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CHAPTER 4

CHARACTERIZATION OF CHICKEN

FEATHER FIBRE (CFF)

4.1 INTRODUCTION

It is possible to find in Nature an almost unlimited source of high

performance materials which remain to be critically studied to establish them

as basis for innovative technologies and useful raw materials. This is the case

of keratin fibre from chicken feathers.

Chicken feather comprises more than 90% protein, the major part

being beta-keratin, a fibrous and insoluble structural protein broadly cross

linked by disulfide bonds (Feughelman 2002). The CFF possesses good

resilient property because of the presence of more void space in its cross

section. Using the unnoticeable, cheap and plentiful feathers as fibres will

save the cost, benefit the environment and also help the fibre industry

sustainable.

Recognizing feather “waste” as a potential source of usable fiber,

studies demonstrate and develop that usefulness by making commercial value

added products were taken up. A chicken has about 5% to 7% of its body

weight in feathers so chicken feathers are an important by-product of the

poultry industry. Presently, the chicken feather “waste” as a potential source

of fibres (both original and regenerated) is being gradually recognized.

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4.2 MATERIALS AND METHODS

The materials and methods adopted are as discussed in chapter 3.

4.3 RESULTS AND DISCUSSION

The CFF have been characterized for their physical, chemical and

structural properties. Since CFF is a protein fibre it is compared with wool

fibre. Differential Scanning Calorimetry, Thermal Gravimetric Analyses test

to observe the thermal behaviour and High Performance Thin Layer

Chromatographic test to identify the amino acid content of CFF.

4.3.1 Physical Characteristic of CFF

Feughelman (2002) characterized the main physical properties like

length, fineness, tenacity, elongation at break, modulus, moisture content,

moisture regain and density of wool fibre. Table 4.1 shows the comparison of

wool and CFF.The result obtained from the oil plate method to get length

showed CFF has comparable effective length. The fineness of CFF is lower

than wool fibre. The single fibre strength of CFF is approximately double the

strength of wool, but the elongation at break is very low. From this it can be

understood that CFF will break easily during mechanical processing.

The length to diameter ratio value of CFF indicates that the

diameter of this fibre will vary from the tip to the base. When analyzed

through microscope no crimp was found in the CFF. The moisture content of

CFF was approximately same as wool fibre but the moisture regain value is

less when compared to wool fibre. The observed moisture content value of 12

to 14% of CFF is relatively similar to Kar and Misra (2004) cited value of 12-

13% in its as-received state. Measurements of moisture content made on

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feather fibre after storage in a controlled temperature (23°C) and relative

humidity (50% RH) environment were found to be 16% (Jeffrey W. Kock

2006). Schmidt and Line (1996) suggest that for feather fibre, the helical state

of the keratin becomes more strongly bound as water is removed, giving a

higher stiffness.

The density of the CFF is similar to that of wool fibre. But the

observed CFF density (1.12 g/cc) value was deviated from Barone and

Schmidt’s (2005) cited value of 0.89 g/cc. The difference in results may be

related to composition differences between the CFF samples studied.

Table 4.1 Physical Properties of Wool fibre and CFF

S.No. Physical Properties Wool Fibre CFF 1 Length 25 to 110 mm 25 to 34 mm 2 Fineness 10 Microns 4.18 Microns3 Single Fibre Strength (Tenacity at Break) 12.06 g/tex 23.99 g/tex 4 Elongation at Break 25 – 30 % 1 – 6 % 5 Modulus 5 g/tex 3.96 g/tex 6 Moisture Content 11 – 12 % 10 - 11 % 7 Moisture Regain 14 – 17 % 12 - 12.35 % 8 Density 1.31 g/cc 1.12 g/cc

4.3.2 Chemical Characteristic of CFF

In Table 4.2 the chemical properties of CFF have been given. The

structure of keratin, the primary constituent of CFF, affects its chemical

durability. Schrooyen (1999) found keratin to be insoluble in polar solvents,

such as water, as well as in non-polar solvents. The CFF loses its weight when

treated with acids and completely dissolved when treated with 5% sodium

hydroxide. Weight loss and damage will be observed while treating with water.

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Table 4.2 Chemical Properties of Wool fibre and CFF

Chemical Properties Wool Fibre CFF

Action of acids Except sulphuric acid, resistant to all other acids

Damaged and weight loss absorbed

Action of alkalis Dissolved when boiled (in 5 % NaoH)

Completely dissolved (in 5 % NaoH)

Action of solvent Sensitive to oxidizing agents

Sensitive and weight loss is observed

Action of cold water

Absorbs water and Swells Absorbs water and damaged

Action of hot water Becomes Weaker Weaker and weight loss observed

4.3.3 Burning Characteristics of CFF

The burning behavior of the CFF was as shown in Table 4.3 and it

was similar to the burning characteristics of wool fibre.

Table 4.3 Burning Characteristics of CFF and Wool fibre

Description

Burning Behaviour

Odour Ash When approaching

Flame

When in the Flame

Away from the Flame

WoolMelts away from flame

Melts and Burns

Supports combustion with difficulty, melts ahead

Burning

Hair

Easily crushable, black fluffy

CFF Melts away from flame

Melts and Burns

Supports combustion with difficulty, melts ahead

Burning

Hair

Easily crushable, black fluffy

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4.3.4 Structural Characteristic of CFF

The longitudinal view of CFF and wool fibre taken from SEM is

showed in Figure 4.1 A and B respectively. In CFF micro-fibrils are twisted

forming a helix that is responsible for the fibre’s high mechanical strength.

(a) (b)

Figure 4.1 Longitudinal view of a) CFF and b) Wool fibre

It is clear from the picture that the barbs have branches called as

barbules, which can contribute to the resilience property of the feathers.

The cleave lines or striations along the fibres give rise to a certain surface

roughness, which can contribute to interfacial strength that in addition to the

high length to diameter ratio reached for the fibre can be useful for reinforcing

composites (one of the possible applications of this fibre). The wool fibre

showed rough surface with scales protruding out.

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(a) (b)

Figure 4.2 Cross sectional view of a) CFF and b) Wool Fibre

The honeycomb structure in the cross sectional view of the CFF

showed in Figure 4.2A confirms the possibility of more air pockets in the

feather which contributes to the high thermal resistance characteristic and the

presence of two different structures inside the bio-fibres: micro-fibrils and

proto-fibrils. The former has a more order and crystalline structure than the

matrix. The proto-fibrils are inside the micro-fibrils and are also surrounded

by the matrix. From the cross sectional view it is clear that the CFF posses lot

of void space in that air pockets will be available which makes the fibre to act

as thermal retaining material. The wool fibre showed in Figure 4.2B

confirmed that it is nearly round; medulla present in coarse fibres is

concentric and irregular in size.

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4.3.5 X-Ray Diffraction Pattern of CFF

(a) (b) Figure 4.3 Diffraction patterns of a) CFF and b) Wool Fibre

A diffraction pattern of a CFF and wool fibre is shown in Figure 4.3.

As seen from the Figure 4.3(a) the CFF have brilliant and sharp diffraction

patterns. The diffraction patterns of the CFF indicate that the crystals are more

oriented than wool fibre shown in Figure 4.3(b). The diffraction intensities of the

CFF and wool fibre were compared in Figure 4.4. The diffraction intensities

show both the fibres are of similar pattern to each other. The % crystallinity of

CFF and wool was found to be 22.4% and 23.5%. This fact is supported by

earlier research by Reddy and Yang (2007).

Figure 4.4 Diffraction intensities of CFF and wool fibre

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4.3.6 Differential Scanning Calorimetry (DSC) of CFF

DSC tests were performed on the bulk sample to determine the

appropriate Tm. DSC curves of the CFFs and their melting temperatures (Tm)

obtained was shown in Figure 4.5.

Figure 4.5 DSC curve of CFF

A large, low-temperature peak was observed at 108oC. This peak

shows the amount of bound water in the keratin structure. This peak is on

occasion referred as the ‘‘denaturation’’ temperature. DSC results indicate

that temperatures below 110oC may not allow for the progress of moisture

(Jeffery Kock 2006). Partial degradation of CFF may occur at 186oC to

190oC. A narrow peak was observed at 241oC and was the crystalline melting

peak that shows a tighter keratin structure to which water is more strongly

bonded. The degradation was observed as a color change from white to black.

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4.3.7 Thermo Gravimetric Analysis (TGA) of CFF

The thermo gravimetric analysis graph of CFF is shown in Figure 4.6. From the graph it can be interpreted that the loss of moisture from CFF occurs in the range of 24oC-135oC. The loss of moisture content is about 8.9% (0.2671 mg), which probably implies the moisture present in the fibre is around 8.9%.

Figure 4.6 TGA graph of CFF

The partial decomposition of fiber in addition to the loss in moisture content occurred in the range of 186oC and fully decomposed at 577oC with a weight loss of 70.39% (2.112 mg). The fibre completely decomposed to its elements at around 577oC (Gaseous state). The fibres withstand up to 335.83oCwhich was supported from peak.

4.3.8 Composition and Amino Acid Sequence of CFF

Chicken feathers are approximately 91% protein (keratin), 1% lipids, and 8% water. The amino acid sequence of a chicken feather is very similar to that of other feathers and also has a great deal in common with reptilian keratins from claws (www.ornithology.com). The sequence is largely composed of cystine, glutamine, proline, and serine, and contains almost no histidine, lysine, Tryptophan, Glutamic acid and Glycine.

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Figure 4.7 - 3D Display of all Tracks of amino acid present in CFF

The 3D display of G1, G2, G3, G4 and tracks A, B, C of amino

acid present in CFF is shown in Figure 4.7. From Figure 4.7 it is apparent and

confirms that the following amino acids are present in the CFF and also the

percentage of the same is given in Table 4.4.

Table 4.4 Amino acid content in CFF

Functional Groups Amino acid % ContentsPositively charged Arginine 4.30

Negatively charged Aspartic acid 6.00Glutamine 7.62

Hygroscopic Theronine 4.00Serine 16.0

Hydrophobic

Tyrosine 1.00Leucine 2.62Isoleucine 3.32Valine 1.61Cystine 18.85Alanine 3.44Phenylalanine 0.86Methionine 1.02

Special Proline 12.0Asparagine 4.00

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Feather keratins are composed of about 20 kinds of proteins, which differ only by a few amino acids. The distribution of amino acids is highly non-uniform, with the basic and acidic residues and the cystine residues concentrated in the N- and C-terminal regions. The central portion is rich in hydrophobic residues and has a crystalline -sheet conformation.

Serine (16%) is the most abundant amino acid and the -OH group in each serine residue helps chicken feathers to absorb moisture from the air. Feather fibre is, therefore, hygroscopic. CFFs and quill have a similar moisture content of, around 11%.

Feather keratin is a special protein. It has a high content of cystine (18.85%) in the amino acid sequence, and cystine has -SH groups and causes the sulfur–sulfur (disulfide) bonding. The high content cystine makes the keratin stable by forming network structure through joining adjacent polypeptides by disulfide cross-links.

The presence of amino acids in the CFF which is hydrophobic in nature contributes about 33%. Hence, the CFF posses both Hydrophobic and Hygroscopic character and approximately the ratio will be 65:35 percentages respectively. This result is at par with the results of Alberts (1994).The estimated value of total Fat content in CFF is 1.53%.

4.4 CONCLUSION

The structure and properties of CFF throws light that it can be used in textile as other natural protein fibres. From the properties it can be understood that to spin the 100% CFF fibre is difficult because of its stiffness. The availability of chicken feather in large quantity and its low cost may make this fibre to be used in several applications in technical textiles such as composites, filter materials etc. Because of the presence of honeycomb cross section it has low density and also gives insulating capabilities.