Limits...
Cascading time evolution of dissipative structures leading to unique crystalline textures.

Hashimoto T, Murase H - IUCrJ (2015)

Bottom Line: The external fields effectively reduce step-by-step the exceedingly large free energy barriers associated with the reduction of the enormously large entropy necessary for crystallization into unique crystalline textures in the absence of the fields.The cascading reduction of the free energy barrier was discovered to be achieved as a consequence of a cascading evolution of a series of dissipative structures.Here the multi-length-scale heterogeneous structures developed in the amorphous precursors play a dominant role in the triggering of the crystallization in the local regions subjected to a large stress concentration even under a relatively small applied bulk stress.

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Affiliation: Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan ; Quantum Beam Science Directorate, Japan Atomic Energy Agency , Tokai-mura, Ibaraki, 1319-1195, Japan ; Professor Emeritus, Kyoto University , Kyoto, 606-8501, Japan.

ABSTRACT
This article reports unique pattern formation processes and mechanisms via crystallization of materials under external flow fields as one of the general problems of open nonequilibrium phenomena in statistical physics. The external fields effectively reduce step-by-step the exceedingly large free energy barriers associated with the reduction of the enormously large entropy necessary for crystallization into unique crystalline textures in the absence of the fields. The cascading reduction of the free energy barrier was discovered to be achieved as a consequence of a cascading evolution of a series of dissipative structures. Moreover, this cascading pattern evolution obeys the Ginzburg-Landau law. It first evolves a series of large-length-scale amorphous precursors driven by liquid-liquid phase separation under a relatively low bulk stress and then small-length-scale structures driven by a large local stress concentrated on the heterogeneous amorphous precursors, eventually leading to the formation of unique crystalline textures which cannot be developed free from the external fields. Here the multi-length-scale heterogeneous structures developed in the amorphous precursors play a dominant role in the triggering of the crystallization in the local regions subjected to a large stress concentration even under a relatively small applied bulk stress.

No MeSH data available.


Related in: MedlinePlus

Average diameters of shishs and kebabs measured with a TEM as a function of total draw ratio ∊ attained by the single-step and/or the two-step hot-drawing of the as-spun fibre.
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fig14: Average diameters of shishs and kebabs measured with a TEM as a function of total draw ratio ∊ attained by the single-step and/or the two-step hot-drawing of the as-spun fibre.

Mentions: The fibres after the single-step or two-step hot-drawing were completely free from solvent. Some of the drawn fibres were picked up to investigate closely under a transmission electron microscope in order to evaluate the average diameters of shishs (DS) and kebabs (DK) using the RuO4 nanoparticles adhering on the surfaces of shishs and kebabs as useful markers. The results are plotted in Fig. 14 ▶ as a function of total draw ratios ∊, ∊ ≡ ∊s for the single-step drawing or ∊ ≡ ∊1∊2 for the two-step drawing, in a double logarithmic scale. It is striking to note that DS hardly changed with ∊, though DK decreased with ∊ to the limiting value close to DS at ∊ ∼ 9, which revealed that the drawn fibre at ∊ ∼ 9 is essentially composed of the shish crystals only and hence the ECC texture (Ohta et al., 2010 ▶).


Cascading time evolution of dissipative structures leading to unique crystalline textures.

Hashimoto T, Murase H - IUCrJ (2015)

Average diameters of shishs and kebabs measured with a TEM as a function of total draw ratio ∊ attained by the single-step and/or the two-step hot-drawing of the as-spun fibre.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4285881&req=5

fig14: Average diameters of shishs and kebabs measured with a TEM as a function of total draw ratio ∊ attained by the single-step and/or the two-step hot-drawing of the as-spun fibre.
Mentions: The fibres after the single-step or two-step hot-drawing were completely free from solvent. Some of the drawn fibres were picked up to investigate closely under a transmission electron microscope in order to evaluate the average diameters of shishs (DS) and kebabs (DK) using the RuO4 nanoparticles adhering on the surfaces of shishs and kebabs as useful markers. The results are plotted in Fig. 14 ▶ as a function of total draw ratios ∊, ∊ ≡ ∊s for the single-step drawing or ∊ ≡ ∊1∊2 for the two-step drawing, in a double logarithmic scale. It is striking to note that DS hardly changed with ∊, though DK decreased with ∊ to the limiting value close to DS at ∊ ∼ 9, which revealed that the drawn fibre at ∊ ∼ 9 is essentially composed of the shish crystals only and hence the ECC texture (Ohta et al., 2010 ▶).

Bottom Line: The external fields effectively reduce step-by-step the exceedingly large free energy barriers associated with the reduction of the enormously large entropy necessary for crystallization into unique crystalline textures in the absence of the fields.The cascading reduction of the free energy barrier was discovered to be achieved as a consequence of a cascading evolution of a series of dissipative structures.Here the multi-length-scale heterogeneous structures developed in the amorphous precursors play a dominant role in the triggering of the crystallization in the local regions subjected to a large stress concentration even under a relatively small applied bulk stress.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan ; Quantum Beam Science Directorate, Japan Atomic Energy Agency , Tokai-mura, Ibaraki, 1319-1195, Japan ; Professor Emeritus, Kyoto University , Kyoto, 606-8501, Japan.

ABSTRACT
This article reports unique pattern formation processes and mechanisms via crystallization of materials under external flow fields as one of the general problems of open nonequilibrium phenomena in statistical physics. The external fields effectively reduce step-by-step the exceedingly large free energy barriers associated with the reduction of the enormously large entropy necessary for crystallization into unique crystalline textures in the absence of the fields. The cascading reduction of the free energy barrier was discovered to be achieved as a consequence of a cascading evolution of a series of dissipative structures. Moreover, this cascading pattern evolution obeys the Ginzburg-Landau law. It first evolves a series of large-length-scale amorphous precursors driven by liquid-liquid phase separation under a relatively low bulk stress and then small-length-scale structures driven by a large local stress concentrated on the heterogeneous amorphous precursors, eventually leading to the formation of unique crystalline textures which cannot be developed free from the external fields. Here the multi-length-scale heterogeneous structures developed in the amorphous precursors play a dominant role in the triggering of the crystallization in the local regions subjected to a large stress concentration even under a relatively small applied bulk stress.

No MeSH data available.


Related in: MedlinePlus