Pilz, Lang
Posters - Additional Information # 2001 Munich
To characterize the viscoelastic properties such as creep modulus and time dependent Poissons’s ratio of commercial medium and high density polyethylene materials (PE-MD, PE-HD), in total 5 types of polyethylene (PE) (pipe grades and non-pipe grades) with densities ranging from 0.928 to 0.951 g/cm3 were investigated. The development and implementation of a suitable test methodology including dynamic mechanical analysis and short-term creep tests combined with proper polymer physics and mechanics concepts allowed for a description of the viscoelastic behaviour of these PE materials over an extended time scale from 10-2 s to 50 years. In good agreement with the results of tests additionally performed on pipe specimens, creep modulus values were found to decrease up to 1.5 orders of magnitude over the time scale indicated. As expected, creep modulus data were found to be strongly affected by the material density. In addition, values for Poisson´s ratio were found to increase with time with short-term values of around 0.4 and extrapolated values approaching 0.5 at 50 years.
