Irradiation cross-linking

Plastics are by far the largest group of polymeric materials being processed by electron beam irradiation. Cross-linking of polyolefins, PVC, polyesters, polyurethanes, fluoropolymers, and fiber-reinforced composites is a common practice. 

Irradiation cross-linking of small wires and cables with insulation thickness around 1 mm (0.040 in.) is done under a scanner. The wire or cable is strung between two drums to form a figure eight (see Figure 8.1) and is irradiated on both sides. The dose is controlled automatically by a servolink. 

Radical decay associated with combination of radicd species can result in cross-linking. Such reactions are used commercially to cross-link polyethylene, following irradiation. Cross-linking results in an improvement in the mechanical properties of the material, as is the case in irradiated poiyeth3d ie. It mi t be expected, therefore, that specimens which have been tensile testol under conditions which produce... 

NMR studies of polymers, and magnetic resonance imaging (MRI). In an interesting study, the solid state CPMAS NMR data sets for a pharmaceutical compound were analyzed using DECRA. In these experiments the exponential decay of the signal intensity in the data matrix D decayed as a result of H spin lattice T relaxation. The DECRA results allowed the resolution of two distinct crystalline polymorphs within the compound. DECRA has also used to analyze the C MAS NMR spectra of irradiated cross-linked polyolefin cable insulation. In this study, the two proportional data... 

Urry DW, Parker TM, Reid MC, Gowda DC. Biocompatibility of the bioelastic materials, poly (GVGVP) and its gamma-irradiation cross-linked matrix - summary of generic biological test results. J Bioact Compatible Polym 1991 6 263-282. 

Chemical or irradiation cross-linking of poly(ethylene oxide) resins yield hydrogeb, which are not water soluble but water absorptive, capable of absorbing 25-100 times their own weight of water. These hydrogels are reportedly useful in the manufacture of absorptive pads for catamenial devices and disposable diapers. 

Acrylics (cyanoacrylates anaerobic, by heating or UV-irradiation cross-linking acrylates) for mounting adhesives, sealants, and for adhesive tapes [2,3]... 

The most commonly used adhesives in the electronics industry are thermosetting one-component epoxy resins and UV-irradiation cross-linking acrylates [7]. 

X20 indicates 20 Mrad 7-irradiation cross-linked polymer matrix. 

Ouattara, B., Canh, L.T., Vachon, C., Mateescu, M.A., Lacroix, M. Use of y-irradiation cross-linking to improve the water vapor permeability and the chemical stability of milk protein films. Radiat. Phys. Chem. 63, 821-825 (2002)... 

Figure 2.4. The lefthand side shows a representative sheet of y-irradiation cross-linked elastic-contractile model protein, designed for the conversion of an input energy into the output of pumping iron, per-...

Figure 5.13. A procedure for the formation of elastic model proteins into y-irradiation cross-linked sheets for characterization as elastic-contractile systems for performance of mechemical work of lifting a weight.

The elastic strip or sheet is removed from the tubes, and it is found to swell on lowering the temperature and to contract on raising the temperature through the temperature interval from 20° to 37° C, as depicted at the right in Figure 5.13. A sheet of y-irradiation cross-linked (GVGVP)a5i is shown in Figure 5.14. 

Figure 5.14. Sheet of elastic model protein of y-irradiation cross-linked (GVGVP)25i as demonstrated in Figure 5.13 directly usable in thermally driven contraction and in chemically driven contraction.

A sheet of 20Mrad y-irradiation cross-linked (GVGVP)25i, that is, X "-(GVGVP)25i, is shown in Figure 5.14 and a disk of this material containing a human meteral explant (see Figure 9.36A, below) is used in the simulated urinary... 

In this animal model for strabismus surgery, 20 Mr ad y-irradiation cross-linked poly (GVGVP), X -poly(GVGVP), presented a biocompatible barrier to the formation of adhesions, caused neither an inflammatory response nor the usual foreign body response of fibrous capsule formation, and appeared to be innocuous, its presence being ignored by the host. 

Bioelastic patches or disks are shown in Figure 9.46 for different loading levels of dazmegrel. The circular patches, cross-sectional area of 1.9 cm are 20 Mrad y-irradiation cross-linked (GVGIP)2so, designated as X -(GVGIP)2 o,... 

Figure 9.46. y-Irradiation cross-linked elastic disks of X -(GVGIP)26o, equilibrated in dipropylene glycol/propylene glycol/H20 (2 1 1) and loaded with 0,0.1,1, and lOmg/cm dazmegrel, a thrombox-... 

D.W. Urry, T.M. Parker, M.C Reid, and D.C. Gowda, Biocompatibility of the Bioelastic Materials, Poly(GVGVP) and Its y-irradiation Cross-linked Matrix Summary of Generic Biological Test Results. J. Bioactive Compatible Pofyw., 6,263-282,1991. 

Figure 9. Mechano-chemical coupling by 20Mrad y-irradiation cross-linked of poly[0.8(GVGVP), 0.2(GEGVP)] under isotonic (A) and isometric (B) conditions. In part B under isometric contraction conditions there occurs an increase in entropic elastic force resulting from a decrease in entropy of...

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