Heat conduction in highly oriented polyethylene

The enhancement of thermal conductivity in oriented polyethylene was attributed to mechanisms including increased chain alignment along the drawing direction, phonon focusing in the elastically anisotropic crystalline phase, and increased crystallinity.

“The enhancement was attributed to various mechanisms including increased chain alignment along the drawing direction7,14, phonon focusing in the elastically anisotropic crystalline phase15,16, and increased crystallinity12,17.”

Prior mean free path values for oriented polyethylene at around 1 THz are about 80 nm for DR 40 and about 60 nm for DR 6 at 10 K.

“For frequencies around 1 THz, prior values inferred from literature data using the dominant phonon approximation at cryogenic temperatures are ∼80 nm using κ ~ 0.34 Wm−1 K−1 for DR 40 (ref. 73), as estimated using LA specific heat of ∼2.8 × 10−4 J cm−3 K−1 at 10 K using the model described above. This value is comparable to an estimated value of ∼60 nm for DR 6 at 10 K (ref. 16).”