Correlation of Structure Changes in the Water-Induced Phase Transitions of Poly(ethylenimine) Viewed from Molecular, Crystal, and Higher-Order Levels As Studied by Simultaneous WAXD/SAXS/Raman Measurements

Hashida, Tomoko; Tashiro, Kohji; Ito, Kazuki; Takata, Masaki; Sasaki, Sono; Masunaga, Hiroyasu

doi:10.1021/ma9017857

Cited by 14 publications

(15 citation statements)

References 23 publications

(65 reference statements)

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“…3d as a solid black trace. Here we find characteristic CH 2 stretches from the interfacial PEI consistent with expectation 23 – 26 . Upon curing, the sharp CH 2 vibrations disappear, and a new dominant peak appears at ~2900 cm −1 (red trace).…”

Section: Resultssupporting

confidence: 88%

Additive manufacturing of strong silica sand structures enabled by polyethyleneimine binder

et al. 2021

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Binder Jet Additive Manufacturing (BJAM) is a versatile AM technique that can form parts from a variety of powdered materials including metals, ceramics, and polymers. BJAM utilizes inkjet printing to selectively bind these powder particles together to form complex geometries. Adoption of BJAM has been limited due to its inability to form strong green parts using conventional binders. We report the discovery of a versatile polyethyleneimine (PEI) binder for silica sand that doubled the flexural strength of parts to 6.28 MPa compared with that of the conventional binder, making it stronger than unreinforced concrete (~4.5 MPa) in flexural loading. Furthermore, we demonstrate that PEI in the printed parts can be reacted with ethyl cyanoacrylate through a secondary infiltration, resulting in an increase in flexural strength to 52.7 MPa. The strong printed parts coupled with the ability for sacrificial washout presents potential to revolutionize AM in various applications including construction and tooling.

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Section: Resultssupporting

confidence: 88%

Additive manufacturing of strong silica sand structures enabled by polyethyleneimine binder

et al. 2021

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“…In many polymers, the phase transition occurring in the crystalline region is known to affect the higher-order structure composed of the crystalline and amorphous phases. − The present PHB case is one of them. ,− Once we know the details of the crystal structural change, the discussion becomes possible about the relation between the structural change in the crystalline region and the higher-order structural change.…”

Section: Resultsmentioning

confidence: 99%

X-ray Crystal Structure Analysis of Poly(3-hydroxybutyrate) β-Form and the Proposition of a Mechanism of the Stress-Induced α-to-β Phase Transition

Phongtamrug

Tashiro

2019

Macromolecules

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The crystal structure of poly(3-hydroxybutyrare) β crystal form has been analyzed on the basis of two-dimensional X-ray diffraction data. The all-trans zigzag chains are packed in the hexagonal unit cell of a = b = 9.22 Å, c (chain axis) = 4.66 Å, and γ = 120° with the space group P3221. The upward and downward chains are statistically located at one lattice site at 50% probability. By combining the thus-analyzed structure information of the β-form with the previously reported structure information of the α-form, the geometrical relation between these two crystalline phases has been clarified in detail. The tension-induced α-to-β phase transition affects the higher-order structural change, as known from the small-angle X-ray scattering (SAXS) data collected in the tensile deformation process. By analyzing all experimentally obtained wide-angle X-ray diffraction and SAXS data, the following transition model has been proposed: the high tension to the oriented sample causes the increase of the long period of the α-form lamellae. As the tensile force is increased, the local stress concentration starts to occur at the short tie chain segmental parts in the amorphous region sandwiched between the stacked lamellae. These highly tensioned tie chains induce the α-to-β structural change in both amorphous and directly connected crystalline regions and generate the 40 Å-wide bundles of zigzag chain segments passing through several neighboring lamellae along the draw direction. These bundles are repeated with the averaged period of about 90 Å in the lateral direction perpendicular to the draw axis. Further stretching causes the cut of the highly tensioned extended chain parts, resulting in the formation of voids and finally the breakage of the whole sample before the completion of the phase transition from the α- to β-form.

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“…Thus, their accurate determinations have been key to revealing the relationship between structure and properties. Generally, they can be determined by atomic force microscopy (AFM) (Mullin & Hobbs, 2011;Savage et al, 2015;Wang et al, 2018) and transmission electron microscopy (TEM) (Rastogi et al, 1997;Maiti et al, 2000;Yamada et al, 2003) in real space, or smallangle X-ray scattering (SAXS) in reciprocal space (Strobl & Schneider, 1980;Hashida et al, 2010;Wang et al, 2014). Compared with AFM and TEM, SAXS has been the most powerful tool to observe structural evolution on the nanoscale, due to its higher time-resolving capability and lower requirements for sample preparation.…”

Section: Introductionmentioning

confidence: 99%

A new small-angle X-ray scattering model for polymer spherulites with a limited lateral size of the lamellar crystals

Li¹,

Ding²,

Liu³

et al. 2019

Int Union Crystallogr J

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As is well known, polymers commonly form lamellar crystals, and these assemble further into lamellar stacks and spherulites during quiescent crystallization. Fifty years ago, Vonk and Kortleve constructed the classical small-angle X-ray scattering theory (SAXS) for a lamellar system, in which it was assumed that the lamellar stack had an infinite lateral size [Vonk & Kortleve (1967), Kolloid Z. Z. Polym. 220, 19–24]. Under this assumption, only crystal planes satisfying the Bragg condition can form strong scattering, and the scattering from the lamellar stack arises from the difference between the scattering intensities in the amorphous and crystalline layers, induced by the incident X-ray beam. This assumption is now deemed unreasonable. In a real polymer spherulite, the lamellar crystal commonly has dimensions of only a few hundred nanometres. At such a limited lateral size, lamellar stacks in a broad orientation have similar scattering, so interference between these lamellar stacks must be considered. Scattering from lamellar stacks parallel to the incident X-ray beam also needs to be considered when total reflection occurs. In this study, various scattering contributions from lamellar stacks in a spherulite are determined. It is found that, for a limited lateral size, the scattering induced by the incident X-ray beam is not the main origin of SAXS. It forms double peaks, which are not observed in real scattering because of destructive interference between the lamellar stacks. The scattering induced by the evanescent wave is the main origin. It can form a similar interference pattern to that observed in a real SAXS measurement: a Guinier region in the small-q range, a signal region in the intermediate-q range and a Porod region in the high-q range. It is estimated that, to avoid destructive interference, the lateral size needs to be greater than 11 µm, which cannot be satisfied in a real lamellar system. Therefore, SAXS in a real polymer system arises largely from the scattering induced by the evanescent wave. Evidence for the existence of the evanescent wave was identified in the scattering of isotactic polypropylene. This study corrects a long-term misunderstanding of SAXS in a polymer lamellar system.

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Correlation of Structure Changes in the Water-Induced Phase Transitions of Poly(ethylenimine) Viewed from Molecular, Crystal, and Higher-Order Levels As Studied by Simultaneous WAXD/SAXS/Raman Measurements

Cited by 14 publications

References 23 publications

Additive manufacturing of strong silica sand structures enabled by polyethyleneimine binder

Additive manufacturing of strong silica sand structures enabled by polyethyleneimine binder

X-ray Crystal Structure Analysis of Poly(3-hydroxybutyrate) β-Form and the Proposition of a Mechanism of the Stress-Induced α-to-β Phase Transition

A new small-angle X-ray scattering model for polymer spherulites with a limited lateral size of the lamellar crystals

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