Compression tests
Base polymer specimens were machined to cylinders
with a diameter of 15 mm and a height of 20 mm. The tests
were conducted at T
g +17 C or 102 C. To ensure uniform
temperature, the thermal chamber and each specimen
were held at temperature for 10 min prior to testing. To
achieve full contact of the platen on the sample, a preload
of 1 N was used. The cross-head speed was set at an engineering strain rate of 0.0025 s1. The sample was then
compressed until it exhibited macroscopic failure. Foam
specimens were compressed under nearly identical conditions, except the preload was 0.05 N and the compression
endpoint was set to 95 N, nearly the maximum load for
the 100 N load cell