scholarly journals Microstructural Evolution of Poly(ε-Caprolactone), Its Immiscible Blend, and In Situ Generated Nanocomposites

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2587
Author(s):  
Iurii Vozniak ◽  
Ramin Hosseinnezhad ◽  
Jerzy Morawiec ◽  
Andrzej Galeski
Keyword(s):  
Local Stress ◽  
Local Deformation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Immiscible Polymers ◽  
X Ray Scattering ◽  
Wide Range ◽  
Immiscible Blend ◽  
Induced Crystallization

Polymer–polymer systems with special phase morphology were prepared, leading to an exceptional combination of strength, modulus, and ductility. Two immiscible polymers: poly(ε-caprolactone) (PCL) and polyhydroxyalkanoate (PHA) were used as components for manufacturing a nanoblend and a nanocomposite characterized by nanodroplet-matrix and nanofibril-matrix morphologies, respectively. Nanofibrils were formed by high shear of nanodroplets at sufficiently low temperature to stabilize their fibrillar shape by shear-induced crystallization. The effects of nanodroplet vs. nanofiber morphology on the tensile mechanical behavior of the nanocomposites were elucidated with the help of in situ 2D small-angle X-ray scattering, microcalorimetry and 2D wide-angle X-ray diffraction. For neat PCL and a PCL/PHA blend, the evolution of the structure under uniaxial tension was accompanied by extensive fragmentation of crystalline lamellae with the onset at strain e = 0.1. Limited lamellae fragmentation in the PCL/PHA composite occurred continuously over a wide range of deformations (e = 0.1–1.1) and facilitated plastic flow of the composite and was associated with the presence of a PHA nanofiber network that transferred local stress to the PCL lamellae, enforcing their local deformation. The PHA nanofibers acted as crystallization nuclei for PCL during their strain-induced melting–recrystallization.

scholarly journals In situ X-ray Diffraction Investigation of the Crystallisation of Perfluorinated Ce(IV)-based Metal-Organic Frameworks with UiO-66 and MIL-140 architectures

2020 ◽  
Author(s):  
Stephen Shearan ◽  
Jannick Jacobsen ◽  
Ferdinando Costantino ◽  
Roberto D’Amato ◽  
Dmitri Novikov ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Metal Organic Frameworks ◽  
Building Blocks ◽  
Nucleation And Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rate Determining Step ◽  
Wide Range ◽  
Metal Organic

We report on the results of a thorough <i>in situ</i> synchrotron powder X-ray diffraction study of the crystallisation in aqueous medium of two recently discovered perfluorinated Ce(IV)-based metal-organic frameworks (MOFs), analogues of the already well investigated Zr(IV)-based UiO-66 and MIL-140A, namely, F4_UiO-66(Ce) and F4_MIL-140A(Ce). The two MOFs were originally obtained in pure form in similar conditions, using ammonium cerium nitrate and tetrafluoroterephthalic acid as building blocks, and small variations of the reaction parameters were found to yield mixed phases. Here, we investigate the crystallisation of these compounds <i>in situ</i> in a wide range of conditions, varying parameters such as temperature, amount of the protonation modulator nitric acid (HNO<sub>3</sub>) and amount of the coordination modulator acetic acid (AcOH). When only HNO<sub>3</sub> is present in the reaction environment, F4_MIL-140A(Ce) is obtained as a pure phase. Heating preferentially accelerates nucleation, which becomes rate determining below 57 °C, whereas the modulator influences nucleation and crystal growth to a similar extent. Upon addition of AcOH to the system, alongside HNO<sub>3</sub>, mixed-phased products, consisting of F4_MIL-140A(Ce) and F4_UiO-66(Ce), are obtained. In these conditions, F4_UiO-66(Ce) is always formed faster and no interconversion between the two phases occurs. In the case of F4_UiO-66(Ce), crystal growth is always the rate determining step. An increase in the amount of HNO<sub>3</sub> slows down both nucleation and growth rates for F4_MIL-140A(Ce), whereas nucleation is mainly affected for F4_UiO-66(Ce). In addition, a higher amount HNO<sub>3</sub> favours the formation of F4_MIL-140A(Ce). Similarly, increasing the amount of AcOH leads to slowing down of the nucleation and growth rate, but favours the formation of F4_UiO-66(Ce). The pure F4_UiO-66(Ce) phase could also be obtained when using larger amounts of AcOH in the presence of minimal HNO<sub>3</sub>. Based on these <i>in situ</i> results, a new optimised route to achieving a pure, high quality F4_MIL-140A(Ce) phase in mild conditions (60 °C, 1 h) is also identified.

In situ characterization of strain-induced crystallization of natural rubber by synchrotron radiation wide-angle X-ray diffraction: construction of a crystal network at low temperatures

Soft Matter ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 734-743 ◽  
Author(s):  
Pinzhang Chen ◽  
Jingyun Zhao ◽  
Yuanfei Lin ◽  
Jiarui Chang ◽  
Lingpu Meng ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Structural Evolution ◽  
X Ray Diffraction ◽  
In Situ Characterization ◽  
X Ray ◽  
Crystal Network ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

The structural evolution of NR during stretching at −40 °C and in the strain–temperature space.

In Situ High Temperature X-Ray Diffraction Studies of Modified Poly(Ethylene Terephthalate)

1992 ◽  
Vol 36 ◽  
pp. 379-386
Author(s):  
T. Blanton ◽  
R. Seyler
Keyword(s):  
High Temperature ◽  
Ethylene Terephthalate ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Pet Crystallization

The effect of dimethyl-5-sodiosulfoisophthalate, SIP, on poly(ethylene terephthalate), PET, crystallization has been studied using in situ high-temperature x-ray diffraction, HTXRD. At low levels of SIP modification, PET-like crystallinity was observed. At high SIP levels, clustering of polyester ionomers was observed and crystallization was significantly suppressed. The HTXRD data along with differential scanning calorimetry, DSC, and small angle x-ray scattering, SAXS, indicate that the change from bulk crystallization to bulk ionomer formation occurred when 8-12 mol% of the diester linkages contained SIP.

Probing the Nature of Strain-Induced Crystallization in Polyisoprene Rubber by Combined Thermomechanical and In Situ X-ray Diffraction Techniques

2005 ◽  
Vol 38 (16) ◽  
pp. 7064-7073 ◽  
Author(s):  
Shigeyuki Toki ◽  
Igors Sics ◽  
Benjamin S. Hsiao ◽  
Masatoshi Tosaka ◽  
Sirilux Poompradub ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Extensional rheometer for in situ x-ray scattering study on flow-induced crystallization of polymer

2011 ◽  
Vol 82 (4) ◽  
pp. 045104 ◽  
Author(s):  
Yanping Liu ◽  
Weiqing Zhou ◽  
Kunpeng Cui ◽  
Nan Tian ◽  
Xiao Wang ◽  
...  
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Induced Crystallization ◽  
Flow Induced Crystallization ◽  
Ray Scattering

In Situ Synchrotron SAXS/WAXD Study during Uniaxial Drawing of Poly (L-Lactic Acid)

2014 ◽  
Vol 1048 ◽  
pp. 404-409
Author(s):  
Takahiko Kawai ◽  
Shin-ichi Kuroda
Keyword(s):  
Lactic Acid ◽  
Mechanical Response ◽  
Early Stage ◽  
Amorphous Film ◽  
X Ray Diffraction ◽  
X Ray ◽  
Saxs Measurement ◽  
X Ray Scattering ◽  
Shish Structure

The structure development of poly (L-lactic acid)(PLLA) during the uniaxial drawing was investigated by means of in-situ simultaneous wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) measurements. When the quenched amorphous film of PLLA was drawn at 77.2 oC, which was well above the glass transition temperature of PLLA, two different crystal structures were formed depending on the strain. The mesophase, which has 103 helix with large amount of packing disorder, was formed at the early stage of drawing, followed by the crystal transformation into α’ form (ε ≥ 1.5). SAXS measurement showed that the kebab formation begins at the stage later than that of meso-α’ transition. It strongly suggests that the transition takes place inside the shish structure. The development of kebab leads to the enhancement of mechanical response, which is found to be the origin of the strain hardening of PLLA.

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