scholarly journals Tube Expansion Deformation Enables In Situ Synchrotron X-ray Scattering Measurements during Extensional Flow-Induced Crystallization of Poly l-Lactide Near the Glass Transition

Polymers ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 288 ◽  
Author(s):  
Karthik Ramachandran ◽  
Riccardo Miscioscia ◽  
Giovanni Filippo ◽  
Giuseppe Pandolfi ◽  
Tiziana Di Luccio ◽  
...  
2011 ◽  
Vol 82 (4) ◽  
pp. 045104 ◽  
Author(s):  
Yanping Liu ◽  
Weiqing Zhou ◽  
Kunpeng Cui ◽  
Nan Tian ◽  
Xiao Wang ◽  
...  

2000 ◽  
Vol 33 (25) ◽  
pp. 9385-9394 ◽  
Author(s):  
Rajesh H. Somani ◽  
Benjamin S. Hsiao ◽  
Aurora Nogales ◽  
Srivatsan Srinivas ◽  
Andy H. Tsou ◽  
...  

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1764
Author(s):  
Lison Rocher ◽  
Andrew S. Ylitalo ◽  
Tiziana Di Luccio ◽  
Riccardo Miscioscia ◽  
Giovanni De Filippo ◽  
...  

In situ synchrotron X-ray scattering was used to reveal the transient microstructure of poly(L-lactide) (PLLA)/tungsten disulfide inorganic nanotubes (WS2NTs) nanocomposites. This microstructure is formed during the blow molding process (“tube expansion”) of an extruded polymer tube, an important step in the manufacturing of PLLA-based bioresorbable vascular scaffolds (BVS). A fundamental understanding of how such a microstructure develops during processing is relevant to two unmet needs in PLLA-based BVS: increasing strength to enable thinner devices and improving radiopacity to enable imaging during implantation. Here, we focus on how the flow generated during tube expansion affects the orientation of the WS2NTs and the formation of polymer crystals by comparing neat PLLA and nanocomposite tubes under different expansion conditions. Surprisingly, the WS2NTs remain oriented along the extrusion direction despite significant strain in the transverse direction while the PLLA crystals (c-axis) form along the circumferential direction of the tube. Although WS2NTs promote the nucleation of PLLA crystals in nanocomposite tubes, crystallization proceeds with largely the same orientation as in neat PLLA tubes. We suggest that the reason for the unusual independence of the orientations of the nanotubes and polymer crystals stems from the favorable interaction between PLLA and WS2NTs. This favorable interaction leads WS2NTs to disperse well in PLLA and strongly orient along the axis of the PLLA tube during extrusion. As a consequence, the nanotubes are aligned orthogonally to the circumferential stretching direction, which appears to decouple the orientations of PLLA crystals and WS2NTs.


2007 ◽  
Vol 40 (1) ◽  
pp. 196-198 ◽  
Author(s):  
Karena W. Chapman ◽  
Peter J. Chupas ◽  
Charles A. Kurtz ◽  
Darren R. Locke ◽  
John B. Parise ◽  
...  

The use of a polymeric Torlon (polyamide–imide) gasket material in a Paris–Edinburgh pressure cell forin situhigh-pressure X-ray scattering measurements is demonstrated. The relatively low bulk modulus of the gasket allows for fine control of the sample pressure over the range 0.01–0.42 GPa. The quality of the data obtained in this way is suitable for Bragg and pair distribution function analysis.


2007 ◽  
Vol 1034 ◽  
Author(s):  
John David Ferguson ◽  
Arthur R. Woll ◽  
Gokhan Arikan ◽  
Darren S. Dale ◽  
Aram Amassian ◽  
...  

AbstractHomoepitaxial SrTiO3 thin films were grown on SrTiO3 (001) using Pulsed Laser Deposition (PLD). The deposition process was monitored in-situ, via both x-ray reflectivity and surface diffuse x-ray scattering measurements in the G3 experimental station at the Cornell High Energy Synchrotron Source (CHESS). Using a CCD detector in 1D, or streak-camera, mode with approximately 0.3-second time resolution, data were collected during growths performed at two substrate temperatures: 695°C and 1000°C. While the specular reflectivity oscillations for the two growths are very similar, the diffuse scattering clearly shows a distinct change in the peak position. Using Atomic Force Microscopy (AFM), we illustrate how the peak position for the diffuse lobes of scattered intensity is directly related to the distribution of single unit cell high islands on the growing surface. Thus, the peak shift of the diffuse scattering indicates an order of magnitude change in the island density.


2002 ◽  
Vol 47 (19) ◽  
pp. 3075-3080 ◽  
Author(s):  
Toshihiro Kondo ◽  
Kazuhisa Tamura ◽  
Masamitu Takahasi ◽  
Jun-ichiro Mizuki ◽  
Kohei Uosaki

2021 ◽  
Vol 12 (7) ◽  
pp. 1969-1972
Author(s):  
Fumitoshi Kaneko ◽  
Chihiro Katagiri ◽  
Ken Nagashima ◽  
Gen Sazaki

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