The article deals about the application area of radiation crosslinking of plastics, which follows after the injection moulding. The main objective of the presented article is the research of influence irradiation dosage on mechanical properties of materials: PP filled by 15 % of mineral filler – talc. Mechanical properties - tensile strength and impact strength by Charpy were examined in dependence on absorbed dose of the gamma rays on various conditions and were compared with non-irradiated samples. Radiation processing involves mainly the use of either electron beams from electron accelerators or gamma radiation from Cobalt-60 sources

F. Greškovič

J. Varga

Ľ. Dulebová

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245 METALURGIJA 51 (2012) 2, 245-248F. GREŠKOVIČ, J. VARGA, Ľ. DULEBOVÁTHE UTILIZE OF GAMMA RADIATION ON THE EXAMINATION OF MECHANICAL PROPERTIES OF POLYMERIC MATERIALSReceived – Primljeno: 2011-07-16Accepted – Prihvaćeno: 2011-09-18Preliminary Note – Prethodno priopćenjeISSN 0543-5846METABK 51 (2) 245-248 (2012)UDC – UDK 669.14-418:539.37:620.17=111The article deals about the application area of radiation crosslinking of plastics, which follows after the injection moulding. The main objective of the presented article is the research of infl  uence irradiation dosage on mechanical properties of materials: PP fi  lled by 15 % of mineral fi  ller – talc. Mechanical properties - tensile strength and impact strength by Charpy were examined in dependence on absorbed dose of the gamma rays on various conditions and were compared with non-irradiated samples. Radiation processing involves mainly the use of either electron beams from electron accelerators or gamma radiation from Cobalt-60 sources.Key words: plastics, irradiation, crosslinking, mechanical properties, radiation doseUporaba gama zračenja u ispitivanju mehaničkih svojstava polimernih materijala. U članku je riječ o području primjene zračenja u poprečnom povezivanju polimera, što slijedi nakon injekcijskog prešanja. Glavni je cilj prezen-tiranog članka istražiti utjecaj doze zračenja na mehanička svojstva materijala: PP ispunjen s 15 % mineralnog pu-njenja – milovke. Mehanička svojstva – otpornost na vlak i otpornost na udar po Charpyju bila su ispitivana u ovi-snosti o apsorbiranoj dozi gama zraka u raznim uvjetima te su bila uspoređivana s uzorcima koji nisu bili izloženi zračenju. Radijacijska obrada uglavnom uključuje korištenje drugih elektronskih zraka iz akceleratora elektrona ili gama zračenja iz kobalta 60.Ključne riječi: plastika, zračenje, poprečno povezivanje, mehanička svojstva, doza zračenjaINTRODUCTIONCross-linking of plastics is a term that we meet in many areas and outside the ﬁ  eld of technology too. Ra-diation cross-linking basically improves plastics in three different ways: it gives them better thermal stability, better abrasion resistance and better resistance to chem-ical and mechanical inﬂ  uences [1, 2].The cross-linking of plastics is a chemical process, in which particular molecules of plastics are connected to-gether. In an ideal case, all the molecules will be inte-grated into the above mentioned grid and the process can be activated by radiation in case of many plastics [3].Cross linking will be initiated by irradiating with high energy electron beams or gamma rays.The energy resulting from the irradiation is absorbed by the plastic. The main difference between beta and gamma rays lies in their abilities of penetrating the ir-radiated material [4].Gamma rays have a high penetration capacity. The penetration capacity of electron rays depends on the en-ergy of the accelerated electrons. The process takes place at room temperature and under normal pressure. Irradiation takes place after the moulding process [5]. The most important properties of cross-linking systems F. Greškovič, J. Varga, Ľ. Dulebová – Faculty of Mechanical Engineer-ing, Technical University of Košice, Košice, Slovak Republicare tensibility and elasticity, which also remain under long-time temperature and mechanical loading.The majority of industrial applications of radiation processing are cross-linking of wire and cable insulations, tube, heat shrink cables, composites, moulded products for automotive and electrical industry etc. [6, 7].EXPERIMENTAL WORKMaterial tested in this work was PP Hostacom CR 250 F G61330. Commercial polypropylenes have up to 95 % isotactic content, which means that pendant methyl groups are almost all on the same side of the chain. When polypropylene is exposed to ionizing radiation, free rad-icals are formed and these cause chemical changes [8]. Material PP Hostacom CR 250 F G61330 – is a material, which is ﬁ  lled by 15 % mineral ﬁ  ller – talc. The used material can be found in automotive, electronics, engi-neering and consumer industries [9, 10].To prepare of test samples for the irradiation was necessary to mix granulate materials with different cross-linking agent [11]. It was the type of cross-linking agent. TAIC - Tryallyloxy-1,3,5-triazine.Test samples enriched by cross-linking agent and test samples without cross-linking agent have been pro-duced by injection moulding technology and were used injection mould with replaceable mould boards. Pro-246   METALURGIJA 51 (2012) 2, 245-248F. GREŠKOVIČ et al.: THE UTILIZE OF GAMMA RADIATION ON THE EXAMINATION OF MECHANICAL PROPERTIES …duced test samples were irradiated by gamma radiation in the company BGS Beta-Gamma-Service Gmbh, Saal a.d. Donau, Germany by irradiation dose: 15 kGy and 50 kGy.After irradiation were carried out selected mechani-cal properties:• tensile test,• Charpy impact test.Individual tests of test samples were made in the en-vironment - standard ambient, degradation of material after UV radiance.The test samples were controlled after injection moulding process and after the conditioning time. For evaluation of tensile properties of plastics was made ac-cording to STN EN ISO 527-1, 2 and was used sample type 1A for testing. Tensile test was carried out on ten-sile machine TIRA- test 2300. It was tested in 5 samples of each type of materials in standard ambient and after UV exposure chamber. For evaluation of impact resist-ance of plastics was made according to STN EN ISO 179 – 1. It was tested in 10 samples of each type of ma-terials in standard ambient and after UV exposure cham-ber.The test samples were subjected to the tests without notch. Impact strength test was carried out on Charpy hammer type PSW 60/500. It was tested in 10 samples of each type of materials in standard ambient and after UV exposure chamber.The artiﬁ  cial aging test by ﬂ  uorescent UV lamps were made in the UV chamber according to STN EN ISO 4892-3, exposure time 28 days at 12 hour cycles for all test materials. The test samples after removal of UV chambers were conditioned according to ISO 291:2008. Afterwards, was performed tensile test and impact strength test by Charpy to detect changes in the pro-perties of the materials after artiﬁ  cial aging by UV ﬂ  uo-rescent lamps according to above-mentioned methodol-ogy.ANALYSIS OF THE RESULTSThe graphic dependence of the measured average values of the tensile test of test samples - yield strength of test samples in a standard ambient and degradation in UV chambers, Figure 1.The graphic dependence of the measured average values of relative elongation of test samples in a stand-ard ambient and degradation in UV chamber, Figure 2.The fracture areas of test samples after tensile test without exposure and after degradation in UV chamber were observed on scanning electron microscope JEOL JSM - 7000F, Japan.The fracture areas of test samples of non-irradiated and irradiated materials with different of radiation dose in standard ambient after tensile test were compared, Figure 3. By the inﬂ  uence of cross-linking was observed increasing density of cross-linking. It was created a suf-ﬁ  cient number of networked sites. For all test samples there has been a brittle fracture of testing samples.The spectrum of the chemical composition is shown in Figure 4 conﬁ  rmed on scanning images of test sam-ples in standard ambient the presence of chemical ele-ments.Figure 3   The fracture areas of test samples irradiated by diff  erent radiation dose a) test sample non irradiated, b) test sample – 15 kGy, c) test sample – 50 kGyFigure 2   Relative elongation of test samples with diff  erent irradiation doseFigure 1   Tensile strength of test samples with diff  erent irradiation dose247 METALURGIJA 51 (2012) 2, 245-248F. GREŠKOVIČ et al.: THE UTILIZE OF GAMMA RADIATION ON THE EXAMINATION OF MECHANICAL PROPERTIES …Figure 6   The spectrum of the chemical composition of tested material after degradation in UV Chamber a) test sample non irradiated, b) test sample – 15 kGy, c) test sample – 50 kGyFigure 5   The fracture areas of test samples irradiated by diff  erent radiation dose after degradation in UV chamber, a) test sample non irradiated, b) test sample – 15 kGy, c) test sample – 50 kGy µFigure 4   The spectrum of the chemical composition of tested material in standard ambient a) test sample non irradiated, b) test sample – 15 kGy, c) test sample – 50 kGyThese were the elements of the polymer - A label, the elements of ﬁ  ller - B label and the elements of cross-linking agent (TAIC) - label C.The fracture areas of test samples of non-irradiated and irradiated materials with different of radiation dose after degradation in UV chamber after tensile test were compared, Figure 5.As in the previous case, it is possible to observe a sufﬁ  cient number of networked sites. Primary radicals are created, that react together in the subsequent chemi-248   METALURGIJA 51 (2012) 2, 245-248F. GREŠKOVIČ et al.: THE UTILIZE OF GAMMA RADIATION ON THE EXAMINATION OF MECHANICAL PROPERTIES …cal reaction. It was created expected connection called link.The spectrum of the chemical composition is shown in Figure 6 conﬁ  rmed on scanning images of test sam-ples after degradation in UV chamber the presence of chemical elements. These were the elements of the pol-ymer - A label, the elements of ﬁ  ller - B label and the elements of cross-linking agent (TAIC) - label C [12].We can state, that the values of tensile strength and relation elongation were inﬂ  uenced by irradiation dose – Figures 1, 2.After tensile test with material Hostacom CR G61330 250 F G61330 by test samples in standard am-bient was found increasing tendency of tensile strength and relation elongation.The value of tensile strength achieved increasing tendency by irradiated test samples in standard ambi-ent against the base material about 10 %. By irradiated test samples after degradation in UV chamber were achieved the values of tensile strength decreasing ten-dency. These values were inﬂ  uenced by irradiation dose about 10 – 15 %.Irradiated test samples in standard ambient had against non-irradiated material progressive tendency of relative elongation.These values were inﬂ   uenced by irradiation dose about 25 – 50 %. Irradiated test samples after degradation in UV chamber had against non-irradiated material de-creasing tendency of relative elongation. These values were inﬂ  uenced by irradiation dose about 25 – 75 %.The graphic dependence of the impact resistance of test samples with different irradiation dose, Figure 7.Figure 7   Impact resistance of test samples with diff  erent irradiation doseCONCLUSIONObtained knowledge in this paper are only parts of the general problem of possible applications of plastics cross-linking. As the automotive industry using a wide range of plastics, it would be suitable to extend the ex-periments to other materials and monitoring of other properties such as:•   bonding – gluing and coating (adhesion improve-ment),•   the inﬂ  uence on welding property,•    thermo-analyses, recycling of cross-linked plas-tics.AcknowledgementsThis paper is the result of the project implementa-tion: Center for research of control of technical, envi-ronmental and human risks for permanent development of production and products in mechanical engineering (ITMS:26220120060) supported by the Research &De-velopment Operational Programme funded by the ERDF and KEGA 263-049TUKE-4/2010.REFERENCES[1]  Z. Brocka, Strahlenvernetzte Kunstoffe Verarbeitung, Ei-genschaften, Anwendung, Springer VDI Verlag, Düssel-dorf. 2006, pp. 1 – 30.[2]  D. Manas, M. Manas, M. Stanek, M. Danek, Materials Science and Engineering, 32 (2008), 2, 69-76.[3]  A. Zyball, Radiation Processing of Polymers. In: Emer-ging applications of radiation processing, IAEA-TE-CDOC-1386, Vienna, 2004 pp. 117–125.[4]  Gamma irradiatiors for radiation processing, International atomic energy agency, Vienna, Austria, pp.1 – 40.[5]  B. Tauzin, L. Hermitte, S. Ponsart, European Cells and Materials 11 (2006), 2, 34.[6]  I. Pucić, Polimeri, 30 (2009), 4, 193 – 204.[7]  Kunstoff Magazin: Hart im Nehmen Strahlenvernetzung für hohe Temperaturen, 2009, pp. 46 – 47.[8]  J. G. Drobny, Radiation Technology for polymers, New York. New York. 2003, pp. 63 – 85.[9]  S. Shukushima, H. Hayami: Radiation Physics and Chemi-stry, 60 (2001), 4 - 5, 489 – 493.[10]  R. J. Woods, A. K. Pikaev: Applied Radiation Chemistry: Radiation Processing, New York. New York, 1994, pp. 13 – 20.[11]  D.W. Auhl, Molekulare Struktur und rheologische Eigen-schaften strahlenmodiﬁ  zierter Polypropylene, Dissertati-on, Universität Erlangen-Nürnberg, 2006, pp. 56 – 65.[12] J.  Varga,  The  inﬂ  uence of radiation crosslinking on mecha-nical properties of plastic parts, PhD thesis, Košice, 2009, pp. 100 – 140.Note:   The responsible for English language is Helena Mazúrová, Tech-nical University of Košice.On the basis of the experimental results could be formulated these results:•    At the material Hostacom CR G61330 250 F G61330 is not explicit inﬂ  uence of radiation dose to the impact resistance.•   The increasing tendency of value was recorded in irradiated test samples after degradation in UV chamber.•   The highest values of parameter of irradiated test samples were evaluated at 50 kGy radiation dose.

The utilize of gamma radiation on the examination of mechanical properties of polymeric materials

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