Gamma radiation polyethylene

Crosslinked polyethylene by gamma-radiation Polyethylene with carbonyl group introduced by oxidation... 

Laboratory tests indicated that gamma radiation treatment and cross-linking using triaHylcyanurate or acetylene produced a flexible recycled plastic from mixtures of polyethylene, polypropylene, general-purpose polystyrene, and high impact grade PS (62). 

Solution polyacrylamides can also be prepared at high polymer soHds by radiation processes (80,81). Polyacrylamides with molecular weights up to 20 million can be prepared by inradiation of acrylamide and comonomers in a polyethylene bag with cobalt-60 gamma radiation at dose rates of 120-200 J/kg-h. The total dose of radiation is controlled to avoid cross-linking. 

Photodegradation of polyethylene waste can be markedly accelerated via its grafting with acrylamide [98], In contrast, photostabilization of polyethylene and polypropylene can be achieved as a result of the grafting of 2-hydroxy-4-(3-methacryloxy-2-hydroxy-propoxy) benzophenone using gamma radiation [ 147], In this case, the grafted compound acting as a U V stabilizer is chemically bound to the backbone chain of the polymer and its evaporation from the surface can be avoided. 

Radiolysis Effects. Radicals formed in solvent (SH) and trunk polymers (PH) are important in the grafting of monomers (MH) with gamma radiation. With polymers such as polyethylene, grafting sites are formed by direct bond rupture (Equation 1). Additional sites are also... 

Ready to Sterilize (RtS) Typically components are washed, then rinsed with Water For Injection (WFI) to reduce bioburden and endotoxin levels, lubricated with silicone oil, and finally packaged in a classified area (Classes 100-10,000) in Tyvek bags that can be steam sterilized by the drug or device manufacturer before use. Alternately polyethylene bags may be used if the end user is utilizing gamma radiation for sterilization. 

E. Elshereafy, M.A. Mohamed, M.M. EL-Zayat, A.A. El Miligy. Gamma radiation curing of nitrile rubber/high density polyethylene blends. J. Radioanal. Nucl. Chem. 293, 941-947 (2012)... 

Spadaro, G., Aciemo, D., Dispenza, C., Calderaro, E., Valenza, A., Physical and structural characterization of blends made with polyamide 6 and gamma-irradiated polyethylenes. Radiation Physics and Chemistry 1996, 48(2), 207-216. 

Martinez-Pardo, E., Vera-Graziano, R., Gamma-radiation induced cross-linking of polyethylene ethylene vinylacetate blends. Radiation Physics and Chemistry 1995,45(1), 93-102. 

Experimental studies have shown that vinylene concentration is constant with sample thickness (Costa et al. 1998). Alkyl macroradicals produced by gamma radiation are homogeneously distributed within the UHMWPE component because vinylene are the primary product of interaction between polyethylene and high-energy radiation. In e-beam irradiation, the radical distribution is a function of depth because of the cascade effect, which leads to a subsurface maximum in the absorbed dosage. 

The procedure for neutron measurements involved placing the detector near a neutron source storage drum. Measurements were made with a 3 Ci AmBe neutron source and a 3 mCi Cf spontaneous fission neutron source housed in 55-gallon drums. The drum contained a thick neutron moderator/absorber shield, and, thus, it was assumed that thermal neutrons predominated in the energy distribution outside the drum. The detector and PMT were shielded from fission gamma radiation by 5-cm thick lead bricks, and an additional 3-cm thick, high-density polyethylene moderator was interposed between the bricks and the source drum. Pulse-height spectra were accumulated over 1.5 x 10 s for each sample. 

Buchalla, R. Begley, T.H. Characterization of gamma-irradiated polyethylene terephthalate by liquid-chromato-graphy-mass-spectrometiy (LC-MS) with atmospheric pressure chemical ionization (APCI). Radiat. Phys. Chem. 2006, 75, 129-137. 

Eye ointment tubes should be purchased sterile or should be sterilised. An aluminium tube is generally not resistant to sterilisation by dry heat and limited resistant to steam sterilisation, because the outside lacquer may get sticky. A polypropylene cap and/or cannula of low density-polyethylene are not resistant to sterilisation by dry heat deformation takes place. The resistance to steam sterilisation is very limited. Tubes with plastic parts however can usually be sterilised by gamma radiation. 

We will now move on to a polymer, namely, polyethylene (PE), that is reported to have a very good, as opposed to an excellent, resistance to the effects of gamma radiation. 

It is important to observe that the experimental framework used in this work was designed to allow a comparative study of the mechanical strength properties of non-irradiated and irradiated samples of a specific high-density polyethylene material. Thus, the validity of the data and conclusions obtained is limited by the assumptions and material used. In order to produce more general data, it is desirable to make use of other complementary tests to better characterize the changes in the microstructure of the material due to the application of gamma radiation. 

Luyt [8] also reported that gamma radiation improved the thermal stability of low-density polyethylene. It also influenced Young s modulus and elongation at break, but doses of 150-200 kGy also caused crazing. 

Kaci et al. [14] reported a loss of tensile properties of metallocene linear low-density polyethylene upon exposure to gamma radiation. 

Xiang et al. [13] have studied the effect of gamma radiation on the properties of titanium dioxide-reinforced ultra-high-molecular-weight polyethylene. 

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