at the present time. Preliminary X-ray studies of the triblock polymers under stress indicate very marked changes in all of the scattering peaks. However, the interpretation is no longer as simple as in the above experiments.

In a previous paper, the laboratory preparation and properties of phenol-formaldehyde resins employing sodium carbonate and sodium hydroxide as catalysts were presented. In addition, the preparation and properties of highpressure decorative laminates produced from these resins were discussed. In order to extend and amplify the laboratory results, it was necessary to scale up the laboratory experiments. The sodium carbonate catalyzed phenolic resins were prepared in 5-gal resin kettles and evaluated for yield, free formaldehyde content, and water dilutability. Subsequent pilot plant paper treating, pilot plant laminating, and laminate evaluation were conducted. Resin preparation and laminate properties are compared for the sodium carbonate and sodium hydroxide catalyzed systems.

The osmotic pressures of six well‐fractionated samples of polyvinylpyrrolidone were measured in aqueous solution in a Lucite‐block type osmometer. The molecular weights and interaction parameters were determined by employing the theory proposed by Maron for osmotic pressure. It was shown that for all of the fractions, a linear relation existed for ψ and y as predicted by the theory. This new method for expressing osmotic pressure data is compared with the more commonly used expression: It was found that the molecular weights and T2 are in satisfactory agreement. However, the value ofg was not a constant equal to 0.25, but varied with the molecular weight. The expression for the osmotic pressure given by Maron's theory appears to be an accurate and rapid method of converting osmometric data to molecular weights.

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Over 150 elastomer formulations of NR, DPNR, CR, IIR, AU, EU, EO, ECO, SBR, EPM, EPDM and a silicone rubber have been evaluated to identify the most creep resistant materials. Selected data are presented. Three of the best formulations (DPNR compound 15, CR compound 27 and EPDM compound 49) were found to give excellent creep performance extrapolating to less than 28% relative creep for a 15 year service life. As a result of a requirement for 15 year resistance to 25 pphm O3 concentration, EPDM formulation 49 was selected, and pads were molded and compression tested. Because of the O3 resistance of EPDM, there should not be a significant increase in creep rate.