Search

Polyethylenes are the most widely used polymers and are gaining more and more interest due to their easy processability, relatively good mechanical properties and excellent chemical resistance. The disadvantage is their low temperature stability, which excludes particular high-density polyethylenes (HDPEs) for use in engineering applications where the temperature exceeds 100 degrees C for a long time. One of the possibilities of improving the temperature stability of HDPE is a modification by accelerated electrons when HDPE is cross-linked by this process and it is no longer possible to process it like a classic thermoplastic, e.g., by injection technology. The HDPE modified in this way was thermally stressed five times at temperatures of 110 and 160 degrees C, and then the dynamic tensile behavior was determined. The deformation and surface temperature of the specimens were recorded by a high-speed infrared camera. Furthermore, two thermal methods of specimen evaluation were used: differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The result of the measurement is that the modification of HDPE by accelerated electrons had a positive effect on the dynamic tensile behavior of these materials., IGA/FAI/2022/005; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: CZ.02.2.69/0.0/0.0/18_053/001787, European Structural and Investment Funds, Operational Programme Research, Development and Education under the project The Development of Capacity for Research and Development of TBU in Zlin [CZ.02.2.69/0.0/0.0/16_028/0006243]; Ministry of Education, Youth and Sports under the project International mobility of UTB researchers in Zlin II [CZ.02.2.69/0.0/0.0/18_053/001787]; Internal Grant Agency of Tomas Bata University [IGA/FAI/2022/005]

New technologies known as unconventional technologies make it possible to cut complex shapes at high speed and with relatively high precision. In many cases, especially in the case of thin sheet, created parts produced do not require any further treatment by post-machining. Knowledge of the accompanying phenomena, such as the heat-affected zone (HAZ) or the surface quality of the cutting edge, is necessary, for example, to assess further machining of material in these areas (e.g. drilling and reaming holes or finishing operations on the cutting edge). In this study, the thermal effect of four unconventional cutting technologies – laser, plasma, wire electrical discharge machining (wire EDM) and waterjet cutting on the cut surface of steel sheets is investigated. Steel 1.7102 (DIN 54SiCr6) was chosen for purpose of this study. The width of the HAZ and the nanohardness beneath the cut surface were analyzed.

Commodity polymers are a common part of everyday life. They consist mainly of polyolefins such as polyethylene, polypropylene. They are primarily used for ease of processing, cost and especially chemical resistance. The disadvantages of these polymers are low mechanical properties as well as temperature resistance. Any improvement in the mechanical properties can extend the application possibilities of the commodity polymers to the areas reserved for the construction polymers. This paper deals with changing two injection moulding process parameters - melt and mould temperature to high-density polyethylene (HDPE) surface hardness. HDPE hardness was measured using the method of Depth-Sensing Indentation (DSI) on three different instruments (ultranano-, nanoand micro-hardness tester). It has been found that as the melt and mould temperature increases, the hardness slightly increases.

The temperature ageing of high-density polyethylene (HDPE) modified by accelerated electrons was studied. Commodity plastic HDPE was used as a basic polymer material which was modified by radiation cross-linking. This polymer was used because of its excellent processability and chemical resistance. Plastic injection molding technology was used for the production of test specimens. These specimens were modified with the dose of radiation 33, 66, 99, 132, 165, and 198 kGy. The prepared specimens were tested to determine: gel content, degree of swelling, temperature stability, and changes in mechanical properties after temperature ageing. The results were determined by scanning electron microscopy (SEM) analysis on the fracture surfaces. The results of this study confirm that modification of HDPE by radiation cross-linking has a significant effect on increasing temperature stability. It has been shown that HDPE modified by radiation cross-linking can withstand temperatures exceeding the melting point of the original HDPE for a short-term. © 2022 by the authors. Licensee MDPI, Basel, Switzerland., LO1303, MSMT-7778/2014; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.0376

Irradiation of polymeric materials is a modern method of modifying their final properties (for example, improvements in mechanical, thermal and chemical properties). The main used types of radiation to modify polymers include ionic and ionizing radiation. Due to its properties, ionization beta (electron) radiation is the most widely used. The interaction of ionizing radiation with polymeric materials manifests as radiation cross-linking, which is a result of recombination of migrating polymer radicals into the amorphous region. In this type of radiation, electrons are generated under high vacuum using a hot cathode. Electrons emitted from the cathode are then accelerated in the electrostatic field that arises between the cathode and the anode. The depth of penetration into the material rises with increasing energy of electrons. This study examines the influence of ionizing beta radiation on the flammability index and ignition temperature of thermoplastic materials.

This study&rsquo, s goal was to describe the influence of a wide range of ionizing beta radiation upon the changes in surface layer mechanical properties and structural modifications of selected types of polymer. Radiation crosslinking is a process whereby the impingement of high-energy electrons adjusts test sample structures, thus enhancing the useful properties of the material, e.g., hardness, wear-resistance, and creep, in order that they may function properly during their technical use. The selected polymers tested were polyolefin polymers like polyethylene (Low-density polyethylene LDPE, High-density polyethylene HDPE). These samples underwent exposure to electron radiation of differing dosages (33, 66, 99, 132, 165, and 198 kGy). After the crosslinking process, the samples underwent testing of the nano-mechanical properties of their surface layers. This was done by means of a state-of-the-art indentation technique, i.e., depth-sensing indentation (DSI), which detects the immediate change in the indentation depth associated with the applied force. Indeed, the results indicated that the optimal radiation dosage increased the mechanical properties by up to 57%, however, the beneficial levels of radiation varied with each material. Furthermore, these modifications faced examination from the structural perspective. For this purpose, a gel test, Raman spectroscopy, and crystalline portion determination by X-ray all confirmed the assumed trends.

This study deals with high-density polyethylene (HDPE) which was put to the drop weight and tensile impact tests. HDPE is a semicrystalline thermoplastic polymer which is used in common applications such as packaging, consumer goods and car tanks. The injection moulded HDPE samples were subjected the drop weight impact test at different potential energies and the results were subsequently evaluated and discussed. The second test was performed on pendulum test machine where impact resistance in tensile was studied. It was found out that HDPE is a low-cost material with high-performance properties in the field of the impact resistance which was evaluated in penetration and tensile test where the plastic deformation creates.

Radiation processing of polymers is a well-established and economical commercial method of precisely modifying the properties of polymers, especially physical properties. The physical properties of modified polyamide 11 samples by beta rays were measured at the ambient and elevated temperature. The tested samples showed significant changes of physical properties between ambient (23°C) and elevated (80°C) temperature. From this point of view, new applications could also be seen in areas where more expensive materials are used, especially for application in automotive industry.

In this study there was compared the effect of different methods of modification (modification by plasma treatment and ionizing beta radiation) on the surface properties (contact angle of wetting and surface free energy) and on the final strength of bonded joints of selected types thermoplastics (low density polyethylene and polycarbonate). 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. Generally, for the formation of quality bonded joint it is important to wet the adhesive bonding surface well. Wettability is characterized by the contact angle of wetting. The liquid has to have a lower surface energy than the solid in order to be able to wet the solid substance.

This article deals with the measurement of the mechanical properties of a filled poly (butylene terephthalate) (PBT+35 % GF (glass fibres)) surface layer modified with beta radiation. Injection-moulded test bodies were subsequently irradiated with beta radiation using doses of (0, 33, 66 and 99) kGy. The measurement of the mechanical properties was realized with an ultra nano-hardness tester. The results of the measurements showed a considerable increase in the micromechanical properties (indentation hardness, indentation elastic modulus) when low doses of beta radiation were used. The aim of this paper is to study the effect of ionizing radiation at different doses on the ultra nano-hardness of the surface layer of poly (butylene terephthalate) (PBT) and compare these results with those for non-irradiated samples. The study was carried out due to the ever-growing use of this type of polymer, poly (butylene terephthalate) (PBT)., MEYS, Ministry of Education, Youth and Science; MSMT-7778/2014, National Landcare Programme; LO1303, National Landcare Programme; CEBIA-Tech, ERDF, European Regional Development Fund; CZ.1.05/2.1.00/03.0089, ERDF, European Regional Development Fund, TBU in Zlin [IGA/FT/2017/010]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [LO1303 (MSMT-7778/2014)]; European Regional Development Fund under project CEBIA-Tech [CZ.1.05/2.1.00/03.0089]

Using high doses of beta radiation for high-density polyethylene (HDPE) and its influence on the changes in the micromechanical properties of the surface layer has not been studied in detail so far. Specimens of HDPE were made with the injectionmoulding technology and irradiated with high doses of beta radiation (0, 132, 165 and 198) kGy. The changes in the micromechanical properties of the surface layer were evaluated using an ultra nano-hardness test. The results of the measurements showed a considerable increase in the micromechanical properties (indentation hardness, indentation elastic modulus) when high doses of beta radiation are used. The aim of this paper is to study the effect of ionizing radiation at different doses on the ultra nano-hardness of the surface layer of HDPE and compare these results with those for non-irradiated samples. The study was carried out due to the ever-growing use of this type of polymer HDPE., BGS, Biogeoscience Institute, University of Calgary; MEYS, Ministry of Education, Youth and Science; MSMT-7778/2014, National Landcare Programme; LO1303, National Landcare Programme; CEBIA-Tech, ERDF, European Regional Development Fund; CZ.1.05/2.1.00/03.0089, ERDF, European Regional Development Fund, TBU in Zlin [IGA/FT/2017/010]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [LO1303 (MSMT-7778/2014)]; European Regional Development Fund under project CEBIA-Tech [CZ.1.05/2.1.00/03.0089]

Using high doses of beta radiation for isotactic polypropylene (iPP) and its influence on the changes in the micromechanical properties of the surface layer has not been studied in detail so far. Specimens of isotactic polypropylene (iPP) were made with the injection-moulding technology and irradiated with high doses of beta radiation (0, 45, 66 and 99) kGy. The changes in the micromechanical properties of the surface layer were evaluated using an ultra nano-hardness test. The results of the measurements showed a considerable increase in the micromechanical properties (indentation hardness, indentation elastic modulus) when high doses of beta radiation are used. The aim of this paper is to study the effect of ionizing radiation with different doses on the ultra nanohardness of the surface layer of isotactic polypropylene (iPP) and compare these results with those of non-irradiated samples. The study was carried out due to the ever-growing use of this type of polymer, isotactic polypropylene (iPP)., BGS, Biogeoscience Institute, University of Calgary; MEYS, Ministry of Education, Youth and Science; MSMT-7778/2014, National Landcare Programme; LO1303, National Landcare Programme; CEBIA-Tech, ERDF, European Regional Development Fund; CZ.1.05/2.1.00/03.0089, ERDF, European Regional Development Fund, TBU in Zlin [IGA/FT/2017/010]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [LO1303 (MSMT-7778/2014)]; European Regional Development Fund under project CEBIA-Tech [CZ.1.05/2.1.00/03.0089]

Bonding is increasingly being used, and it is an ever-evolving method for creating unbreakable bonds. The strength of adhesive bonds determines, to a significant extent, the possible applications of this technology and is influenced by many factors. In addition to the type of adhesive used, the characteristics of the surface layers play a significant role, therefore, significant attention is paid to their adjustment and modification. Radiation crosslinking is one of the most important methods for modifying polymer properties. Currently, the most frequently used type of radiation for polymer crosslinking is beta minus (&beta, &minus, ) radiation, which affects not only mechanical but also surface properties, chemical and temperature resistance, and surface layer characteristics of polymers. This study investigated the effect of &beta, radiation on the surface layer properties of low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP) and the effects of surface-layer modification on the ultimate tensile strength of bonded joints. Based on the results, we concluded that &beta, radiation significantly changes the properties of the tested surface layers, increases the surface energy, and improves the adhesiveness of bonds. Consequently, the final strength of the LDPE, HDPE, and PP bonds increases significantly.

It was found in this study, that radiation crosslinking has a positive effect on the mechanical properties of selected type polyamide. In recent years, there have been increasing requirements for quality and cost effectiveness of manufactured products in all areas of industrial production. These requirements are best met with the polymeric materials, which have many advantages in comparison to traditional materials. The main advantages of polymer materials are especially in their ease of processability, availability, and price of the raw materials. Radiation crosslinking is one of the ways to give the conventional plastics mechanical, thermal, and chemical properties of expensive and highly resistant construction polymers. The main purpose of this paper has been to determine the effect of radiation crosslinking on the tensile strength and elongation of PA 66 (filled with 30 % glass fibers). These properties were examined in dependence on the dosage of the ionizing electron beam radiation (non-irradiated samples and those irradiated by dosage 66 and 132 kGy were compared) and on the test temperature (23, 50, 80, and 110 oC). Radiation cross-linking of PA 66 results in increased mechanical strength, and decreased of elongation. As an addition, the increased surface microhardness of polyamide was found.

The goal of this research was to examine the effect of two surface modification methods, i.e., radiation cross-linking and plasma treatment, on the adhesive properties and the final quality of adhesive bonds of polypropylene (PP), which was chosen as the representative of the polyolefin group. Polymer cross-linking was induced by beta (accelerated electrons&mdash, &beta, &minus, ) radiation in the following dosages: 33, 66, and 99 kGy. In order to determine the usability of &beta, radiation for these applications (improving the adhesive properties and adhesiveness of surface layers), the obtained results were compared with values measured on surfaces treated by cold atmospheric-pressure plasma with outputs 2.4, 4, and 8 W. The effects of both methods were compared by several parameters, namely wetting contact angles, free surface energy, and overall strength of adhesive bonds. Furthermore, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were conducted. According to our findings the following conclusion was reached, both tested surface modification methods significantly altered the properties of the specimen&rsquo, s surface layer, which led to improved wetting, free surface energy, and bond adhesion. Following the &beta, radiation, the free surface energy of PP rose by 80%, while the strength of the bond grew in some cases by 290% in comparison with the non-treated surface. These results show that when compared with cold plasma treatment the beta radiation appears to be an effective tool capable of improving the adhesive properties and adhesiveness of PP surface layers.

This study describes the effect of electron radiation on the nano-mechanical properties of surface layers of selected polyamide (PA) types. Electron radiation initiates the cross-linking of macromolecules in the polyamide structure, leading to the creation of a 3D network which fundamentally changes the properties of the tested polymers. Selected types of polyamide (PA 6, PA 66 and PA 9T) were exposed to various intensities of electron radiation (33 kGy, 66 kGy, 99 kGy, 132 kGy, 165 kGy and 198 kGy). The cross-linked polyamides&rsquo, surface properties were measured by means of the modern nano-indentation technique (Depth Sensing Indentation, DSI), which operates on the principle of the immediate detection of indenter penetration depth in dependence on the applied load. The evaluation was preformed using the Oliver&ndash, Pharr method. The effect of electron radiation on the tested polyamides manifested itself in the creation of a 3D network, which led to an increase of surface layer properties, such as indentation hardness, elastic modulus, creep and temperature resistance, by up to 93%. The increase of temperature and mechanical properties substantially broadens the field of application of these materials in technical practice, especially when higher temperature resistance is required. The positive changes to the nano-mechanical properties as well as mechanical and temperature capabilities instigated by the cross-linking process were confirmed by the gel volume test. These measurements lay the foundation for a detailed study of this topic, as well as for a more effective means of modifying chosen properties of technical polyamide products by radiation.

This article discusses the possibilities of using radiation cross-linked high density polyethylene (HDPEx) acting as a filler in the original high density polyethylene (HDPE) matrix. The newly created composite is one of the possible answers to questions relating to the processing of radiation cross-linked thermoplastics. Radiation cross-linked networking is&mdash, nowadays, a commonly used technology that can significantly modify the properties of many types of thermoplastics. This paper describes the influence of the concentration of filler, in the form of grit or powder obtained by the grinding/milling of products/industrial waste from radiation cross-linked high density polyethylene (rHDPEx) on the mechanical and processing properties and the composite structure. It was determined that, by varying the concentration of the filler, it is possible to influence the mechanical behaviour of the composite. The mechanical properties of the new composite&mdash, measured at room temperature, are generally comparable or better than the same properties of the original thermoplastic. This creates very good assumptions for the effective and economically acceptable, processing of high density polyethylene (rHDPEx) waste. Its processability however, is limited, it can be processed by injection moulding up to 60 wt %.

This article deals with the study of the utilisation of irradiated HDPE products after their end-of-life cycle. Today, polymer waste processing is a matter of evermore intensive discussion. Common thermoplastic waste recycling&mdash, especially in the case of wastes with a defined composition&mdash, is generally well-known&mdash, and frequently used. On the contrary, processing cross-linked plastics is impossible to do in the same way as with virgin thermoplastics&mdash, mainly due to the impossibility of remelting them. The possibility of using waste in the form of grit or a powder, made from cross-linked High Density PolyEthylene (rHDPEx) products, after their end-of-life cycle, as a filler for virgin Low Density PolyEthylene (LDPE) was tested in a matrix. It was found that both the mechanical behaviour and processability of new composites with an LDPE matrix, with rHDPEx as a filler, depend&mdash, to a high degree&mdash, on the amount of the filler. The composite can be processed up to 60% of the filler content. The Polymer Mixture Fluidity dropped significantly, in line with the amount of filler, while the mechanical properties, on the other hand, predominantly grew with the increasing amount of rHDPEx.

This article deals with the influence of electron-beam radiation on the micro-mechanical, thermo-mechanical, and structural properties of selected polymers. In the search for the desired improvement of polymers, it is possible to use, inter alia, one particular possible modification-Namely, crosslinking-Which is a process duringwhichmacromolecular chains start to connect to each other and, thus, create the spatial network in the structure. In the course of the treatment of the ionizing radiation, two actions can occur: crosslinking and scission of macromolecules, or degradation. Both these processes run in parallel. Using the crosslinking technology, standard and technical polymers can acquire the more "expensive" high-tech polymeric material properties and, thus, replace these materials in many applications. The polymers that were tested were selected from across the whole spectra of thermoplastics, ranging from commodity polymers, technical polymers, as well as high-performance polymers. These polymers were irradiated by different doses of beta radiation (33, 66, 99, 132, 165, and 198 kGy). The micro-mechanical and thermo-mechanical properties of these polymers were measured. When considering the results, it is obvious that irradiation acts on each polymer differently but, always when the optimal dose was found, the mechanical properties increased by up to 36%. The changes of micro-mechanical and thermo-mechanical properties were confirmed by structural measurement when the change of the micro-hardness and modulus corresponded to the crystalline phase change as determined by X-ray and gel content. © 2018 by the authors., CZ.1.05/2.1.00/19.0376; National Landcare Programme; MEYS, Ministry of Education, Youth and Science; ERDF, European Regional Development Fund; IGA/FT/2018/012, European Regional Development Fund under the project CEBIA-Tech Instrumentation [CZ.1.05/2.1.00/19.0376]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Program project [LO1303 (MSMT-7778/2014)]; Internal Grant Agency of TBU in Zlin [IGA/FT/2018/012]

To obtain the deeper knowledge about the mechanical behaviour of 3D printed polymeric materials it is necessary to study the material properties from the beginning to the end. The commonly processed polymeric materials (via injection moulding etc.) are already deeply studied and evaluated, but 3D printed specimens in the various orientation build are not yet. In this study the tensile impact test specimens were fabricated via a desktop material extrusion 3D printer Zortrax M200 processing ABS and HIPS in build orientation XY. The 3D printed tensile impact test specimens were examined to compare the effect of layer thickness. Impact pendulum Zwick HIT50P was used for tensile impact tests according to ISO 8256 standard. Optical microscopy was utilized to perform fractography on impact test specimens to explore the effect of the layer thickness on the fracture surface morphology of the failed specimens. This study demonstrates the need for material testing for specific processing as additive manufacturing technologies. © 2018 The Authors, published by EDP Sciences., TBU in Zlin [IGA/FT/2018/012]; Czech Ministry of Industry and Trade in Program "Aplikace" [CZ 01.1.02/0.0/0.0/16_084/0009949]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [L01303 (MSMT-7778/2014)]; European Regional Development Fund under the project CEBIA-Tech [CZ.1.05/2.1.00/03.0089]

This study deals with the multiaxial behaviour of reinforced polypropylene with 30 % of glass fibre (PP30GF) and virgin polypropylene (PP). The impact behavior of these two materials is very needed to know for the possible modification of these two materials to obtain the better material properties. The injection moulded PP, and PP30GF samples were subjected to the penetration test at different set potential energies, and the results were subsequently evaluated and discussed. It was found out that PP has better behaviour at the multiaxial stress than PP30GF. It is possible to claim that for the application more demanding to the impact loading, pure PP is more suitable choice of the polymeric material. © 2018 The Authors, published by EDP Sciences., TBU in Zlin [IGA/FT/2018/012]; Czech Ministry of Industry and Trade in Program "Aplikace" [CZ 01.1.02/0.0/0.0/16_084/0009949]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [LO1303 (MSMT-7778/2014)]; European Regional Development Fund under the project CEBIA-Tech [CZ.1.05/2.1.00/03.0089]

Some polymers need a cross-linking agent for the controlled cross-linking process of polymers with a tendency to degradation during the radiation cross-linking process. While, on the other hand, other polymers do not need a cross-linking agent-predominantly there are cross-linking polymers. The Thermo-Plastic Elastomer (TPE) that was used belongs to this group of predominantly cross-linking polymers; however, this agent is added because of faster reaction times and smaller irradiation doses. Microindentation-tensile and tensile impact tests were carried out on a thermoplastic sample-with, and without, a cross-linking agent. Small changes were measured between these materials at low radiation doses, (up to 66 kGy); nevertheless, at higher doses, the influence of the cross-linking agent on the mechanical properties is significant. © 2018 by the authors., European Regional Development Fund under the project CEBIA-Tech Instrumentation [CZ.1.05/2.1.00/19.0376]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [LO1303 (MSMT-7778/2014)]; Tomas Bata University (TBU) in Zlin [IGA/FT/2018/012]

The presented article deals with the research of micro-mechanical properties in the surface layer of modified Polypropylene filled by 25% of glass fibers. These micro-mechanical properties were measured by the Depth Sensing Indentation - DSI method on samples which were non-irradiated and irradiated by different doses of the β - radiation. Radiation doses used were 0, 66 and 99 kGy for filled Polypropylene with the 6% cross-linking agent (triallyl isocyanurate). The change of micromechanical properties is greatly manifested mainly in the surface layer of the modified polypropylene where a significant growth of microhardness values can be observed.

Bonding has experienced an enormous expansion in the various applications during the last few years in the field of material joining, due to which it is classified as a new joining technology, although it is, in fact, very old. Compared with the conventional joining methods (riveting, screwing and welding), bonding provides a new material combination possibilities and it allows us to obtain special shapes and properties, which can not be formed by conventional methods. To create a high-quality bonded joint, it is important to wet the bonded surface very well wetted by a wetting liquid. The wettability of the material is characterized by a contact angle of wetting, by which the surface energy is subsequently determined. For a high quality of the joint, the bonded material must have higher surface energy than the witting liquid (adhesive) [1-3]. This paper describes the effect of plasma surface treatment on the surface properties (surface energy, microhardness) of low-density polyethylene (LDPE) and high-density polyethylene (HDPE), and also on the final strength of bonded joints. The measured results indicate, that plasma surface treatment is very effective tool for improvement of surface properties and strength of bonded joints of HDPE and LDPE. The strength of bonded joints after plasma surface treatment was increased up to 350 % compared to untreated material. A similar trend was observed even for surface energy and microhardness of materials.

This paper deals with utilization of recycled irradiated high-density polyethylene (rHDPEx) as a filler which was blended with non-modified high-density polyethylene (HDPE). Two blends were tested regarding the original state of the mixing components – HDPE granules/rHDPExgrit and HDPE granules/rHDPExpowder. Results show that the increasing amount of the rHDPEx, regardless its form, results in worsening both observed parameters – hardness and micro-indentation hardness.

The presented article deals with the research of surface layer ́s micro-mechanical properties of modified LDPE by radiation cross-linking after temperature load. These micro-mechanical properties were measured by the DSI (Depth Sensing Indentation) method on samples which were non-irradiated and irradiated by different doses of the β – radiation and then were temperature loaded. The purpose of the article is to consider to what extent the irradiation process influences the resulting micro-mechanical properties measured by the DSI method. The LDPE tested showed significant changes of indentation hardness and modulus after temperature load.

Radiation processing of polymers is a well-established and economical commercial method of precisely modifying the properties of polymers, especially thermo-mechanical properties. The tensile behaviour of modified HDPE samples by radiation cross-linking was measured at the ambient temperature and after temperature load at 220 °C. The tested samples showed significant changes of thermo-mechanical properties and tensile behaviour after 220 °C. From this point of view, new applications could also be seen in areas with service temperatures higher than their former melting point.

In this study there was found that ionizing beta radiation increased the strength of bonded joints and improved the adhesion properties of polypropylene (PP). Generally, for the formation of quality bonded joint it is important to wet the adhesive bonding surface well. Wettability is characterized by the contact angle of wetting. The liquid has to have a lower surface tension than the solid in order to be able to wet the solid substance. The measurement results indicated that ionizing beta radiation was a very effective tool for the improvement of adhesive properties and increased the strength of bonded joints of polypropylene. Bonded surfaces with ionizing beta radiation doses of 0, 33, 66 and 99 kGy were irradiated. The best results were achieved by irradiation at dose of 66 kGy by which the highest surface energy and the highest strength of bonded joints of PP were achieved. The strength of bonded joints after irradiation was increased up to 450 % compared to untreated material. A similar trend was observed even for surface energy.

This research paper deals with an investigation of the fluidity of plastic blends with a recycled filler. Five different blends with three filler concentrations were prepared. As a fillers were radiation crosslinked plastics used. Fluidity was determined by the spiral test where a cavity with the Archimedes spiral is used and a length of the resulting spiral is evaluated and compared. Results show that the more filler is used the worse fluidity there is; however lower concentrations have fluidity almost identical to the non-filled material and the difference is almost negligible. At higher concentrations is the difference more significant and thus it has to be taken into account. Particle size of the filler should be also taken into a consideration but its influence greatly depends on the matrix.

The process of radiation crosslinking helps to improve some mechanical properties of polymer materials. Micromechanical changes in the surface layer of Thermoplastic elastomer (TPE-E) modified by beta radiation were measured by instrumented test of microhardness. The specimens were prepared by injection technology and subjected to radiation doses of 0, 66, 99, 132 kGy. Measurements of microhardness showed considerable changes of behavior of surface layer in middle as well as high radiation doses with higher values of indentation hardness and stiffness.

The process of radiation crosslinking helps to improve some mechanical properties of polymer materials. Micromechanical changes in the surface layer of glass-filled PA-6 modified by beta radiation were measured by instrumented test of microhardness. The specimens were prepared by injection technology and subjected to radiation doses of 0, 66, 99, 132 kGy. Measurements of microhardness showed considerable changes of behavior of surface layer in middle as well as high radiation doses with higher values of indentation hardness and stiffness.

In this study there was found that ionizing beta radiation increased the strength of bonded joints and improved the adhesion properties of polycarbonate (PC). Bonded joints at elevated temperature (60 °C) were tested. Generally, for the formation of quality bonded joint it is important to wet the adhesive bonding surface well. Wettability is characterized by the contact angle of wetting. The liquid has to have a lower surface energy than the solid in order to be able to wet the solid substance. The measurement results indicated that ionizing beta radiation was a very effective tool for improvement of adhesive properties and increased the strength of bonded joints of PC at elevated temperature (60 °C). Bonded surfaces with ionizing beta radiation doses of 0, 33, 66, 99, 132, 165 and 198 kGy were irradiated. The best results were achieved by irradiation at doses of 66 kGy by which the highest surface energy and the highest strength of bonded joints of PC were achieved. The strength of bonded joints after irradiation was increased up to 10 % and surface energy up to 30 % compared to untreated material.

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.

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.

This research paper suggests a possible solution for a growing problem of irradiated materials ́ waste processing. Recycled radiation crosslinked polyamide 6 (rPA6x) 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.

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

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 (rPA6x) 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.

Radiation crosslinking of high-density polyethylene (HDPE) is a well-recognized modification of improving basic material characteristics. This research paper deals with the utilization of electron beam irradiated HDPE (HDPEx) after the end of its lifetime. Powder of recycled HDPEx (irradiation dose 165 kGy) was used as a filler into powder of virgin low-density polyethylene (LDPE) in concentrations ranging from 10% to 60%. The effect of the filler on processability and mechanical behavior of the resulting mixtures was investigated. The results indicate that the processability, as well as mechanical behavior, highly depends on the amount of the filler. Melt flow index dropped from 13.7 to 0.8 g/10 min comparing the lowest and the highest concentration; however, the higher shear rate the lower difference between each concentration. Toughness and hardness, on the other hand, grew with increasing addition of the recycled HDPEx. Elastic modulus increased from 254 to 450 MPa and material hardness increased from 53 to 59 ShD. These results indicate resolving the problem of further recycling of irradiated polymer materials while taking advantage of the improved mechanical properties.

This study deals with high impact polystyrene (HIPS) which was subjected the drop-weight test. HIPS is a polymer produced by the reaction between butadiene synthetic elastomer and styrene (5-14 %) which contains the crystal polymer in certain amounts and is commonly used in mechanical engineering applications where machine parts are exposed to impact loading. The injection moulded HIPS samples were subjected the penetration test at different fall heights and the results were subsequently evaluated and discussed. It was found out that all fall heights are suitable for HIPS penetration, but the optimal one is 50 J because of the smallest variation range. Higher heights are not needed because of increasing power consumption of the test device. From the results, it is clear, that HIPS is not so highly impact resistant material as for example HDPE, because of that is this material suitable for applications where is not often exposed to too big impacts at high velocities. © The Authors, published by EDP Sciences, 2017.

Little research was done to investigate possible utilization of irradiated materials after the end of their lifetime. This research paper deals with the possible utilization of irradiated high-density polyethylene (HDPEx) after its service life. Irradiated HDPE was used as filler into the virgin low-density polyethylene (LDPE). Three material combinations were investigated (powder/powder, granules/powder and granules/grit) and influence of the filler on optical behavior was measured. Terahertz spectroscopy at wide range of frequencies was used for refractive index determination. According to measured data there is significant influence by the amount of the filler. Moreover influence of particle size was also observed. All three combinations have similar curve courses; however the most consistent results were achieved at the powder/powder combination. Behavior of virgin LDPE and virgin HDPE is in correlation with previous findings.