X-ray diffraction method
Md Sohanur Rahman Sobuj
Latest posts by Md Sohanur Rahman Sobuj (see all)
- Thermal Properties of Polymers - April 26, 2019
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X-ray diffraction method
It is an independent method to determine the amount of crystalline matter present in the fiber. W. L. Bragg presented a simple explanation of the diffracted beams from a crystal.
When X-ray beam is incident on a crystal, it strongly reflected wherever its layers of atoms at an angle show in fig. Such that, nλ=2dsinθ
Where
n=1, 2, 3 . . . (order of diffraction)
λ= wave length of X‑rays.
d=distance between two atomic layers of crystal
θ=angle of incident radiation
From the figure we get,
∠BEC= ∠B’ EC=90⁰
∴∠DEC= ∠FEC= (90⁰- θ)
Here,
∠CDE=90⁰
In ∆CDE, ∠CDE+∠DEC+∠DCE =180⁰
⇒90⁰+90⁰- θ+∠DCE=180⁰
∴∠DCE= θ
sin θ= DE/CE=DE/d
∴DE=d sin θ
Again,
∠EFC=90⁰
In ∆EFC, ∠EFC+∠CEF+∠ECF =180⁰
⇒90⁰+90⁰- θ+∠ECF=180⁰
∴∠ECF= θ
sin θ=EF/CE =EF/d
∴EF= sin θ
So, the path difference between the two rays=DE+EF
= d sin θ +d sin θ
= 2d sin θ
Thus, for constructive interference,
2d sin θ=nλ
This equation is known as Bragg’s equation.
Advantages of X-ray diffraction method
⦿ It gives information about only crystallinity of a fiber.
⦿ It gives information about internal structure of the fiber.
⦿ It gives information about the shape of scattering particles.
⦿ It gives information about the distribution of spacing between the particles.
X-ray diffraction (XRD) spectrum of crystalline, semi-crystalline and amorphous polymer
Difference between IR method and X-ray method of fiber investigation
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Md Sohanur Rahman Sobuj
Latest posts by Md Sohanur Rahman Sobuj (see all)
- Thermal Properties of Polymers - April 26, 2019
- Frictional Properties - September 15, 2018
- Torsional Properties of Textile Materials - August 30, 2018
