Crystal transformation and micropore formation during uniaxial drawing of β-form polypropylene film

Feng, Cheng; Yamaoka, Tetsuji; Kimura, Yoshiharu

doi:10.1016/0032-3861(95)91197-f

Cited by 80 publications

(64 citation statements)

References 8 publications

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“…It has been suggested that the stress-induced transition between β and α-phase involves a mechanical melting and recrystallization process, since the local arrangement of the 3/1 helical chain segments of different chirality, right-and lefthanded, is much different in the two structures. 37,38 This is in contrast to what happens for i-PBu, in which the transition is not mediated by the amorphous phase, but occurs directly as a solid−solid process (see Figure 5). …”

Section: Methodsmentioning

confidence: 74%

Kinetics of the Polymorphic Transition in Isotactic Poly(1-butene) under Uniaxial Extension. New Insights From Designed Mechanical histories.

et al. 2014

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Isotactic poly(1-butene) (i-PBu) crystallizes upon cooling from the melt in a metastable tetragonal structure (form II), which slowly evolves toward the state of ultimate stability, i.e., the trigonal form I. It is well-known that this polymorphic transformation, which typically requires few weeks at room temperature, can be greatly accelerated by the application of mechanical stresses and/or deformation. However, the exact mechanism of this kinetics enhancement is not completely understood. In this work, the polymorphic transformation of i-PBu under tensile deformation is investigated in details. Thanks to properly designed mechanical histories−including experiments at different true strain and true stress rates−and to in situ wide-angle X-ray diffraction experiments, the role of the various deformation parameters is elucidated. The use of different time scales during the experiments enabled us to gain kinetics data on the transition, information which is disregarded in current literature. The set of experiments performed permit to highlight a stress-driven mechanism, active up to a fraction of transformed form I of about 0.4−0.5. After this value is reached, the stress-transformation time superposition principle does not hold anymore and the transition kinetics slows down, since a major part of the total applied stress is carried by the mechanically stronger form I lamellae.

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Section: Methodsmentioning

confidence: 74%

Kinetics of the Polymorphic Transition in Isotactic Poly(1-butene) under Uniaxial Extension. New Insights From Designed Mechanical histories.

et al. 2014

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“…However, continuous separation of lamellae in equatorial domain is restricted by their lateral rigidity. It may cause violation of continuity of amorphous phase resulting in the formation of the interlamellar nanovoids [29][30][31][32][33][34]. The main question arising from these observations concerns the onset of cavitation.…”

Section: Mechanisms Of Plastic Deformationmentioning

confidence: 99%

Structural mechanics of semicrystalline polymers prior to the yield point: a review

Патлажан

Rémond

2012

J Mater Sci

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The review focuses on the current studies of the deformation response and accompanying structural transformations of thermoplastic semicrystalline polymers subjected to uniaxial tension prior to the yield point. The mechanisms of strain-induced cavitation of amorphous layers and damages of crystalline lamellae are analyzed in line with novel results on the deformation behavior of solid polymers at temperatures exceeding the glass transition point. The coupling of viscoelastic and plastic deformation mechanisms with the small-strain structural transformations is critically discussed on the basis of the advanced theoretical modeling of mechanical properties of semicrystalline polymers.

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“…6a), it is Table 3 The morphological characteristics of the PP-110 and PP-135 after rapid annealing treatments. clear to see that there were few pores in the surface, mainly due to its low stability of β-crystal that would lead to the rapid β-α transformation and the serious shrinkage which consequently reduce the porosity [22][23][24]. Meanwhile, a great number of great pores were observed to distribute randomly in PP-135 membranes (seen in Fig.…”

Section: Stress-strain Behaviors and Performances Of β-Ipp Membranes mentioning

confidence: 90%

“…6c shows that after a sequential biaxial stretching, abundant micropores appeared in PP-110 with T a =135°C, which was consistent with the results of several related studies. Chu [22][23][24] revealed that stable β-crystals in the larger crystallites could hinder the volume shrinkage and enlarge the pores efficiently. Grant [46] also suggested that the porosity of β-iPP under stretching depended on the quantity of perfected β crystalline material in the film.…”

Section: Stress-strain Behaviors and Performances Of β-Ipp Membranes mentioning

confidence: 99%

“…On the other hand, the β-iPP has been widely used to fabricate porous membrane for lithium-ion battery separator through a successively biaxial stretching, for the less dense β-crystal (0.921 g/cm 3 ) is likely to transform into more dense α-crystal (0.936 g/cm 3 ) during stretching, leading to the volume contraction and consequent formation of micropores [17,[22][23][24][25][26][27][28]. However, up to now, the separator made from biaxial stretching of β-iPP is still much poorer than those produced through "dry uniaxial stretch" [29][30][31] and "wet biaxial stretch" [32], leading to the limit of its applications in high tech fields such as power battery.…”

Section: Introductionmentioning

confidence: 99%

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Influence of annealing on stress–strain behaviors and performances of β nucleated polypropylene stretched membranes

Xiang

Cao

et al. 2014

J Polym Res

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In this article, two β nucleated polypropylene (β-iPP) precursor films were prepared through crystallizing at 110 and 135°C. The differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM) and tensile testing were employed to investigate the influence of annealing on stress-strain behaviors and performances of biaxial stretched membranes. The traditional time consuming annealing treatment demonstrates that within the most favorable annealing temperature window of 130-140°C, only a small fraction of thin β lamellae melted and recrystallized to form more stable β phase, resulting in the slight improvement of the stress-strain behaviors and performances of β-iPP membranes. Furthermore, a rapid annealing method was designed, involving a short time thermal stimulus at high temperature and then cooling in the air. During this process, substantial melting and epitaxial crystallization of less stable β crystal occurred, leading to the apparent thickening of β lamellae and the narrowing of β lamellar thickness distribution. Consequently, the stress-strain behaviors of β-iPP films and performances of biaxial stretched membranes were improved significantly.

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Crystal transformation and micropore formation during uniaxial drawing of β-form polypropylene film

Cited by 80 publications

References 8 publications

Kinetics of the Polymorphic Transition in Isotactic Poly(1-butene) under Uniaxial Extension. New Insights From Designed Mechanical histories.

Kinetics of the Polymorphic Transition in Isotactic Poly(1-butene) under Uniaxial Extension. New Insights From Designed Mechanical histories.

Structural mechanics of semicrystalline polymers prior to the yield point: a review

Influence of annealing on stress–strain behaviors and performances of β nucleated polypropylene stretched membranes

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