As-spun PEN fibers prepared by melt spinning ranged from 0.5 to 10km/min were treated under different conditions like cold drawing.constrained annealing and hot drawing.Structure changes during the treatment were studied through WAXS and DSC testing.The result shows that during the cold drawing process below Tg

stretching induced crystallization can occur and thus α-form crystal formed in the cold drawn samples whose precursor was spun at low speed.However

when the same precursor was subjected to constrained annealing

its amorphous characterstics remain unchanged even the annealing temperature was 200℃ These results may indicate that the stretching stress is more important than elevated temperature in forming a crystals.The crystalline structure of the hot drawn samples depends significantly on the morphology of the precursor fibers.When the as-spun fiber was prepared at low speed and the fiber structure is predominantly amorphus

hot drawing process will induce a-form crystals.It is observed that the predominant β-form crystals in the as-spun fibers wound at higher speeds were partly transformed into a-form crystals during the hot drawing.And the level of this transition depends on the perfection of the β-form crystal in the precursors.The higher the spinning speed

the more perfect the β-form crystals in the as-spun fibers

and the lower the level of this transition

and accordingly

the more the remainder of the β-form crystals in the hot drawn samples.