Small-angle Scattering Study of Mohair Fibres
Tjatji Tjebane
Instrument Scientist
(SANS)
NECSA-Wits workshop, NVC, 2015/09/11
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Outline
• Aim• Introduction• Mohair fibre• SANS Technique• Experiments• Results and Discussions• SANS Applications• Summary
NECSA-Wits workshop, NVC, 2015/09/11
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Aim
• Study mohair fibres using SANS technique• Understanding SANS data analysis technique
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Introduction
• Amorphous• Hygroscopicity and changes in fibre structure• Textile treatment technology
NECSA-Wits workshop, NVC, 2015/09/11
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Introduction
• Using heavy water (D2O) for contrast enhancement
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Mohair fibre
Natural fibre obtained from Angora goat. Exceptional properties: durable, resilient, thermal insulation, flame and crease
resistant, e.t.c.
Macromolecule - composite fibre - i.e. a fibril-reinforced matrix material with both the fibrils and the matrix consisting of polypeptides, interconnected physically and chemically.
Morphology – nanocomposite - (the reinforcing microfibrils have a diameter of about 10 nm) of high complexity with clear hierarchy indicating an enormous degree of self-organisation
Protein structure - only the fibrils are regarded as keratins - they being embedded into a protein matrix
NECSA-Wits workshop, NVC, 2015/09/11
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Mohair fibres , cont…
• Wool contains >170 different proteins• Proteins composed of amino acids• Amino acids differ in R- side group
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Mohair fibres, cont…
NECSA-Wits workshop, NVC, 2015/09/11
• Amino acids are joined to form long polymer chains
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SANS Technique
Source E (meV) λ (Å) T (K)
Sub-thermal (cold) 0.1 - 10 ~ 30 - 3 ~ 1 – 70
NECSA-Wits workshop, NVC, 2015/09/11
|q|= (4π/λ)sin(ϴ)
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Experiments
37.8 µm diameter CCl4 cleaned 20% weight D2O (Heavy water) Different S-D positions (0.98 and 5.5 m)
NECSA-Wits workshop, NVC, 2015/09/11
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Results and Discussions
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Results and Discussions, cont…
NECSA-Wits workshop, NVC, 2015/09/11
𝑄𝑚𝑎𝑥=2𝜋𝜆 ( 𝑟 𝐷
𝐿 )= 1𝑆𝑚𝑖𝑛
𝐼 (𝑄)=∑𝑛=1
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( 𝐼 𝑛 (0 )∗𝑒− (𝑄𝑅𝑔𝑛 )2 /3 )+𝐼𝑏𝑔 Rg = describes the dimensions of a polymer chain
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Results and Discussions, cont…
NECSA-Wits workshop, NVC, 2015/09/11
Sample Ibg I1(0)/Rg1 (nm)
I2(0)/Rg2 (nm)
I3(0)/Rg3 (nm)
Dirty 8300±91 70282±265/9.02±0.95
12984±114/6.00.±0.63
9946.±99/2.61±0.49
Clean 6400±80 260000±447/10.00.±0.10
14000±300/6.00.±0.63
9000.±89/2.41±0.49
𝐼 (𝑄)=∑𝑛=1
3
( 𝐼 𝑛 (0 )∗𝑒− (𝑄𝑅𝑔𝑛 ) 2 /3 )+𝐼𝑏𝑔
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Results and Discussions, cont…
Sample Ibg I1(0)/Rg1 (nm)
I2(0)/Rg2 (nm)
I3(0)/Rg3 (nm)
Dry 7600 ± 87 39900±199/9.70±.98
8900.±94/5.98±.76
4050±89/5.30±.73
Wet (D2O) 7600±87 91000±301/10.10±.10
13000±114/7.00±.84
8950±95/2.98±.55
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SANS Applications
Soft Condensed Matter Micelle, micro-emulsion, Surfactant polymer systems multi-phase block copolymers
Bio-molecular Systems Macromolecular proteins, viruses, membranes, vesicles drug delivery systems Food science
Advanced Materials Micro-porous systems, flux lattices, magnetic domains, metal alloys, precipitation and phase
separation
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Summary
• SANS (Sub-thermal neutrons) is molecular bond friendly and non-destructive technique
• Contrast variation method can be used for protein-rich materials
• SANS is a potential tool for bulk disordered systems
• Understanding wool fibre props allows different non-damaging treatment
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Acknowledgements
• Necsa (C. B. Franklyn)• CapeWool SA• BNC (Gy Tȍrȍk)• NRF and IAEA
NECSA-Wits workshop, NVC, 2015/09/11
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THANK YOU
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THANK YOU
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THANK YOU
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Way forward
• Increase D2O content in the samples
• Improve analysis• Continue development of SANS at Necsa
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Introduction, Mohair (wool) fibre
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SANS @ NECSA, cont…
Parameter BNC Necsa
q-range (Å-1) 0.003 – 0.500 ≤ 0. 182