Petr Kratky

Micro-Hardness and Morphology of LDPE Influenced by Beta Radiation

This article deals with the influence of different doses of Beta radiation to the structure and mico-mechanical properties of Low-density polyethylene (LDPE). Hard surface layers of polymer materials, especially LDPE, can be formed by radiation cross-linking by β radiation with doses of 33, 66 and 99 kGy. Material properties created by β radiation are measured by micro-hardness test using the DSI method (Depth Sensing Indentation). Individual radiation doses caused structural and micro-mechanical changes which have a significant effect on the final properties of the LDPE tested. The highest values of micro-mechanical properties were reached at radiation dose of 66 and 99 kGy, when the micro-hardness values increased by about 21%. The changes were examined and confirmed by X-ray diffraction.

Comparison of the Results of Creep and Micro-Indentation Creep to Irradiated HDPE

The main goal of this paper is to compare measurements of creep behavior of Crosslinking polymer materials. Creep properties have been measured by two methods, first is micro-indentation with Depth Sensing Indention (DSI) and the second method is long-term creep test in room temperature. By using of these principally different methods can be better analyzed the influence of radiation netting, and therefore better suggest an appropriate dose of radiation with respect to use of polymer material in practice. The evaluation criteria for DSI test is index CIT [%]. The evaluation criteria for the standard creep test is value of average elongation at the end of the test. Comparison of these two values shows slight influence of radiation dose with using the standard creep test instead of using micro-indentation creep test, which shows very slight influence of radiation dose on material.

Effect of Beta Irradiation on Microhardness of Polyamide 6

The polymer additional cross-linking influences the surface nano and micro layers in the way comparable to metals during the thermal and chemical-thermal treatments (e.g. surface hardening, cementation). Our research confirms the comparable properties of surface irradiated polyamide 6 (PA6) with high performance polymers. The surface layer of polymer material such as polyamide 6 is modified by β – radiation. Material properties of the surface layer created are measured by microhardness test using the DSI method (Depth Sensing Indentation). The influence of irradiation dose on mechanical properties (materials parameter) of PA6 is a subject of this research.

Influence of Irradiation Doses on Mechanical Properties of Glass Fiber Filled PBT

The submitted paper compares mechanical properties of the hard surface layer of modified PBT filled by 35% of glass fibers. Hard surface layer was made by radiation cross-linking technology which allows polymer materials modification followed by the change of their end-use properties. The surface layer of polymer material is modified by β – radiation. When the polymer material is exposed to the β – radiation, it is possible to observe changes of the surface layer at applied load. The mechanical properties were measured by nanohardness test with using the DSI method (Depth Sensing Indentation).

Influence of Irradiation Doses on Mechanical Properties of PA6

The presented article deals with influence of mechanical properties of the hard surface layer of modified polyamide 6. The mechanical properties were acquired by nanohardness test with using the DSI method (Depth Sensing Indentation). Hard surface layer was created by radiation cross-linking technology. This technology allows polymer materials modification followed by the change of their end-use properties. The surface layer of polymer material is modified by β - radiation. When the polymer material is exposed to the β radiation, it is possible to observe changes of the surface layer at applied load.

Ionizing Radiation Effect of PBT Measured by Nano-Indentation Test

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.

Micro-Hardness of PA6 Influenced by Beta Irradiation

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.

Nanohardness of Electron Beam Irradiated Polyamide 6.6

Nanomechanical changes in the surface layer of polyamide 6.6 modified by beta radiation were measured by instrumented test of nanohardness. The specimens were prepared by injection technology and subjected to radiation doses of 0, 33, 66, 99, 132, 165, 198kGy. Measurements of nanohardness showed considerable changes of behavior of surface layer in middle as well as high radiation doses with higher values of indentation hardness and stiffness.

Ionizing Radiation Effect on PMMA Measured by Microhardness

The experimental study deals with the effect of modification of the surface layer by irradiation cross-linking on the mechanical properties of the Poly (methyl methacrylate) - PMMA tested using the instrumented microhardness test. The surface layer of PMMA specimen made by injection technology was modified by irradiation cross-linking using beta irradiation, which significantly influences mechanical properties of the surface layer. Compared to the heat and chemical-heat treatment of metal materials (e.g. hardening, nitridation, case hardening), cross-linking in polymers affects the surfaces in micro layers. These mechanical changes of the surface layer are observed in the instrumented microhardness test. Our research confirms the comparable properties of surface layer of irradiated PMMA with highly efficient polymers. The subject of this research is the influence of irradiation dosage on the changes of mechanical properties of PMMA.

Effect of Beta Irradiation on the Strength of Bonded Joints of HDPE

At the present time bonding has spread into almost all sectors of practice and it would be very difficult to find an industry in which there is no need to use this technology of joining a wide range of materials. In comparison with conventional joining methods (riveting, welding and screwing) provides bonding new combination of options and allows obtaining special shapes and properties which cannot be created by conventional methods of coupling. For the formation of quality bonded joint it is important that the adhesive bonding surface is well wetting. Wettability is characterized by the contact angle of wetting. The liquid must have a lower surface tension than the solid in order to be able to wetting the solid substance. This article describes the effect of beta irradiation on the contact angle of wetting, on the surface energy and on the final strength of bonded joints of HDPE.