6 wt%. Test samples were produced by injection molding and were subjected to 540 hours and 1080 hours of UV radiation. The change of mechanical properties of PA6/MMT nanocomposite systems after the ageing in the UV chamber was studied by tensile test and Charpy impact resistance test. Article also compares structure of PA6/MMT nanocomposite.

Calibrator device for the extrusion of cable coatings

Abstract This paper presents selected results of theoretical and experimental research works on a new calibration device (calibrators) used to produce coatings of electric cables. The aim of this study is to present design solution calibration equipment and present a new calibration machine, which is an important element of the modernized technology extrusion lines for coating cables. As a result of the extrusion process of PVC modified with blowing agents, an extrudate in the form of an electrical cable was obtained. The conditions of the extrusion process were properly selected, which made it possible to obtain a product with solid external surface and cellular core.

Prediction and Verification of Compatibility of MMT Nanofiller in PA6 Matrix

This contribution deals about study of mechanical properties and compatibility between PA6 polymer as matrix and modified and unmodified montmorillonite clay nanofiller Cloisite. For this purposes in the first part of study the Hamaker constants, Adhesion work and B parameter for systems PA6/Cloisite 30B, PA6/Cloisite 93A and Pa6/Cloisite Na+ were calculated and compared. The second part of article consists of mechanical tests (tensile test, impact test) of moulded samples and Scanning Electron Microscope (SEM) study of these samples.