Branching and re-orientation of lamellar crystals in non-banded poly(butene-1) spherulites

Kajioka, Hiroshi; Hikosaka, Masamichi; Taguchi, Ken; Toda, Akihiko

doi:10.1016/j.polymer.2008.01.066

Cited by 34 publications

(72 citation statements)

References 24 publications

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“…In our previous papers, we have reported successful confirmation of the predicted square root dependence of m on VD À1 (or V) in terms of the temperature dependence for polyethylene 16 and polybutene-1, 17 irrespective of the higher order structures of banded and non-banded spherulites. For the banded spherulites of polyethylene, the proportional relationship between P and m in eq 1 has also been confirmed.…”

Section: 2mentioning

confidence: 54%

“…[18][19][20] We have recently suggested a splaying instability due to a gradient field of free energy at the growth front and experimentally confirmed the predicted dependence for the case of banded polyethylene spherulites and non-banded polybutene-1 spherulites. 16,17 As the splaying instability of growth front, we have suggested two possibilities of the gradient in free energy at the growth front formed by (1) compositional gradient of non-crystallizing fractions (MullinsSekerka's type 21,22 ) and by (2) pressure gradient due to the difference in densities of the crystal and the melt (SaffmanTaylor's type 23,24 ). The gradient in free energy accelerates the fluctuation of the growth front and the surface tension suppresses the fluctuation; the balance of those two effects determines the critical lateral width, m .…”

Section: 2mentioning

confidence: 99%

“…We have examined the banded spherulites of polyethylene and non-banded spherulites of polybutene-1 in our recent studies. 16,17 The present paper is therefore for the further confirmation of the following proposed mechanism on the banded spherulites of poly(vinylidene fluoride), PVDF.In our proposed modeling of the branching and reorientation of lamellar crystals, we have suggested the possibility of a splaying instability of the growth front as the source of branching; the lateral width of each lamellar crystal is limited at a critical width, i.e., maximum lateral width, above which the crystal splays into branches. After the branching, the branches will be spontaneously re-oriented due to torsional inherent stress in the case of banded spherulites.…”

mentioning

confidence: 99%

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Branching and Higher Order Structure in Banded Poly(vinylidene fluoride) Spherulites

Toda

Taguchi

Hikosaka

et al. 2008

Polym J

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The formation mechanism of banded spherulites of poly(vinylidene fluoride) has been examined experimentally by optical and atomic force microscopies. We have confirmed the proportional relationship between the band spacing and the maximum lateral width of lamellar crystals at the growth front, and the square root dependence of the maximum width and the band spacing on the growth rate. The square root dependence suggests a splaying instability of the growth front regulated by a gradient of free energy in the liquid side, and the proportional dependence suggests the dominant effect of torsional reorientation on the occasion of splaying in the period determination of band spacing.KEY WORDS: Spherulites / Poly(vinylidene fluoride) / Branching / Crystallization of polymers from the melt evolves as a higher-order structure of spherulite with radiating and space filling branches. A number of polymer spherulites accompany concentric ring pattern in them and are called banded (or ringed) spherulite. The formation mechanism of spherulites in general and that of banded spherulites specifically have been studied for many years, but the fundamental mechanism of the pattern formation has not been clarified yet. 1,2The concentric ring pattern in polymer spherulites is caused by an optical birefringence of lamellar crystallites which have twisting correlation along the radial axis.3-10 Concerned with the origin of the torsional stress, folded chains in the upper and lower surface regions of lamellar crystals are supposed to give rise to a residual asymmetric stress which has non-zero component of the torsional stress. The stress is called unbalanced surface stresses 11 and can get stronger by the reorganization of folding surfaces with lamellar thickening.12 The molecular origin of the torsional stress is therefore dependent on the specific nature of each polymer, such as molecular chirality 13 or asymmetric higher-order structures of the crystals. 14,15 In our recent studies, we have been focusing not on the molecular origin of the inherent stress but on the mechanism of the structural formation of spherulites in a mesoscopic scale, i.e., the mechanism of branching and re-orientation of lamellar crystals in the spherulites. We have examined the banded spherulites of polyethylene and non-banded spherulites of polybutene-1 in our recent studies. 16,17 The present paper is therefore for the further confirmation of the following proposed mechanism on the banded spherulites of poly(vinylidene fluoride), PVDF.In our proposed modeling of the branching and reorientation of lamellar crystals, we have suggested the possibility of a splaying instability of the growth front as the source of branching; the lateral width of each lamellar crystal is limited at a critical width, i.e., maximum lateral width, above which the crystal splays into branches. After the branching, the branches will be spontaneously re-oriented due to torsional inherent stress in the case of banded spherulites. Then, the reorientation results in the independent growth...

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Section: 2mentioning

confidence: 54%

Section: 2mentioning

confidence: 99%

mentioning

confidence: 99%

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Branching and Higher Order Structure in Banded Poly(vinylidene fluoride) Spherulites

Toda

Taguchi

Hikosaka

et al. 2008

Polym J

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“…Actually, this could be due to unique crystallization behavior of PB‐1. As seen in Figure , with the growth of the mother crystal, the lateral size increases constantly due to branching . During sequent annealing, more form I nuclei will be formed at the edge of the spherulite.…”

Section: Resultsmentioning

confidence: 96%

In situ POM and FTIR investigation on quiescent phase transition of polybutene‐1 from form II to form I

Ding

Zheng

et al. 2020

Polymer Crystallization

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Despite extensive investigations in the past decade, the factors affecting the phase transition of polybutene‐1 (PB‐1) form tetragonal form II to hexagonal form I were not clarified completely. In this study, quiescent phase transitions of PB‐1 within different morphological of crystals at different temperatures were investigated employing polarized optical microscopy and Fourier transform infrared spectroscopy. Results indicate that the phase transition depends not only on intercrystalline links but also on the lamellar thickness. The phase transition always occurs spontaneously first in thick form II lamellae. The intercrystalline links have opposite effects in the early and later stages. In the early stage, it can promote form I nucleation in some form II clusters, where these clusters were subjected to inward tensions of intercrystalline links. While in the later stage, it retards form I growth since subjecting to outward tensions of intercrystalline links. This study helps to identify more effective method to accelerate forms II‐I phase transition.

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“…In those spherulites of PE, PVDF, iPB1, and iPS, the characteristic length of the interior structures, i.e., the band spacing, P, or the correlation length of patchy pattern, L, was found to be proportional to the lamellar width, l, i.e., the lateral size of the building blocks, at the growth front of the spherulites Kajioka et al 2008),…”

Section: Formation Mechanism Spontaneous Reorientation Of Lamellar Crmentioning

confidence: 97%

Spherulitic Growth in Crystalline Polymers

Toda

2013

Encyclopedia of Polymers and Composites

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The most common higher order structure of crystalline polymers is called spherulite. A spherulite is a polycrystalline aggregate densely filled with thin lamellar crystals and formed by consecutive lamellar branching and reorientation of those crystals in non-crystallographic directions. Polymer spherulites have inner structures characterized by periodic banding or patchy patterns that are created by the reorientation with correlated twisting or in random directions, respectively. The specific reorientation is related to the unbalance of surface stresses caused by the chain folding on the upper and lower basal planes of the lamellar crystals. The branching mechanism is related to the fingering instability of the growth front caused by a gradient in chemical potential ahead of the growth front. The dynamical coupling of the branching and reorientation evolves the spherulitic growth in crystalline polymers.

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Branching and re-orientation of lamellar crystals in non-banded poly(butene-1) spherulites

Cited by 34 publications

References 24 publications

Branching and Higher Order Structure in Banded Poly(vinylidene fluoride) Spherulites

Branching and Higher Order Structure in Banded Poly(vinylidene fluoride) Spherulites

In situ POM and FTIR investigation on quiescent phase transition of polybutene‐1 from form II to form I

Spherulitic Growth in Crystalline Polymers

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