1. Relationships between fiber and yarn tensile properties
E. Hequet1,2, N. Abidi1, J. Gannaway2
1Texas Tech University – PSS-ITC
2Texas A&M - TAES
Funded by International Cotton Research Center and the Texas Department of Agriculture - FFR
January 10, 2008

2. Background
Cotton breeding programs must strive to deliver fibers that perform better in textile manufacturing.
This is critical for effective competition with various man-made fibers and with international growths of cotton.

3. Background
Several fiber properties not measured in the cotton breeding programs have a large impact on processing performance.
Among these are the elongation characteristics associated with fiber strength.

4. Background
In general, most of the breeders simply ignore fiber elongation because:
The weak negative correlation between HVI elongation and HVI strength.
The lack of calibration procedures for HVI elongation makes it impossible to rely on such data.

5. Elongation vs. HVI tenacity 547 wild-type cotton samples
R2 = ***

6. Elongation vs. HVI tenacity 567 commercial varieties

7. Background
There is a weak negative correlation between fiber elongation and tenacity. However, this level of correlation does not preclude simultaneous improvement of fiber tenacity and fiber elongation.

8. Work of rupture calculations
We cannot record the curves load-elongation for the HVI. Nevertheless, the HVI work of rupture should be related to the product tenacity * elongation.

9. Protocol: Experiment 2
To confirm this we tested 32 samples on a tensile tester (50 reps per bale – speed of the pulling clamp 50 mm/min).
Recorded the force-elongation curves.
Calculated the work of rupture.

10. Tensile Strength Tester

11. Load vs. Elongation l0

12. Work of rupture from testometric vs. HVI Tenacity * Elongation

13. Estimated HVI work of rupture WSS vs
Estimated HVI work of rupture WSS vs. HVI Tenacity for selected elongations 9%
Base: 24 cN/tex – 6% El. 8% 7% 6% 5% 4%

14. Background
This demonstrates the importance of fiber elongation in the work of rupture of fiber bundles.
Breeding for improved work of rupture should result in lower fiber breakage when the cotton fibers are submitted to different mechanical stresses (ginning, carding, spinning, and weaving).

15. Experiment 1
Repeatability of HVI tensile properties

16. Repeatability of HVI tensile properties
3 bales homogenized according to ICCS protocol
Card web samples tested 6 times per day during a three days period
10 replications

17. Repeatability of HVI tensile properties

18. Repeatability of HVI tensile properties

19. Repeatability of HVI tensile properties

20. Repeatability of HVI tensile properties

21. Repeatability of HVI tensile properties
The current HVI systems do not provide elongation measurements as repeatable as we would like.
Nevertheless, the repeatability is good enough to distinguish between high, medium, and low elongation.
It should suffice for breeding programs.

22. Experiment 2
Fiber properties vs. yarn tensile properties

23. Fiber properties vs. yarn tensile properties
21 cultivars were selected.
Planted with two field replicates at TAES.
Stripper harvested and saw ginned (seed cotton cleaners + lint cleaning).
Lint tested on HVI (4-4-10) and AFIS (5 reps of 3,000 fibers).
30Ne carded ring spun yarn (Suessen Fiomax 1000).
Yarn tested on UT3 and Tensorapid.

24. HVI Strength among cultivars and field replications
R2 (Rep 1 vs. Rep 2) = 0.780

25. HVI elongation among cultivars and field replications
R2 (Rep 1 vs. Rep 2) = 0.914

26. Fiber properties vs. yarn tensile properties
The charts of the HVI tensile properties among cultivars and field replications show that there is little variations between replications (environment) and large variations between cultivars (genetic).

27. Yarn tenacity among cultivars and field replications
R2 (Rep 1 vs. Rep 2) = 0.914

28. Yarn tenacity among cultivars and field replications
R2 (Rep 1 vs. Rep 2) = 0.700

29. Fiber properties vs. yarn tensile properties
The charts of the yarn tensile properties among cultivars and field replications show that there is little variations between replications (environment) and large variations between cultivars (genetic).
This confirms that these two fiber and yarn parameters are quite heritable.

30. Yarn work of rupture (RS 30Ne) vs. Tenacity * Elongation

31. Fiber properties vs. yarn tensile properties
There is a direct effect of both yarn elongation and yarn tenacity on the yarn work of rupture
Therefore, to improve yarn performance the breeders should work on both yarn elongation and yarn tenacity.

32. Fiber properties vs. yarn tensile properties
Due to the cost of spinning tests and the amount of raw material needed to perform such tests, yarn tensile properties need to be predicted from fiber properties.

33. Yarn elongation: Predicted vs. Observed (RS 30Ne)

34. Yarn strength: Predicted vs. Observed (RS 30Ne)
Predicted = L(w) – Hs MR
R2 = 0.938

35. Fiber properties vs. yarn tensile properties
Breeding for fiber strength and elongation only will not always lead to better yarns. The cotton fibers need also to be more mature and finer, as well as longer and more uniform.
It is of interest to note that yarn strength can be better predicted with AFIS than with HVI.

36. Experiment 3
Validation: Fiber properties vs. yarn tensile properties

37. Validation fiber properties vs. yarn tensile properties
32 commercial bales were selected.
Lint tested on HVI (4-4-10) and AFIS (5 reps of 3,000 fibers).
30Ne carded ring spun yarn (Suessen Fiomax 1000).
Yarn tested on UT3 and Tensorapid.

38. Validation fiber properties vs. yarn tensile properties
On this independent set of cottons the same relationships were found. The best single predictor of yarn elongation is fiber elongation with a coefficient of correlation of while the best single predictor of yarn strength is standard fineness with a coefficient of correlation of

39. Experiment 4
Validation over a large range of yarn counts

40. Validation fiber properties vs. yarn tensile properties
4 commercial bales were selected.
Lint tested on HVI (4-4-10) and AFIS (5 reps of 3,000 fibers).
Combed ring spun yarn from 32Ne to 78Ne (Suessen Fiomax 1000).
Yarn tested on UT3 and Tensorapid.

41. Evolution of yarn tenacity over a range of yarn counts

42. Evolution of yarn elongation over a range of yarn counts

43. Validation over a large range of yarn counts
There are no interactions between the yarn tenacity or the yarn elongation readings and the yarn counts.
The intercepts are different but not the slopes.
Therefore, we can expect similar rankings of the cultivars for any yarn count (within the spinable range for that cultivar)..

44. Conclusion
The work of rupture (of a bundle of fibers or a yarn) is critically important and is determined by both tenacity and elongation.
We demonstrated that a combination of fiber properties could provide good estimates of yarn elongation and yarn strength.

45. Conclusion
Even though the HVI elongation measurement needs to be perfected, its use in breeding programs could lead to improved yarn quality and processing performance.