Elastomeric Yarn Testing
with Lawson Hemphill E-CTT

INTRODUCTION

Today, the textile industry mostly relies on the static test methods to measure the elongation level of the elastomeric yarns. These methods, do not always predict the performance of the yarns during covering, knitting or weaving due to nature of the tests.

Lawson Hemphill developed an elastomeric yarn test instrument called the CCT-E

This machine uses dynamic measurement principle to provide better and more accurate prediction of the elastomeric yarn draftability, elongation and friction properties.

There are 3 tests taht we run on the E-CTT to measure Elastomeric Yarn properties:

Draw Ratio Test

Elongation Test

Pin-Friction Test

Draw Ratio Test

This test is done to measure the DRAFTABILITY and the COMFORT level of the yarns. The software measures the TENSION on the yarn at 20 different Elongation levels and reports the highest Elongation % level that the yarn can be run without breaking.

Table 1 is the summary of DRAW RATIO tests that were run for eight different elastomeric yarn packages. The yarns were stretched from 50% up to 400% while the test speed was 100 m/min.

The results show that are DRAFTABILITY differences among the packages, which may be caused by the yarn production method. In addition, if you compare the tension at 200% Elongation, you can see that the tension on the 44 dtex wet samples is less than the tension on the 44 dtex dry samples. This information indicates that the fabrics that are produced by using the wet-spun yarns will be more COMFORTABLE to wear.

Table 1: Tension at Different Elongation % Levels

Speed	Yarn ID
100 m/min		50%	100%	150%	200%	250%	300%	350%	400%
44 dtex dry full	bobbin 1	3.03	5.82	10.00	17.61	30.19
44 dtex dry full	bobbin 2	2.81	5.18	8.66	14.59	25.40	45.31
44 dtex dry half	bobbin 3	2.71	5.28	8.66	25.22
44 dtex dry half	bobbin 4	3.08	5.90	10.11	17.86
44 dtex wet full	bobbin 5	4.18	6.77	8.98	11.16	13.36	15.96	19.78
44 dtex wet full	bobbin 6	3.69	5.94	8.07	10.49	14.19	20.10
22 dtex dry full	bobbin 7	2.40	4.55	9.05	19.13
22 dtex dry full	bobbin 8	2.42	4.66	9.41	19.16

Elongation Test

This test measures the Elongation % level of the yarn while it is running under constant tension. Table 2 compares the Elongation % of these eight packages when they run at 100m/min under 15g of constant tension.

TABLE 2: % ELONGATION at 15g of TENSION (Speed=100m/min)

Speed	Yarn ID
100 m/min		E%	Standard Deviation
44 dtex dry full	bobbin 1	203.01	3.89
44 dtex dry full	bobbin 2	218.96	3.08
44 dtex dry half	bobbin 3	220.45	2.40
44 dtex dry half	bobbin 4	176.03	2.56
44 dtex wet full	bobbin 5	294.38	3.87
44 dtex wet full	bobbin 6	283.98	5.76
22 dtex dry full	bobbin 7	189.30	2.50
22 dtex dry half	bobbin 8	194.22	1.85

Pin-Friction Test

This test is relevant to the spin finishes on the yarns. If the Coefficient of Friction increases, then the Tension on the yarn will also increase.

Table 3 compares the Coefficient of Friction values of these eight packages when they run at 100m/min

TABLE 3: Coefficient of Friction, m (Speed=100m/min)

Speed	100 m/min	44 dtex dry full	44 dtex dry full	44 dtex dry half	44 dtex dry half	44 dtex wet full	44 dtex wet full	22 dtex dry full	22 dtex dry half
Yarn ID		bobbin 1	bobbin 2	bobbin 3	bobbin 4	bobbin 5	bobbin 6	bobbin 7	bobbin 8
	m	0.33	0.33	0.34	0.33	0.33	0.36	0.39	0.37

Call Us Today

To learn how Lawson Hemphill or the TMI Group of Companies can help your company profit through testing, please call us at 1-508-679-5364, or e-mail Information@lawsonhemphill.com.

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Elastomeric Yarn Testing with Lawson Hemphill E-CTT

INTRODUCTION

Draw Ratio Test

Table 1: Tension at Different Elongation % Levels

Speed

Yarn ID

Elongation Test

TABLE 2: % ELONGATION at 15g of TENSION (Speed=100m/min)

Pin-Friction Test

TABLE 3: Coefficient of Friction, m (Speed=100m/min)

Call Us Today

Elastomeric Yarn Testing
with Lawson Hemphill E-CTT