[en] The following polymer materials: (i) isotactic polypropylene, (ii) low-density polyethylene, (iii) blends of polypropylene and polyethylene with various content of polyethylene, and (iv) natural copolymers of polypropylene with the same amount of ethylene as in blends, were irradiated and subsequently investigated using electron spin resonance (ESR) technique. Polymer samples have been irradiated by applying high-energy electrons from 13 MeV linear electron accelerator (LAE 13/9) over the dose range 10-50 kGy. For controlling radiation degradation of polymers (i), radiation sterilization of medical equipment (ii), and evaluation of radiation resistance of the investigated materials (iii), the following dose ranges have been applied: 10-25 kGy, 20-35 kGy, and ∼ 50 kGy, respectively. The nature and the yield of primary radicals has been analyzed as a function of the absorbed dose for different polymer types by means of ESR using a Bruker ESP-300 spectrometer. The yield of peroxy radicals for various polymers and for their different composition has been also evaluated. Based on the ESR results the mechanism of radiation-induced copolymerization of polymers in solid state has been proposed. (author)

[en] Short communications

[en] The radiation resistance polypropylene has been worked out in the Institute of Nuclear Chemistry and Technology, Warsaw. Its properties have been achieved by addition of special substance blocked the radicals arises during irradiation. The material has been attested by the Institute of Pharmaceuticals after a series of chemical, biological and physical investigations needed according to Polish regulations. 2 figs

[en] Radiation technology for production of radiation resistant polypropylene for medical use has been presented. The method consists in radiation induced copolymerization of polypropylene with ethylene and addition of small amount of copolymer of polyethylene and vinyl acetate. The material of proposed composition has a very good mechanical properties and elevated radiation resistivity decided on possibility of radiosterilization of products made of this material and designed for medical use. 3 figs, 3 tabs

[en] Short communication

[en] Short communication

[en] Short communication

[en] The radiation - induced radicals in poly(ethylene terephthalate) - PET composite with polypropylene - PP and polyetherester KPEE have been studied by ESR spectroscopy. In pure PET matrix radicals are not stabilized ar room temperature but in PET/PP composite (19-20% of PP) similarly to pure PP matrix peroxy radicals are recorded at room temperature with the concentrations indicating that radicals formed originally at PT units are stabilized during migration along polymer chain by PP units enabling the formation of peroxy radicals. In contrast, in PET/KPEE composite materials the radical processes are the same as in PET homopolymers. The changes of polymer viscosity in melting state prove that polymer degradation is major radiation effect in the majority of composite materials. (author)

[en] Polypropylene (PP) is used, among other application, for medical devices production. It was applied also for nuclear track membranes and nuclear track filters development beside other materials like polyethylene terephthalate and polycarbonate. The various crystal structure of PP has significant influence on bi-axially oriented PP films 10 μm thick formation, which is suitable to this application. Modified polypropylene (PP-M) has been obtained in the Institute of Nuclear Chemistry and Technology. This material can be used for production any kind of medical devices. Radicals which are form during PP irradiation are located in crystal phase (stable radicals) and amorphous phase (unstable radicals). Those species have fundamental influence on PP properties after irradiation process. The basic properties of PP-M are described in presented lectures. (author)

[en] The gel permeation chromatography, MFR, and ESR techniques were used to study the resistance to radiation, via molecular weight and viscosity determinations, in homopolymeric PP (Malten PJ 601 and PP 401), a propylene/ ethylene copolymer (Malten PJ 330) and PP modified with propylene/ethylene and ethylene/vinyl acetate copolymers (PP Mod MKE 93) each prepared at the INCT, Warsaw. The MKE 93 and Malten PJ 330 were found to be most resistant to fast electrons. Irradiation results in the degradation and simultaneous reduction of poly disparity in the PP examined MFR measurements and GPC gave consistent results. The higher the polypropylene molecular weight, the greater degree of degradation induced. The MKE 93, i.e., PP most resistant to radiation proved suitable for production of radiation-sterilized hypodermic syringes. (author). 15 refs, 6 tabs, 1 fig