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Polymers 2016, 8(9), 329;

Cracks in Polymer Spherulites: Phenomenological Mechanisms in Correlation with Ring Bands

Department of Chemical Engineering, National Cheng Kung University, No. 1, University Road, Tainan 701-01, Taiwan
Author to whom correspondence should be addressed.
Academic Editor: Alexander Böker
Received: 18 July 2016 / Revised: 24 August 2016 / Accepted: 30 August 2016 / Published: 2 September 2016
(This article belongs to the Collection Featured Mini Reviews in Polymer Science)
PDF [24685 KB, uploaded 2 September 2016]


This article reviews possible mechanisms of various crack forms and their likely correlations with interior crystal lamellae and discontinuous interfaces in spherulites. Complex yet periodically repetitive patterns of cracks in spherulites are beyond attributions via differences in thermal expansion coefficients, which would cause random and irregular cracks in the contract direction only. Cracks in brittle polymers such as poly(l-lactic acid) (PLLA), or poly(4-hydroxyl butyrate) (PHB), or more ductile polymers such as poly(trimethylene terephthalate) (PTT) are examined and illustrated, although for focus and demonstration, more discussions are spent on PLLA. The cracks can take many shapes that bear extremely striking similarity to the ring-band or lamellar patterns in the same spherulites. Crack patterns may differ significantly between the ring-banded and ringless spherulites, suggesting that the cracks may be partially shaped and governed by interfaces of lamellae and how the lamellar crystals assemble themselves in spherulites. Similarly, with some exceptions, most of the cracks patterns in PHB or PTT are also highly guided by the lamellar assembly in either ring-banded spherulites or ringless spherulites. Some exceptions of cracks in spherulites deviating from the apparent crystal birefringence patterns do exist; nevertheless, discontinuous interfaces in the initial lamellae neat the nuclei center might be hidden by top crystal over-layers of the spherulites, which might govern crack propagation. View Full-Text
Keywords: crack patterns; PLLA; ring-banded spherulites crack patterns; PLLA; ring-banded spherulites

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Woo, E.M.; Lugito, G. Cracks in Polymer Spherulites: Phenomenological Mechanisms in Correlation with Ring Bands. Polymers 2016, 8, 329.

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