Fibre testing for other fibres properties
 |
| Fibre properties |
Fibre friction
- Fibre friction is an important factor because it contributes to yarn strength.
- The total sliding distance is corresponding to the maximum fibre length in the sample.
- The resulting relationship between frictional force and sliding distance is termed the "friction profile" of fibres, and it can be used to determine the frictional force corresponding to a certain fibre intensity.
- Fibre friction value and its information are used to clear prediction of
- spinning value of cotton, so that yarn properties can be estimated.
- The friction of Fiber is lesser in the case of low-twist yarn, in which breakage often occurs as a result of fibre slippage rather than fibre fracture.
Measurement of fibre friction
Fibre friction is measured by three main methods.
In the first method, a 3/8 inch length of a group of 10 cotton fibres is taken and then pulled between two pads made of parallelized fibres of the same cotton and subjected to a known pressure.
The force required to pull out the group of 10 fibres is measured by a mechanism similar to the one employed on the 0’ Neill single fibre strength tester.
This force shows the friction value of fibres in the bunch. (This method is basically a modification of Adderley’s method.)
In the second method, the frictional force is measured by its slippage capacity.
Friction is measured at two angles of slippage (0o and 30o) from a calibrated apparatus designed for measured friction.
This is a simple but less efficient method.
In the third method, friction is measured by the technique of the application of pressure between fibre pads.
In this method, the fibre pad is simplified and then the force required to withdraw 20 parallel fibres is measured.
Torsional Rigidity of fibres
- The torsional rigidity of fibres is the resistance of fibres toward twisting.
- The torsional rigidity of fibre is defined as the torque required to twist a one-centimetre length of yarn to twist 360o.
- Torsional rigidity is more important in spinning because the difficulty of binding rigid fibres together could result in the production of bulky yarns.
- The torsional rigidity is proportional to the product of the rigidity modulus and the square of the area of the cross-section of the fibre, the constant of proportionality being dependent on the cross-sectional shape.
Measurement of torsional rigidity
The torsional rigidity is measured on a bundle of fibres weighing about 1 mg.
The single fibre torsional rigidity is achieved from the bundle fibre rigidity value. Single-fibre rigidity is achieved by dividing bundle rigidity by the number of fibres used for bunch testing.
Although the values obtained by this method are not identical to those obtained by measurement on single fibres, there is a high correlation between the two and hence the bundle method can be adopted to save time.
Lustre of fibres
- Lustre and the colour of cotton are two main characteristics that affect the aesthetic sense of the observer.
- Lustre represents the ability of the fibre to reflect light preferentially in some directions. (While colour indicates the hue and the strength of the hue.)
- White cotton has a lower value of lustre, A creamy and yellowish cotton has a higher value of lustre.
- Lustre is measured using a lustre meter fabricated for this purpose.
- In the lustre meter instrument, the sample is illuminated at an angle of 45o by a collagist reflected from the sample received by a photocell and the intensity is obtained in terms of photo-current measured on an ammeter.
- The intensity of specular reflection (45o) and the intensity of diffuse reflection in the direction normal to the sample is noted.
- The ratio of the two intensities known as the contrast ratio is used to express the lustre of the sample.
- (This instrument can be also used for tests on fibre, yarn, or fabric.)
Naps in fibres
- Naps of fibre have a higher impact on yarn quality and the spinning process.
- Naps are mainly generated in the presence of thin-walled immature fibres.
- Apart from maturity, small bits or fragments of seed particles attached to the fibre also form neps.
- Neps are also formed during the processing of the ginning. When rubbing of surfaces takes place, as in carding, minute knots of tangled fibres are caused and the immature fibres are more prone to this napping effect.
- When fine cotton is being processed, the danger of napping is even more acute, since even the mature fibres are likely to cause neps by faulty processing.
- In addition, the neps so formed are usually more prominent because of their size relative to the diameter of the fine yarn.
Questions -
- What is fibre friction?
- Why fibre friction is measured?
- How to measure fibre friction?
- What is the torsional rigidity of fibre?
- Why torsional rigidity of fibre is measured?
- How to measure torsional rigidity?
- What is the lustre of fibre?
- Why lustre of fibres is measured?
- What are naps in fibres?
References
Cenote, M. (2015). Google Books. In The SAGE Guide to Key Issues in Mass Media Ethics and Law (pp. 847–858). SAGE Publications, Inc.
Fundamental textile testing: Mechanical and Physical Tests. (n.d.). Fundamental Textile Testing: Mechanical and Physical Tests. from https://www.eurofins.com/textile-leather/articles/fundamental-textile-testing-mechanical-and-physical-tests/
Handbook of textile testing and quality control - Google search. (n.d.). G.Co. from https://g.co/kgs/RvVMgm
NPTEL IIT. (n.d.). Note.Ac.In. from https://nptel.ac.in/courses/116102029
Elsevier. (2016). Performance testing of textiles (1st ed.). Woodhead Publishing.
Houck, M. M. (2009). Identification of Textile Fibers (M. M. Houck, Ed.; 1st ed.). Woodhead Publishing.
Textile School. (2010, October 27). Fibre Identification - tests to identify a fibre. Textile School. https://www.textileschool.com/321/fiber-identification-tests-to-identify-a-fibre/
Trivedi, Y. (2020, April 10). Identification of Textile Fibers. Textilesphere.com. https://www.textilesphere.com/2020/04/identification-of-textile-fibers.html
(N.d.). Textilelearner.net. from https://textilelearner.net/classification
Writer - DSPAT Team
