Wyniki wyszukiwania - Biblioteka Nauki

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Evaluation of polymers designed for radiation processing

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Przybytniak G. , Nowicki A. , Mirkowski K.

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tom Vol. 53, suppl. 2

67--72

EN

Five types of commercially available polyethylene (PE) and some selected blends with components supporting cross-linking were radiation cross-linked. Mechanical properties and gel fraction were determined upon electron beam irradiation to such a dose that induces about 60% gel fraction. It was confirmed that for easily cross-linked PEs strength at break usually was growing and for polyethylenes less susceptible to radiation cross-linking – was reduced. Similar dependence was found for elongation at break. It was confirmed that for polyethylenes demonstrating high strength at break the efficiency of radiation cross-linking is limited. Additionally, for selected polymeric materials, stress relaxation and accelerated thermal aging were estimated. In order to enhance cross-linking yield some blends with EVA copolymer (ethylene-vinyl acetate) were prepared. On the basis of the literature data, the influence of crystalline regions on cross-linking and mechanical properties was discussed as well.

2

Model studies on phenolic antioxidant role in radiation - and thermally - induced accelerated degradation of electrical cable insulation

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Boguski J. , Przybytniak G. , Mirkowski K.

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tom Vol. 57, No. 4

485-489

EN

The main objective of this work was to establish a correlation between radiation- and thermally-induced changes in polyethylene and the amount of compounded phenolic antioxidant (Irganox 1035). Radiation yield of oxygen consumption, oxidative induction time and gel fraction allowed to estimate the utility of the applied experimental methods to monitor oxidative aging of the polymeric material from the standpoint of cable and wire degradation in nuclear power plants. It was found that the phenolic antioxidant not only inhibits chain oxidation but also changes the mechanisms of radical processes influencing significantly capability of polyethylene towards thermally-induced cross-linking.

3

Próby modyfikacji włóknotwórczego poli(tereftalanu etylenu) metodą radiacyjną

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Legocka I. , Mirkowski K. , Nowicki A.

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tom Vol. 50, nr 23

381-384

PL

Podjęto próbę modyfikacji włóknotwórczego poli(tereftalanu etylenu) PET mającą na celu zmianę jego właściwości powierzchniowych stosując promieniowanie akceleratorowe (wiązka szybkich elektronów e) oraz szereg związków modyfikujących.

EN

Radiation modification of poly(ethylene terephthalate) was investigated. Several oligomeric hydrocarbon resins nad monomers, such as glycidyl methacrylate and methacrylic acid were selected radiation grafting process. Comparison of structural, surface and mechanical propeties with non modificated poly(ethylene terephthalate) was carried out.

4

Kompozycje polimerowe oparte na LDPE zastosowane do radiacyjnie sieciowanych taśm termokurczliwych

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Zimek Z. , Legocka I. , Mirkowski K. , Nowicki A.

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tom Vol. 50, nr 23

112-115

PL

Przeprowadzono badania nad możliwością opracowania kompozycji na bazie polietylenu niskiej gęstości LDPE sieciujących pod wpływem niższych niż tradycyjnie dawek promieniowania elektronowego a jednocześnie charakteryzujących się odpowiednimi właściwościami przetwórczymi i wytrzymałościowymi.

EN

Heat shrinkable tapes made of irradiated polyethylene have been produced for years. The memory effect of such product is widely used in many industrial applications. Lower dose required in radiation induced cross-linking process and better performances of the final products are scopes of the research at INCT. The effect of electron beam irradiation on blends of the LDPE with ionomer resin (Surlyn) has been investigated. The mechanical, rheological and thermal properties were been examinated.

5

Zastosowanie techniki radiacyjnej do otrzymywania napełniaczy bentonitowych i ich mieszanek z polipropylenem

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Zimek Z. , Przybytniak G. , Nowicki A. , Mirkowski K.

Inżynieria Materiałowa

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2006

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tom Vol. 27, nr 6

1333-1336

PL

Nanonapełniacze stanowią obszerną grupę cząsteczek stosowanych w kompozytach polimerowych i innych tworzywach w celu poprawy ich właściwości. Głównym problemem związanym z ich użyciem w tworzywach polimerowych jest niekompatybilność polimerów i nanonapełniaczy. Cząstki nieorganiczne są hydrofilowe, natomiast większość polimerów ma charakter hydrofobowy. W celu dobrego zdyspergowania napełniaczy w matrycy polimerowej powinny być one zmodyfikowane poprzez wytworzenie hydrofilowej warstwy na ich powierzchni. W przedstawionej pracy badano sposób modyfikacji warstwowych glinokrzemianów typu montmorylonitu występujących w bentonitach. Modyfikacje prowadzono stosując bezwodnik maleinowy i poddając otrzymany materiał napromieniowaniu wiązką szybkich elektronów z akceleratora. Mechanizm modyfikacji montmorylonitu tą metodą zbadano przy użyciu: WAXD, różnicowej kalorymetrii skaningowej, stosując EP R i widma FTIR. Zbadano właściwości mechaniczne kompozytów polipropylenu i modyfikowanych montmorylonitów. Najlepsze właściwości otrzymano dla modyfikowanego bezwodnikiem maleinowym specjalnie oczyszczanego bentonitu.

EN

Nanofillers are a wide range class of particles that are applied to polymeric composites and other materials to improve some of their properties. The main problem in the mixing process of polymers and fillers is incompatibility of these materials. Inorganic compounds are hydrophilic, while main types of polymers are hydrophobic. For good mixing the fillers should be modified to obtain hydrophobic layer at the surface. In recent work we have concentrated our attention on using a new method to modify of layered aluminumsilicates known as montmorillonites and occurred in bentonites. Modification of the different types of bentonite using maleic anhydride and other organic anhydrides as modifying agents and ionizing radiation as a grafting method shows that particles obtained in this process are good fillers for production of nanocomposites on a basis of polypropylene. Mechanism of modification of montmorillonite was tested using FTIR, EP R, WAXD and DSC techniques. The obtained polymeric materials were tested for mechanical. The features of some final materials were better than initial polypropylene. The best mechanical characteristics were obtained for polypropylene filled with modified domestic bentonite ”Special”.

6

Functionalization of polymer surfaces by radiation-induced grafting

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Przybytniak G. , Kornacka E. M. , Mirkowski K. , Walo M. , Zimek Z.

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tom Vol. 53, No. 3

89-95

EN

The mutual radiation grafting of acrylic acid (AAc) onto polyethylene (PE), polypropylene (PP) and polystyrene (PS) films was performed. At first stage of investigations, the influence of ionizing radiation on the trunk polymers was studied, i.e. the level of radicals stable at room temperature and radiation yield of evolved hydrogen were estimated for each polymer. The measurements were carried out using electron paramagnetic resonance (EPR) spectroscopy and gas chromatography (GC), respectively. Radiation yields of radicals as well as hydrogen emission increased in the following order PS < PP < PE. Under comparable conditions, the same relationship was found for the yield of radiation-induced grafting of AAc. A distinct correlation between content of radicals generated by ionizing radiation in polymeric matrices and grafting degree was confirmed for the studied materials. The effect of monomer and inhibitor concentrations on the efficiency of processes were studied as well.