The work is to investigate the effect of the stretching and recovery processes on the microstructure

orientation texture and superstructure of hard elastic polypropylene (HEPP) fibers by FRS XRSA and SAXS.The results show that strain induced crystallization

but when ε ≥30%

X W C approaches a conatant

～90%;strain induced the fragmentation of crystallites;strain induced the lamellae separation in parallel

not induced leaf spring bending

i.e.as ε increases

the orientation distribution of crystallites does not change;when ε≤30%

the lamellae separation is the main process

when ε>30%

the lamellae layers occur fracture and slip along the fiber-axis

thus

before and after ε=30% the atrain mechaniem of the hard elaticity is different;strain-induced microvoids in HEPP

but as ε≥20%

the microvoids'size approaches a definite value.These results have successfully been used to interpret the relationships between the structure and properties of HEPP.