Applied Mechanics and Materials Vols. 752-753

Abstract: This article focuses on the evaluation of tests with a small repeatability which are characterized by their financial or time demands. The beginning of the article assess the current state of the problem and different approaches to it, focusing on the evaluation of creep tests characterized especially by their very typical little repeatability. Then the article describes the method for testing the creep properties of the irradiated material at raised temperatures. Next, the results are graphically confronted with the subjective evaluation of the observer and using the Mann-Whitney test. This test is used to determine whether the measured data comes from the same basic set or originate with the chosen confidence level. The results show the significance of the use of this test which is calculated with a certain probability.

Abstract: The paper presents an experimental study of the effect of beta radiation on nanomechanical properties of surface layer of PBT. Irradiation of polymers initiates cross-linking process in the structure especially in nanolayers. Applied radiation doses (66, 132 and 198 kGy) caused different nanomechanical changes which have a significant effect on the final properties of the tested PBT. Beta irradiation of the examined thermoplastic caused the growth of values of material parameters as nanoindentation hardness, nanoindentation modulus or deformation work. The improvement of nanomechanical properties was measured by the nanoindentation test.

Abstract: In this paper, the effect of the electron beam irradiation on the indentation hardness, indentation modulus and indentation creep have been studied by means of the Depth sensing indentation (DSI). Cross-linking is a process in which polymer chains are associated through chemical bonds. Radiation doses of 33, 66 and 99 kGy were used for unfilled polyamide 6 with the 7% crosslinking agent (triallyl isocyanurate). Beta irradiation of the examined thermoplastic caused the growth of values of material parameters as micro-hardness, indentation modulus or indentation creep etc. From this point of view, there may be new application in areas with mechanical properties higher than their original properties. This study compared the mechanical properties of irradiated and non-irradiated PA6.

Abstract: This research paper suggests a possible solution for a growing problem of irradiated materials ́ waste processing. Recycled radiation crosslinked polyamide 6 (rPA6_x) was used as a filler into non-modified polyamide 6 (PA6) in several concentrations. Influence of the amount of the filler on mechanical properties of resulting blends was investigated. Tensile test was carried out at two temperatures to determine mechanical behavior. Results show that there is a little difference at all observed material characteristics in comparison with non-modified PA6. According to the results it was proven that there is a possible utilization of such modified materials after the end of their service life but some other properties have to be examined.

Abstract: Growing usage of radiation crosslinked plastic materials and utilization of their advantageous properties might raise a question of their future recycling. This paper deals with utilization of recycled irradiated polyamide 6 (rPA6_x) which is used as a filler into low and high-density polyethylene (LDPE/HDPE) in concentrations 10 and 30 %. Mechanical properties of such blends were investigated and compared. Both blends show similar trend at all observed material characteristics. Elastic modulus representing material stiffness grown with increasing amount of the filler. Ultimate tensile strength and impact toughness decreased and hardness slightly increased. All the obtained results show that it is possible to use recycled radiation crosslinked PA6 as a filler but it is necessary to count with properties change.

Abstract: Radiation processing of polymers is a well-established and economical commercial method of precisely modifying the properties of polymers, especially temperature stability. The tensile behaviour of modified HDPE samples by radiation cross-linking were measured at the ambient and after temperature load. Sample 3D scans were made and investigated before and after temperature load. The tested samples showed significant changes of temperature stability. From this point of view, new applications could also be seen in areas with service temperatures higher than their former melting point.

Abstract: In this study there was found that radiation cross-linking increased the surface energy of high-density polyethylene (HDPE), and low-density polyethylene (LDPE). Surface energy affects the wettability of the surface and is very important for creating of high-quality bonded joints. The measurement results indicated that radiation cross-linking was a very effective tool for the improvement of adhesive properties and increased the surface energy of selected polyolefins. Surfaces of selected materials with ionizing beta radiation with doses of 0, 33, 66, 99, 132, 165, and 198 kGy were irradiated. The best results were achieved by irradiation at dose of 165 kGy. The surface energy after irradiation was increased up to 100 % compared to untreated material.

Abstract: Experimental technique of turbine blades dry-friction dampers efficiency estimation is presented. Dummy turbine blades with underplattform friction dampers were used as a investigation objects. Experimental and numerical results of system modal characteristics changes and friction dampers parameters have been obtained for the range of centrifugal forces 0...149 N acting on the damper.

Abstract: Right used computational analyses are commonly good tool for technical industry to improve process. This paper shows using computational analysis during injection molding process and shows using computational analysis to improve the injection molding process. The main aim of the paper is presenting differences between effects on non-Newtonian behavior on cure rate in final product in rubber process. It was found that for specific geometry and processing conditions, increase in the index of non-Newtonian behaviour increases the curing rate due to viscous dissipation taking place at the flow domain walls. It was shown for variable flow rate.

Abstract: The process of radiation crosslinking helps to improve some mechanical properties of polymer materials. Some types of polymers do not cross-link during radiation crosslinking but degrade. In order to create 3D net in the polymer structure it is necessary to add a crosslinking agent. The specimens were prepared by injection technology with the TAIC crosslinking agent at 0, 1, 2 and 3 %. The changes of micromechanical properties of the surface layer were measured by instrumented microhardness test. It was found that micromechanical properties of the surface layer of the tested polyamide changed.