Small-angle Scattering Study of Mohair Fibres

Tjatji Tjebane

Instrument Scientist

(SANS)

tjatji.tjebane@necsa.co.za

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

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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

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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

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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)

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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

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( 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

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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