SynopsisPolyethylene, polypropylene, poly(viny1 fluoride) (Tedlar), polystyrene, nylon 6, poly(ethy1ene terephthalate) (Mylar), polycarbonate, cellulose acetate butyrate, and a poly(oxymethy1ene) copolymer were treated with activated helium and with activated oxygen. Mechanical strengths of adhesive-bonded specimens prepared from treated and from untreated coupons were compared. Polyet.hylene (PE) and polypropylene (PP) showed the greatest increases in bond strength. Oxygen and helium were both effective with polyethylene, but polypropylene showed no improvement when treated with activated helium. The results with excited helium parallel the effects of ionizing radiation on these two polymers, as does the appearance of unsaturation bands in the infrared (965 cm-' in PE, and 887 and 910 cm-1 in PP). Active nitrogen produced excellent bond strength with polyethylene but not with polypropylene. Of the remaining polymers examined, Tedlar, polystyrene, and nylon 6 showed the greatest improvement in bondability after treatment, and Mylar showed moderate improvement. Polycarbonate, cellulose acetate butyrate, and the poly(oxymethy1ene) copolymer gave approximately two-fold increases in lap-shear bond strength. I n several cases, significant differences in response to time of treatment and type of excited gas were found.

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synopsisThe bondability of the following polymers as a function of length of exposure to excited helium or oxygen was investigated: lowdensity polyethylene, highdensity polyethylene (two types), poly(4methyl-l-pentene), poly(viny1 fluoride), poly(vinylidene fluoride), FEP Teflon, poly(oxymethy1ene) copolymer, nylon 6, nylon 66, poly(ethy1ene terephthalate), and polystyrene. Generally, the bond strength increases rapidly initially and then remains nearly constant, perhaps decreasing in some cases a t long exposure times. A method is presented for calculating bond strength-versusexposure time curves. The calculated curves generally fit the data reasonably well. Polypropylene showed a rapid increase in bondability with exposure to excited oxygen. Helium was ineffective toward this polymer under normal conditions, but could produce good bond strength at higher temperatures.

The adsorption of several radioactive ions on aluminum surfaces during the surface treatment of coupons for adhesive bonding was SI +7 studied. These were Cr in the FPL chromic-sulfuric acid etch, and Ca , ^Tfa , Fe ions in the rinse water. Calcium was the most strongly adsorbed ion; manganous and ferric ions showed less than \% monolayer coverage. l^CH-Bisphenol A diglycidyl ether was synthesized from labeled bisphenol A and epichlorohydrin, and used in a room temperature curing adhesive to bond 2024 T-3 aluminum lap shear specimens. Autoradiography was performed on coupons with very thin layers of adhesive remaining after tensile failure of the bonded specimens.