The values of 𝑘 𝑑 for the low-density CDA foams were the greatest reported for any plastic evaluated under environmentally relevant marine conditions (Figure ). Moreover, the values of 𝑘 𝑑 for the low-density CDA foams were more than quadruple that of paper and 100 to 1000 times greater than those of solid PP, PS, and PLA. As evidenced for PS, it is expected that foaming will not increase the value of 𝑘 𝑑 for solid plastics with 𝑘 𝑑 less than ~10 µm/yr (i.e., PP and PLA in the marine environment).