A review is given of the structure of semi-crystalline polymers and th
e mechanisms of plastic deformation in them. High-density polyethylene
(HDPE) is taken as the specific example because of the large number o
f detailed studies performed on this material. The early findings are
also compared and contrasted with very recent detailed large-strain de
formation studies and computer simulations of deformation-induced text
ure development in HDPE.