Approved for public release; distribution unlimited. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue and identity by bio Protective coatings, heat transfer, thermal properties, deterioration, heat exchangers, cost-effectiveness. 20. ABSTRACT (Continue on reverse side II necessary and identity by block number;Twelve finned tube heat exchangersfour pieces of three different materials or material combinationswere operated in a marine environment (1) uncoated, (2) coated with an electrostatically applied polyester enamel, (3) coated with a specification alkyd system, or (4) coated with a zinc inorganic silicate material. Temperature drops across each exchanger were monitored for 24 months and heat transfer capacities were calculated for selected periods. Copper tube/ (continued)

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Using a direct weight method, the rate of butadiene polymer growth has been found to be logarithmic with time and proportional to the initial mass of polymer seed present providing active polymer seeds are used. When solutions of potassium sulfide (0.005 and 0.0025 g. per ml.) were added to butadiene, the growth of popcorn polymer in the vapor phase was greatly inhibited. The final weights of 0.100 g. initial polymer seeds were 0.205 and 0.389 g. after 29.6 and 30.5 days at 60°C. respectively, for the two sulfide concentrations. This is to be compared with a normal growth of 2.85 g. after 13.5 days at 60° for a non‐sulfided test. Water does not inhibit popcorn polymer growth and may possibly accelerate it. The activity of the popcorn seeds for spontaneous growth in the presence of monomer depends on the seed generation or extent to which the seeds have grown. The growth activity of a definite mass of polymer increases with continued seed growth until a point is reached where there is a structural change from popcorn‐like to more glassy‐like polymer. The latter has lower growth activity. It is believed that the effect of variation of activity with seed generation is independent of peroxide content and that these tests were performed with peroxide‐free seeds.