Using a previously developed simulation model we study the changes in morph
ology of two-dimensional chain crystals caused by annealing. A series of va
rious intermediate crystalline states with different stability exhibiting a
non-monotonous evolution of the internal energy and the degree of local or
der was found. This clearly shows the generic non-equilibrium character of
polymer crystals. Thus, the classification scheme of equilibrium thermodyna
mic phases cannot be used to describe such transient states in polymer crys
tals. At large length scales the structural changes resemble a liquid-like
behaviour while at the same time at small length scales the chains show an
improvement of crystalline order. The term morphogenesis reflects this comp
lex kinetic behaviour. In addition, simulations with constant heating rates
also demonstrate the importance of relaxation processes in polymer crystal
s.