ABSTRACT. The paper presents irradiation of thermoplastic elastomers based on ethylene-vinyl acetate (EVA) and poly(vinyl chloride) (PVC) plasticized with small ionizing radiation doses, in the presence of triallylisocyanurate (TAC), for the purpose of improving their characteristics. Results obtained from the study have shown that by irradiating blends of EVA/PVC in presence of TAC, new materials with improved properties have been obtained, as a result of crosslinking reactions and reorientation of sample particles under the influence of accelerated electrons. The optimal irradiation dose and the optimal TAC concentration can be chosen depending on the composition of each blend and on the applications of the final product. KEY WORDS: EVA, PVC, TAC, irradiation, physico-mechanical properties STUDIU PRIVIND ÎMBUNÃTÃÞIREA CARACTERISTICILOR FIZICO-MECANICE ALE AMESTECURILOR EVA/PVC IRADIATE CU ELECTRONI ACCELERAÞI ÎN PREZENÞADE TRIALILIZOCIANURAT REZUMAT. Lucrarea prezintã iradierea unor elastomeri termoplastici pe bazã de etilen vinil acetat (EVA) ºi policlorurã de vinil (PVC) plastifiatã cu doze mici de radiaþie ionizantã, în prezenþã de trialilizocianurat (TAC), cu scopul de a îmbunãtãþi caracteristicile acestora. Rezultatele obþinute în urma studiului au arãtat cã prin iradierea amestecurilor de EVA/PVC în prezenþa TAC, s-au obþinut materiale cu proprietãþi îmbunãtãþite, ca urmare a reacþiilor de reticulare ºi de reorientare a particulelor probelor sub influenþa electronilor acceleraþi. Doza optimã de iradiere ºi concentraþia optimã de TAC se pot alege în funcþie de compoziþia fiecãrui amestec în parte ºi de utilizãrile produsului final. CUVINTE CHEIE: EVA, PVC, TAC, iradiere, proprietãþi fizico-mecanice ETUDE SUR L'AMÉLIORATION DES CARACTÉRISTIQUES PHYSIQUES ET MÉCANIQUES DES MÉLANGES EVA/PVC IRRADIÉS PAR FAISCEAU D'ÉLECTRONS DANSLA PRÉSENCE DE TRIALLYL ISOCYANURATE RÉSUMÉ. Cet article présente l'irradiation d'élastomères thermoplastiques mélanges à base d'éthylène-acétate de vinyle (EVA) et le chlorure de polyvinyle (PVC) plastifié avec de faibles doses de rayonnements ionisants en présence du triallyl isocyanurate (TAC) afin d'améliorer leurs propriétés. Les résultats obtenus à partir de l'étude ont montré que par l'irradiation des mélanges EVA/PVC en présence de TAC on a obtenu des matériaux avec des propriétés améliorées en raison des réactions de réticulation et la réorientation des particules d'échantillons sous l'influence des électrons accélérés. La dose optimale de radiation et la concentration optimale de TAC peuvent être choisies selon la composition de chaque mélange séparément et selon les utilisations du produit final.

Natural rubber is the most frequently used elastomer worldwide due to its low prices, renewability, non-toxicity and excellent physical properties. Natural rubber is not used as such but in the form of mixtures which generally contain: fillers for reinforcement, plasticizers, crosslinking agents and other ingredients that confer different characteristics to the final product. Reinforcement of elastomers by incorporating fillers is a process of great practical and technological importance that greatly enhances the physical-mechanical properties of the composite material and reduces the cost price. The origin of such mechanical reinforcement has been linked to the interaction between the rubber and filler as well as the homogeneous dispersion of the filler within the polymer matrix. In natural rubber technology, knowledge of the conditions necessary to achieve more efficient natural rubber-filler interactions is improving continuously. The purpose of this article is to determine the influence of different types of mineral or organic fillers on the properties of natural rubber mixtures. The following were determined for the mixtures obtained: curing characteristics, hardness, elasticity, tensile strength, elongation at break and tear strength. The results indicate that both organic and inorganic fillers have led to improved physical and mechanical characteristics.

The most important stage in the rubber processing technology is vulcanization / crosslinking, which confers mechanical and thermal stability to rubbers. During crosslinking, rubber molecules with chain configuration are linked by chemical bridges / bonds, and the rubber mass turns from its plastic mass into an elastic one. This is normally done by sulphur and accelerator for general purpose rubbers. The chemistry of vulcanization is complex and the resulting crosslinks may be mono-, di-, tri-or higher poly-sulphides, with a proportion which is among others largely determined by the vulcanization system, the cure time and the temperature. These compounds and their reaction products could be responsible for cytotoxicity and allergycausing compounds, such as nitrosamines and nitrosatable materials. For these reasons, the aim was to eliminate or reduce toxic ingredients in elaborating and developing crosslinking technologies for natural rubber mixtures, so that the resulting materials may be used in the pharmaceutical or food industry, as well as in manufacturing other rubber goods (toys, various components for footwear, rubber plates, seals and hoses for various purposes, etc.). This paper presents a study on the influence of the vulcanization method on the characteristics of a natural rubber blend. The tested methods have been: (1) with sulphur and vulcanization accelerators, (2) with benzoyl peroxide in the presence of a polyfunctional monomer. Modification of characteristics was analysed depending on the crosslinking method.

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Performance of the electron beam fluidized bed process for disinfection and disinfestation of stored products AIP Conf.

ABSTRACT. This paper presents the obtaining and characterization of new types of polymeric composites based on natural rubber and plasticized starch, crosslinked using peroxide in the presence of a polyfunctional monomer -trimethylolpropane trimethacrylate. Composite variants containing 10 phr, 20 phr, 30 phr, 40 phr and 50 phr starch, respectively were made. Starch was plasticized and then incorporated in natural rubber in the roll mill, and then other ingredients were added; the resulting mixtures were cured in an electrical press. The physicomechanical characteristics of resulting composites depends on the amount of plasticized starch added to the rubber mixture. The results of liquid action on composites show that it depends on the behaviour of mixture components in immersion media; thus, natural rubber is water resistant (variation of mass and volume in water has very low values) but not resistant to toluene (variation of mass and volume in toluene has high values); starch is hydrophilic -it absorbs water and, with the increased amount of starch in the mixtures, there is also an increase of mass and volume variation in water, but the values obtained are good, with mass and volume variation after 22 h of water immersion being below 8%. In toluene, there is an improvement in the behaviour of composites containing plasticized starch compared to control ones (without plasticized starch). The new polymer composites can be used in various fields such as in the food or pharmaceutical areas that require compositions free of toxic ingredients. KEY WORDS: polymer composites, natural rubber, starch, characteristics CARACTERISTICILE UNOR COMPOZITE POLIMERICE PE BAZĂ DE CAUCIUC NATURALREZUMAT. Această lucrare prezintă obţinerea şi caracterizarea unor noi tipuri de compozite polimerice pe bază de cauciuc natural şi amidon plastifiat, reticulate utilizând peroxid în prezenţa unui monomer polifuncţional -trimetilolpropan trimetacrilat. Compozitele au fost realizate cu conţinut de amidon 10 phr, 20 phr, 30 phr, 40 phr şi respectiv 50 phr. Amidonul a fost plastifiat şi apoi încorporat în cauciucul natural pe valţ, după care s-au adăugat celelalte ingrediente; amestecurile obţinute au fost vulcanizate în presa electrică. Caracteristicile fizicomecanice ale compozitelor obţinute depind de cantitatea de amidon plastifiat adăugat amestecului de cauciuc. Rezultatele acţiunii lichidelor asupra compozitelor arată că aceasta depinde de comportarea componentelor amestecului în mediul de imersie; astfel, cauciucul natural este rezistent la apă (variaţia masei şi volumului în apă având valori foarte mici), dar nu este rezistent la toluen (variaţia masei şi volumului în toluen are valori mari); amidonul este hidrofil -absoarbe apa şi, odată cu creşterea cantităţii de amidon din amestecuri, are loc şi o creştere a variaţiei masei şi volumului în apă, însă valorile obţinute sunt bune, variaţia masei şi volumului după 22 h de imersie în apă fiind sub 8%. În toluen se observă o îmbunătăţire a comportării compozitelor care conţin amidon plas...

This transient permeabilized state of the cell membrane, named the "cell electroporation" (CE) can be used to increase cells uptake of drugs that do not readily pass cell membrane, thus enabling their cytotoxicity. The anticancer drugs, such as bleomycin (BL) and cisplatin, are the most candidates for the combined use with ionizing and nonionizing radiation fields. The methods and installations for the cell electroporation by electron beam (EB) and microwave (MW) irradiation are presented. The viability tests of the human leukocytes under EB and MW exposure with/without the BL in the cell cultures are discussed.All biological membranes have a common general structure: each is a very thin film of lipid and protein molecules, held together mainly by noncovalent interactions. Certain membrane transport processes can be modified when the cell membrane bilayer viscosity is experimentally increased or decreased by applying different external physical energies such as EB and MW energy. The goal of our work was to find appropriate and necessary physical parameters of the applied EB and MW fields and cell cultures that perform destabilized cell membranes: more-permeable state of the cell membranes in order to increase cells uptake of drugs.EB and MW exposure experiments were carried out with originals experimental arrangements consisting mainly of an electron linear accelerator of 6.23 MeV and 75 mA and a 2.45 GHz generator of adjustable MW output power. Fig. 1 presents the effects of EB irradiation or/and bleomycin on leukocytes survival fraction: EB exposure of 0.5 Gy increases BL cytotoxicity by a factor of 1.39 for 7.5 |oM belomycin and 1.91 for 30 \xM bleomycin, respectively. Fig. 2 shows that 5 minutes and 25 minutes MW exposure at SAR of 25 W/kg increases BL (30 |aM) cytotoxicity by a factor of 1.28 and 1.7, respectively. CP899, Sixth International Conference of the Balkan Physical Union, edited by S. A. Cetin and I. Hikmet © 2007 American Institute of Physics 978-0-7354-0404-5/07/$23.00 ] Control sample ] Irradiated sample with EB of 0.5Gy ; o.8H | 0.2f| i o.o 7.5 Bleomycin (uJVl) FIGURE 1. The effects of EB irradiation or/and bleomycin on leukocytes survival fraction. Q^ 0 minutes MW irradiation Q^ 5 minutes MW irradiation ^H 25 minutes MW irradiation 0 fiL 30 ^L Bleomycin "S. 0.2 FIGURE 2. The effects of 5 and 25 min. MW irradiation or/and bleomycin upon leukocytes survival fraction. Transient and reversible permeabilization of the cell membrane can be induced by EB and MW exposure depending on the cell exposure level. 816

The goal of the paper is to present the obtaining, characterization and testing of a new type of polyelectrolyte based on acrylamide, acrylic acid and sodium alginate for flocculation purposes. Polyelectrolytes, also called flocculants, were obtained by electron beam irradiation in atmospheric conditions and at room temperature. They have been characterized using various physical and chemical methods in order to determine conversion coefficient, residual monomer content, intrinsic viscosity and molecular weight. The heavy metals removal (Cu 2+ and Cr 6+) was evaluated at room temperature on synthetic water having the contents of 0.05 wt/vol % CuSO4 and 0.05 wt/vol % K2Cr2O7, respectively.