Ming Xiang, Liao-yuan Cai, Ya Cao, Jian Kang, Tong Wu. Manufacturing and Characterization of Polypropylene Separators for Lithium Ion Battery via Biaxially Stretching Method. [J]. Acta Polymerica Sinica (11):1235-1245(2015)
DOI:
Ming Xiang, Liao-yuan Cai, Ya Cao, Jian Kang, Tong Wu. Manufacturing and Characterization of Polypropylene Separators for Lithium Ion Battery via Biaxially Stretching Method. [J]. Acta Polymerica Sinica (11):1235-1245(2015) DOI: 10.11777/j.issn1000-3304.2015.15165.
Manufacturing and Characterization of Polypropylene Separators for Lithium Ion Battery via Biaxially Stretching Method
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.
关键词
聚丙烯二次屈服晶片分布宽度孔径分布均匀性
Keywords
-Nucleated polypropyleneDouble yielding behaviorLamellar thickness distributionPore size distribution