Poly electron-beam irradiation effects

Burillo, G., Tenorio, L., Bueio, E., Adem, E., Ixrpez, G.P. Electron beam irradiation effects on poly(ethylene terephtalate). Radiat Phys. Chem. 76, 1728-1731 (2007)... 

Han, S.O., Cho, D., Park, W.H., and Drzal, L.T. (2006) Henequen/ poly(butylene succinate) biocomposites electron beam irradiation effects on henequen fiber and the interfacial properties of biocomposites. Compos. Interfaces, 13, 231-247. 

The incorporation of small percentages (<10%) of 3-oximino-2-butanone methacrylate (4) into poly(methyl methacrylate) (PMMA) (Scheme I) results in a four fold increase in polymer sensitivity in the range of 230-260 nm flO.l 11. Presumably, the moderately labile N-O bond is induced to cleave, leading to decarboxylation and main chain scission (Scheme II). The sensitivity is further enhanced by the addition of external sensitizers. Also, preliminary results indicated that terpolymerization with methacrylonitrile would effect an additional increase. These results complement those of Stillwagon (12) who had previously shown that copolymerization of methyl methacrylate with methacrylonitrile increased the polymer s sensitivity to electron beam irradiation. The mole fraction of the comonomers was kept low in order to insure retention of the high resolution properties of PMMA (3.41. 

Proton nuclear magnetic resonance CH NMR) spectra of the thylene unit in poly(ethylene 2,6-hapthalate) (PEN)/poly(ethylene terephthalate) (PET) blends at various dose rates. (From Kim, J. U. N. Y., Kim, O. FI. S., Kim, S. H. U. N., Jeon, H. A. N. Y., Effects of electron beam irradiation poly(ethylene terephthalate) blends. Polymer Engineering and Science 2004, 44(2), 395-405. With permission.)... 

Kim JY, Kim OS, Kim SH, Jeon HY. Effects of electron beam irradiation on poly(ethylene... 

The effect of electron beam irradiation on the miscible poly(styrene) and poly(vinyl methyl ether) (PVME) blend has been studied. The poly (styrene), being much more resistant to effects of irradiation, does not offer any protectimi to the poly(vinyl methyl ether). Gel content studies indicated significant crosslinking [199]. Further studies of this... 

Therefore, this chapter presents preliminary evidence indicating the effect and interrelationship between primary and secondary molecular motions on thrombogenesis, independent of morphological order and/or crystallinity. The polymer selected for this study was an amorphous elastomeric hydrophobic polymer of poly[(trifluoroethoxy) (fluoroalkoxy)phosphazene] (PNF) I (5, 6). The salient aspects of this polymer are that (1) the onset of the secondary molecular motions occurs between -160° and - 120°C (2) the side chain motion can be altered by irradiation (ultraviolet, electron beam, or gamma) (3) no apparent ultrastructure morphology exists (4) the side chains can be derivatized (5) and (5) the polymer can be readily coated onto our extracorporeal test shafts (7) and irradiated accordingly. Additionally, contact angle measurements of the homopolymer (8) and the PNF (9), 19.7 and 15.0 dyn/cm2, respectively, indicated that the fluorinated side chains comprised the surface to be interfaced in the extracorporeal blood studies. 

Bowden and L.F. Thompson, Electron irradiation of poly(olefin sulfones) Application to electron beam resists, J. Electrochem. Soc. 120, 1722 (1973) Poly(Styrene sulfone) A sensitive ion millahle positive electron beam resist, J. Electrochem Soc. 121, 1620 (1974) D.R. McKean, U.P. Schaedeli, and S.A. MacDonald, Acid photogeneration from sulfonium salts in solid polymer matrices, J. Polym. Set Polym. Chem. Ed. 27, 3927 (1989) D.R. McKean, U.P. Schaedeli, P.H. Kasai, and S.A. MacDonald, The effect of polymer structure on the efficiency of acid generation from triarylsulfonium salts, J. Polym. Sci. Polym. Chem. Ed. 29, 309 (1991). 

Semicrystalline polymers are polymers that contain both crystalline and amorphous states. In general, the major effect of irradiation, either electron beam or y-rays, on the crystalline region is to cause some imperfections. At high levels of irradiation the original crystalline structure tends to be progressively destroyed and is nearly always accompanied by a drop in the crystalline melting point, Tm. An example is that of poly(ethylene terephthalate), which shows a decrease in melting point of approximately 25 °C after irradiation (20 MGy) [51]. 

Elastomers such as cis-l,4-polyisoprene (natural rubber), polybutadiene, polybutadiene-styrene (SBR), and poly-chloroprene have large amounts of unsaturatiOTi in the polymer backbone and aU undergo crosslinking upon irradiation with either electron beam or 7-irradiation. Table 52.3 gives some values for G(X) and the ratio of scission to crossUnk-ing G(S)/G(X) for several elastomers. The protective effect of the aromatic ring is shown by the decrease in yield as the percentage of styrene is increased for the SBR series. 

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