SYNOPSISTo improve oil and water repellency, fluorine-containing block copolymers, which were composed of methyl methacrylate (MMA) , glycidyl methacrylate (GMA), and l H , IH, 2H, 2H-heptadecafluorodecyl acrylate (PFA) , were blended with an epoxy resin. It was expected that a glycidyl group would mesh with the epoxy resin by primary bonding, and the low surface energy fluorocarbon segment would absorb and orient to the exterior to fluorinate the surface. X-ray photoelectron spectroscopy, contact angle, and peel strength of pressure-sensitive adhesives for modified epoxy resin surface were determined. The amount of fluorine obtained via angular-dependent ESCA investigation in the modified resin surfaces increased with the shallowing of the sampling depth. With increasing modifier content, the amount of fluorine in the modified resin surface layer increased, and the critical surface tension of modified resin surfaces and the peel strength of a silicone pressuresensitive adhesive affixed to the modified epoxy resin, decreased. A considerable amount of fluorine in the resin surface modified with GMA-containing block copolymers remained after Soxhlet extraction, whereas in the surface modified with copolymer without GMA, more fluorine was extracted. It was shown that these copolymers were good surface modifiers to improve oil and water repellency. 0 1993 John Wiley & Sons, Inc.

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In order to provide a numerical tool for the analysis of pressure response to steam bubble-collapse in a BWR pressure suppression system, a computer program has been developed. The program is featured in the capability of handling three•dimensional fluid structure interaction based on finite element method. Numerical results are compared with experiments in both frequency and time domains. Natural frequencies of the fluid structure system are well predicted. Fluid damping associated with the bubble collapse and pressure wave travelling needs further investigation.

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