This manuscript reviews the latest progress to characterize the uniformity of lamellar thickness

the tensile behavior and the uniformity of cavitation during stretching of the casting film

and further to predict the pore size distribution and thickness distribution of the final separator.Five -PP precursor films

which had similar crystallinity and extremely high contents of -crystals

but different lamellar thickness distribution

were prepared through crystallizing at different temperatures.In the tensile test

we first discovered a peculiar double yield phenomenon in -PP under tensile loading.Based on the detailed characterization of morphological evolution during stretching

we concluded that the second yield point corresponds to the transition point where the lamellae began to transform into amorphous phase.Meanwhile

a narrower -lamellar thickness distribution would result in a homogeneous deformation

delayed occurrence of second yield point and a more uniform pore size distribution in the porous membrane.In addition

the stress-strain behaviors of -PP after annealing treatments also verified the trend above.Therefore

the uniaxial tensile testing can be used to evaluate the lamellar thickness distribution of -PP cast films efficiently.