Nanocomposites of PCL and SBA-15 Particles Prepared by Extrusion: Structural Characteristics, Confinement of PCL Chains within SBA-15 Nanometric Channels and Mechanical Behavior

A study of different nanocomposites based on poly(ε-caprolactone) (PCL) and mesoporous SBA-15 silica that were prepared by melt extrusion was carried out by analyzing the possible effect of this filler on the crystalline details of PCL, on its mechanical behavior, and on the eventual observation of the confinement of the polymeric chains within the hollow nanometric silica channels. Thus, simultaneous Small-Angle and Wide-Angle X-ray Scattering (SAXS/WAXS) synchrotron experiments at variable temperature were performed on these PCL nanocomposites with different mesoporous silica contents. The importance of the morphological and structural features was assessed by the changes that were observed during the mechanical response of the final materials, which determined that the presence of mesoporous particles leads to a noticeable reinforcing effect.

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Synchrotron and Raman Study of the Rotator Phases and Polymorphism in Tricosane Paraffin

Polymers ◽

10.3390/polym12061341 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1341

Author(s):

Enrique Blázquez-Blázquez ◽

Rosa Barranco-García ◽

María L. Cerrada ◽

Juan C. Martínez ◽

Ernesto Pérez

Keyword(s):

Phase Behavior ◽

Variable Temperature ◽

Low Frequency ◽

Frequency Region ◽

Time Variable ◽

Wide Angle ◽

Multistage Model ◽

X Ray ◽

X Ray Scattering ◽

Raman Study

A detailed study of the phase behavior of n-paraffin C23H48 has been performed by means of real-time variable-temperature experiments with synchrotron radiation. Two detectors were employed for simultaneous analysis of the small-angle (SAXS) and wide-angle X-ray-scattering (WAXS) regions. This paraffin presents a very interesting phase behavior, involving two crystal polymorphs, three rotator phases and the liquid state. The Ostwald rule of stages is invoked to find similarities of the rotator phases with the eventual transient mesomorphic structure in the multistage model of polymer crystallization. That study is complemented by variable-temperature Raman experiments covering frequencies down to 150 cm−1. It was found that the low-frequency region is the most informative regarding the phase transitions, and specifically the intensity of the first overtone. From these analyses, several parameters are evaluated as function of temperature.

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Nuclear magnetic resonance and wide angle X-ray scattering in poly(acrylonitrile-co-methyl acrylate): 1. The influence of comonomer on structural characteristics and annealing behaviour

Polymer ◽

10.1016/0032-3861(89)90035-9 ◽

1989 ◽

Vol 30 (7) ◽

pp. 1187-1196 ◽

Cited By ~ 9

Author(s):

J GROBELNY ◽

M SOKOL ◽

E TURSKA

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Methyl Acrylate ◽

Structural Characteristics ◽

Wide Angle ◽

X Ray ◽

Annealing Behaviour ◽

X Ray Scattering ◽

Poly Acrylonitrile ◽

Nuclear Magnetic

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Confinement in Extruded Nanocomposites Based on PCL and Mesoporous Silicas: Effect of Pore Sizes and Their Influence in Ultimate Mechanical Response

Journal of Composites Science ◽

10.3390/jcs5120321 ◽

2021 ◽

Vol 5 (12) ◽

pp. 321

Author(s):

Tamara M. Díez-Rodríguez ◽

Enrique Blázquez-Blázquez ◽

Nadine L. C. Antunes ◽

Maria do Rosário Ribeiro ◽

Ernesto Pérez ◽

...

Keyword(s):

Mechanical Response ◽

Variable Temperature ◽

Morphological Characteristics ◽

Structural Features ◽

Mesoporous Silicas ◽

Accurate Information ◽

Pore Sizes ◽

X Ray Scattering ◽

Lower Temperature ◽

Mcm 41

In this study, nanocomposites based on polycaprolactone (PCL) and two types of mesoporous silicas, MCM-41 and SBA-15, were attained by melt extrusion. The effect of the silica incorporated within the PCL matrix was observed, firstly, in the morphological characteristics and degradation behavior of the resultant composites. DSC experiments provided information on the existence of confinement in the PCL–SBA-15 materials through the appearance of an additional small endotherm, located at about 25–50 °C, and attributed to the melting of constrained crystallites. Displacement to a slightly lower temperature of this endothermic event was observed in the first heating run of PCL–MCM-41 composites, attributed to the inferior pore size in the MCM-41 particles. Thus, this indicates variations in the inclusion of PCL chains within these two mesostructures with different pore sizes. Real-time variable-temperature small-angle X-ray scattering (SAXS) experiments with synchrotron radiation were crucial to confirm the presence of PCL within MCM-41 and SBA-15 pores. Accurate information was also deduced from these measurements regarding the influence of these two mesoporous MCM-41 and SBA-15 silicas on PCL long spacing. The differences found in these morphological and structural features were responsible for the ultimate mechanical response exhibited by the two sets of PCL nanocomposites, with a considerably higher increase of mechanical parameters in the SBA-15 family.

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A Revised O2 Reduction Model in Li-O2 Batteries as Revealed by in Situ Small Angle X-Ray Scattering

10.26434/chemrxiv.11447775.v1 ◽

2019 ◽

Author(s):

Christian Prehal ◽

Aleksej Samojlov ◽

Manfred Nachtnebel ◽

Manfred Kriechbaum ◽

Heinz Amenitsch ◽

...

Keyword(s):

Small Angle ◽

Wide Angle ◽

Reduction Mechanism ◽

Reduction Model ◽

X Ray ◽

X Ray Scattering ◽

O2 Reduction ◽

Ray Scattering

<b>Here we use in situ small and wide angle X-ray scattering to elucidate unexpected mechanistic insights of the O2 reduction mechanism in Li-O2 batteries.<br></b>

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