X-ray scattering studies of thermally modified Scots pine (Pinus sylvestris L.)

Holzforschung ◽  
2005 ◽  
Vol 59 (4) ◽  
pp. 422-427 ◽  
Author(s):  
Seppo Andersson ◽  
Ritva Serimaa ◽  
Tiina Väänänen ◽  
Timo Paakkari ◽  
Saila Jämsä ◽  
...  
Keyword(s):  
Pinus Sylvestris ◽  
Scots Pine ◽  
Small Angle ◽  
Microfibril Angle ◽  
Thermal Modification ◽  
Crystalline Cellulose ◽  
Angle Distribution ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

AbstractWood is thermally modified by heating and steaming in order to change its properties, e.g., to improve the biological resistance and to increase the hardness of wood. The structure of thermally modified Scots pine (Pinus sylvestris) was studied using wide-angle, small-angle and ultra-small-angle X-ray scattering methods. Modification temperatures varied from 100 to 240°C. No marked changes in the microfibril angle distribution were observed. The mass fraction of crystalline cellulose in wood (the crystallinity of wood) and the size of cellulose crystallites increased above 150°C. After modification at 230°C for 4 h the thickness of the cellulose crystallites increased from 3.1 to 3.4 nm. Thermal modification had no effect on the orientation of the voids, but an increase in the porosity of the cell wall was observed. The distance between cellulose crystallites was approximately 4.7 nm in hydrated wood and a decrease in order between microfibrils was observed at 160–200°C.

A Study of the Nanostructure of the Cellulose of Acacia mangium Wood by X-Ray Diffraction and Small-Angle X-Ray Scattering

2011 ◽  
Vol 364 ◽  
pp. 480-484 ◽  
Author(s):  
Tabet A. Tamer ◽  
Fauziah Abdul Aziz ◽  
Radiman Shahidan
Keyword(s):  
Small Angle ◽  
Microfibril Angle ◽  
Acacia Mangium ◽  
Mean Value ◽  
Tree Age ◽  
Crystalline Cellulose ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

The purpose of this study was to develop practical and reliable small-angle x-ray scattering and x-ray diffraction methods to study the nanostructure of the wood cell wall and to use these methods to systematically study the nanostructure of Acacia mangium wood grown in Sabah, Malaysia. Methods to determine the microfibril angle (MFA) distribution, the crystallinity of wood, and the average size of cellulose crystallites were developed and these parameters were determined as a function of the tree age and the distance from pith towards the bark. The mean MFA in Acacia mangium increases rapidly as a function of the number of the year and after the 7th year-old it varies between 6° and 10°. The thickness of cellulose crystallites for Acacia mangium appears to be constant as a function of the tree age after 10-year-old. The obtained mean value is 3.20 nm. The size of the cellulose crystallites was also quite constant after 11 year-old. The maximum value of the width of the crystallites for Acacia mangium was 2.34 nm at the pith region, while the minimum value was 0.290 nm at the bark region. The mass fraction of crystalline cellulose in wood is the crystallinity of wood and the intrinsic crystallinity of cellulose. The crystallinity of wood increases from the 3nd year-old to the 10th year-old from the pith and is constant after the 10th year.

Relationship between performance and microvoids of aramid fibers revealed by two-dimensional small-angle X-ray scattering

2013 ◽  
Vol 46 (4) ◽  
pp. 1178-1186 ◽  
Author(s):  
Caizhen Zhu ◽  
Xiaofang Liu ◽  
Jing Guo ◽  
Ning Zhao ◽  
Changsheng Li ◽  
...  
Keyword(s):  
Small Angle ◽  
Aramid Fiber ◽  
Angle Distribution ◽  
Two Dimensional ◽  
Fiber Morphology ◽  
Aramid Fibers ◽  
X Ray ◽  
X Ray Scattering ◽  
Fitting Method ◽  
Ray Scattering

Although the crystal structure in aramid fibers and the relationship between the size and orientation of crystallites and the performance of a material have been explored in detail, the effect of microvoids in an aramid fiber on its performance is still not clear. However, it is known that the mechanical properties depend strongly on the fiber morphology. In the present research, two-dimensional small-angle X-ray scattering is applied to characterize the microvoids in aramid fibers. Pauw's two-dimensional full pattern fitting method and scattering model have been enhanced by introducing orientation parameters, such as zenith angle distribution and azimuthal angle distribution, and instrumental parameters like point spread function and beam profile function. A series of aramid fibers with different strengths were studied using the new two-dimensional full pattern fitting method to extract the microvoid parameters from the scattering patterns. The results show that the microvoids in the aramid fiber affect the fiber strength directly. The greater the number of spherical microvoids and the larger the ellipsoidal microvoids, the weaker the aramid fiber.

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

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>

In situ Time-Resolved Small-Angle X-ray Scattering Reveals the Formation Kinetics of Polyelectrolyte Complex Micelles

2019 ◽  
Author(s):  
Hao Wu ◽  
Jeffrey Ting ◽  
Siqi Meng ◽  
Matthew Tirrell
Keyword(s):  
Small Angle ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Polyelectrolyte Complex ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Kinetics Of ◽  
Ray Scattering

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.

Small angle X-ray scattering study of porosity variation in a styrene-divinylbenzene copolymer

1981 ◽  
Vol 46 (7) ◽  
pp. 1675-1681 ◽  
Author(s):  
Josef Baldrian ◽  
Božena N. Kolarz ◽  
Henrik Galina
Keyword(s):  
Small Angle ◽  
Structural Parameters ◽  
Two Phase ◽  
X Ray ◽  
Porosity Variation ◽  
Swelling Agent ◽  
X Ray Scattering ◽  
Styrene Divinylbenzene ◽  
Ray Scattering

Porosity variations induced by swelling agent exchange were studied in a styrene-divinylbenzene copolymer. Standard methods were used in the characterization of copolymer porosity in the dry state and the results were compared with related structural parameters derived from small angle X-ray scattering (SAXS) measurements as developed for the characterization of two-phase systems. The SAXS method was also used for porosity determination in swollen samples. The differences in the porosity of dry samples were found to be an effect of the drying process, while in the swollen state the sample swells and deswells isotropically.

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