Systematic probing into periodic lamellar assembly via induced cracks in crystallized polyesters

Lee, Ming Syuan; Woo, Eamor M.

doi:10.1016/j.polymer.2019.01.045

Cited by 12 publications

(14 citation statements)

References 23 publications

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“…Earlier, Lee and Woo [ 29 ] already proved that the interior lamellae (i.e., parallel stacks of lamellae) under the ridge band of PHB banded spherulites are indeed normal to the substrate; and conversely, the interior lamellae under the valley band of PHB banded spherulites are horizontal to the substrate. This interior morphology and lamellar architectures are not just in PHB banded spherulites; additionally, Nagarajan and Woo [ 11 ] already proved that 2D SAXS results indicate strongly that the collective fiber axis ( c ‐axis) of crystals in the normal‐oriented lamellae is vertical with the X‐ray beam, leading to 2D signal along the equatorial line with the strongest SAXS intensity; by contrast, the low intensity (or no signal) of SAXS in the equatorial line indicates that the lamellae are horizontal to the substrate (thus, the collective chain axis of the horizontal lamellae is parallel to the X‐ray beam) are perpendicular to the X‐ray beam.…”

Section: Resultsmentioning

confidence: 99%

“…However, investigating the interior structures of the PHB crystal assembly through diluent in order to construct 3D spherulitic structures is still lacking. Lee and Woo [ 29 ] further analyzed the assembly mechanism by interpreting the cooling‐induced cracks in PHB spherulites to expound that the crystallized PHB is assembled from two entities of lamellae oriented in mutually perpendicular intersections (i.e., grating assembly). Because of the discontinuity caused by the grooves/interfaces between successive lamellae or their bundles, cracks tend to occur at the interfaces between the parallel‐assembled crystal bundles in the banded PHB spherulites.…”

Section: Introductionmentioning

confidence: 99%

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Synchrotron X‐Ray Analysis and Morphology Evidence for Stereo‐Assemblies of Periodic Aggregates in Poly(3‐hydroxybutyrate) with Unusual Photonic Iridescence

Liao

Nagarajan

Chuang

et al. 2021

Macromol. Rapid Commun.

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3D morphology of poly(3-hydroxybutyrate) (PHB), crystallized in the presence of diluents of poly(1,3-trimethylene adipate) and poly(ethylene oxide), is probed using a novel approach coupled with selective etching. For interpreting the mechanisms of crystal periodic aggregation, various microscopic techniques and synchrotron microbeam X-ray analysis are used to observe the top surface in connection with the 3D crystal assemblies. Periodic grating architectures, with the cross-bar pitch exactly matching with the optical band spacing, are proved in banded PHB. The crystals under the ridge branch out to spawn finer crystals orienting/bending horizontally underneath the valley band, repeating till species drainage or impingement. The grating structure in the banded PHB resembles many nature's iridescence crystals and is further proved by photonic reflection results as a critical breakthrough novel finding.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synchrotron X‐Ray Analysis and Morphology Evidence for Stereo‐Assemblies of Periodic Aggregates in Poly(3‐hydroxybutyrate) with Unusual Photonic Iridescence

Liao

Nagarajan

Chuang

et al. 2021

Macromol. Rapid Commun.

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“…Note that the actual topology profiles on the banded PBA's top surface might be inherently 2 times greater in depth than what is measured by AFM, because there are very narrow crevices (in the valley bands) not reachable by the AFM probe tip, which has been proven in a recent study. [ 38 ] Thus, the actual height profiles variations in the crystal assemblies might range between 200–300 nm, which falls in the half‐wavelengths of the visible light, [ 39 ] leading to potential photonic crystals with iridescence.…”

Section: Resultsmentioning

confidence: 99%

Microstructural Periodic Arrays in Poly(Butylene Adipate) Featured with Photonic Crystal Aggregates

Nagarajan

Yang

2021

Macromol. Rapid Commun.

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Poly(butylene adipate) (PBA) self‐aggregation into unique periodicity correlating to its interfacial photonic properties is probed in detail. Investigations on the unique periodic morphology and top‐surface and interior architectures in specifically crystallized PBA are focused on its novel photonic patterns with periodic gratings. Detailed analysis of the interior lamellae from ringless to periodically ordered aggregates (crystallized at 33–35 °C vs. Tc = 30 °C) serves as ideal comparisons. Each interior arc‐shape shell is composed of tangential and radial lamellae mutually intersecting at 90o angle. The interior layer thickness in SEM‐revealed arc‐shape shish‐kebab shell is exactly equal to the optical inter‐band spacing (≈6 µm). A 3D assembly mechanism of periodically banded PBA crystals is proposed, where the orderly arrays on top surfaces as well as the interior microstructures of strut‐rib alternate‐layered assembly resemble nature's photonic crystals and collectively account for the interfacial photonic properties in the ring‐banded PBA crystal that is novel and has potential applications in future.

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“…10 Until now, research on individual spherulites is limited. 32 One of the challenges is the lack of experimental methodologies to directly observe the crack behavior at individual spherulite scales.…”

Section: Introductionmentioning

confidence: 99%

Direct observation of the fracture behavior of the polyether ketone ketone (PEKK) spherulites

Marinosci,

Chen,

Helthuis

et al. 2023

J of Applied Polymer Sci

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This article reports the direct observation of the fracture of individual poly‐ether‐ketone‐ketone (PEKK) spherulites. A single layer of PEKK spherulites was obtained by bonding a PEKK film in‐between two sandblasted Ti alloy plates using an autoclave. The crack of an individual PEKK spherulite was achieved by opening the Ti/PEKK/Ti sandwich using a double cantilever beam test. The fracture morphology of the PEKK spherulite was characterized using scanning electron microscopy and atomic force microscopy. It was found that under tensile stress the crack of the individual spherulite propagates along the middle plane and crosses the nucleation core. This is due to the symmetric radial structure of the spherulite. Moreover, it was found that the fracture surface morphology at the core of the spherulite is strongly influenced by the local crystalline structure, which is anisotropic and determined by the initial nucleation growth direction. As a result, the area fraction experiencing plastic deformation during the fracture of PEKK spherulites at different orientations may vary by an order of 10. Our results show the important role of the initial nucleation growth direction on the mechanical properties of the polymer crystals and may provide a new approach to the design of high‐performance polymer materials with tailored crystalline structures.

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Systematic probing into periodic lamellar assembly via induced cracks in crystallized polyesters

Cited by 12 publications

References 23 publications

Synchrotron X‐Ray Analysis and Morphology Evidence for Stereo‐Assemblies of Periodic Aggregates in Poly(3‐hydroxybutyrate) with Unusual Photonic Iridescence

Synchrotron X‐Ray Analysis and Morphology Evidence for Stereo‐Assemblies of Periodic Aggregates in Poly(3‐hydroxybutyrate) with Unusual Photonic Iridescence

Microstructural Periodic Arrays in Poly(Butylene Adipate) Featured with Photonic Crystal Aggregates

Direct observation of the fracture behavior of the polyether ketone ketone (PEKK) spherulites

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