High-density polyethylene stress-strain curves

The mechanical properties of PTFE at room temperature are similar to those of medium-density polyethylene, i.e., relatively soft with high elongation, and remaining useful over a wide range of temperatures, from cryogenic (just above absolute zero) to 260°C (500°F) its recommended upper use temperature.28 Stress-strain curves are strongly affected by the temperature however, even at 260°C (500°F) the tensile strength is about 6.5 MPa (942 psi).29... 

Figure 18.6 Isochronous stress-strain curves of various grades of lovv - and high-density polyethylene at 23 (1 hour data). Source Author s own files)...

Differing stress levels have been used for high-density polyethylene and low-density polyethylene for the reasons previously discussed, so an easier comparison between grades can be made by the use of isochronous stress-strain curves. 

Nominal tensile stress versus strain for a low density polyethylene at 150 C rotating clamps, = 0.035 . The highest curve shows the effect of small temperature gradients (> 0.1°C710 cm) at high strain. iMth excellent control of temperature, data are reproducible to within the shaded region. From Meissner et al. (1981). 

---