Journal On: “Influence of sheath structure on twist and diameter of dref-III polyester-wool

blended friction-spun yarn”By,

S K Sinha & R Chattopadhyay

Indian Jounal of Fibre & Textile Research

Vol. 31, June 2006, pp. 286-292

Presented By: Md. Niloy RahmanMSc. 4th Batch Dept: Y.M.EID:2015-2-1-010 Presentation Date:22April2016

Inluence of sheath structure on twist and diameter of dref-III polyester-wool blended friction-spun yarn.

Abastract: The sheath composition and

structure were changed by varying core content and selectively placing polyester and wool in different layers of sheath.

Twist and yarn diameter observation. Varing drum speed & delivery speed.

Fig: Dref spinning

Introduction: > Torque between friction drum and fibers. > Polyester in Core & Sheath(Wool/Polyester/both) > Core fibers false twist & Sheath wrap the core fibers. > Twist depends(Drum speed/Del speed). > Dref-III-sheath may lay different layers.

Materials & Method:>Rieter C 1 /3 card and RSB 851 draw frame >Polyester: Staple length 48mm & fineness 11

Micron sliver 3.45gm/m.

>Wool: 54 mm mean length and fineness 25 micron sliver 2.18 gm/m

Materials & Method: Cont….Drafting Unit 1: Polyester Fibers(Core)Drafting Unit 2: Wool+Polyester Fibers(Sheath)Sheath fibers and its relative position:I. Sheath containing polyester and wool in the

inner and outer layer respectively is designated as structure A.

II. Sheath containing polyester, wool and polyester in alternate layers is designated as structure B.

III. All wool sheath is designated as structure C.

Materials & Method: Cont….

Fig: direction of sheath fiber approach

Materials & Method: Cont….

Total 81 yarn samples of 33Tex were spunDifferent friction drum speeds:

3500,4000,4500 rpmDifferent delivery speeds:

120,150,180m/minDifferent core sheath ratio:

50:50,60:40,70:30

Materials & Method: Cont….

Table: Different Sheath layers(P - Polyester fiber and W - Wool fiber.

Materials & Method: Cont….

Fig. Pictorial representation of the cross-section of yarn structures [Dark and light bands represent wool and polyester fibres respectively.]

Measurement of yarn twist & dia

Twist (turns / m) = (N2 - N1 ) x 39.37N1=Req. twist to break yarn same direction.N2=Req. twist to break yarn opposite direction

To measure yarn diameter:Yarn wound loosely on a board and microscopic test. At least 100 readings were taken per sample

Results and Discussion: (TWIST)

For 50:50 core sheath ratio(Turns/m)AI

759 707 667 801  741 673 826 759

701

B I 470 432 395 49 1 441 409 507 463 430

CI 3 1 5 290 27 1 328 301 279 339 3 1 1 289

For 60:40 core sheath ratio(Turns/m)A2   745 690 653 797 730 669 8 1 1 74 1

690

B2 46 1 428 389 488   437 404 50 1 460 425

C2 27 1 243 222 289 255 23 1 30 1 268 243

For 70:30 core sheath ratio(Turns/m)A3 701 645 589 73 1 653 601 738 697 64 1

 B3 4 1 5 39 1 368 459 4 1 3 379 469 438 400

C3 23 1 2 1 1 1 8 1 241 222 1 98 249 229 209

Table:Yarn twist,’a’ Friction drum speed in rpm,’b’delivery speed meter/min

3500a 4000a 4500a . 120b 150b 180b 120b 150b 180b 120b 150b 180b

Results and Discussion:(TWIST)Cont....The twist in structure A is always maximum,

whereas in structure C it is minimum.589-826 turns/m for structure A, 368-507

turns/m for structure B and 181 to 339 turns/m for structure C.

This friction, in turn, depends upon (i) the coefficient of friction between the fibres in the outer layer of the yarn tail & the friction drum and (ii) the normal force acting on it as a result of pressure difference due to suction acting through the perforations of the friction drums.

Results and Discussion:(TWIST)Cont....

The relationship of pressure difference (∆p) and airflow (F) is

k is the factor of form; η, the viscosity of air; s, the mean specific surface of fibers; m, the total mass of fibers; y, the fiber density; L, the length of the section of the chamber in which fibers are packed; and A, the area of the section.

Influence of friction ratio:Friction ratio is defined as the ratio of surface speed of friction drum and delivery speed. in this research the different ratios ranging between 2.7

and 5.3.

Fig:Effect of friction ratio on yarn twist A higher friction ratio indicates a higher drum speed

relative to delivery and hence a higher twist is expected.

Results and Discussion:(Yarn Diameter)• It is observed that the yarn diameter changes

with the change in sheath composition and structure.

Table: Diameter of yarn

Results and Discussion:(Yarn Diameter)Cont…The diameter is minimum for structure A

and maximum for structure C.The diameter increases marginally with the

increase in delivery speed for all the core sheath ratios.

Wool fibres being stiffer (due to being coarser) more crimpy and resilient are difficult to wrap around the core tightly.

The effective wrapping consolidates the core, thereby showing lesser yarn diameter.

Conclusions:

Higher the delivery speed reduction of twist.

Higher the friction ratio higher the twist.Stiffer character of wool less wraping

tendency less twist and higher the diameter.

Thanks to allThanks to all

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long polymeric chains with a parallel orientation. Kevlar derives its strength from inter-molecular hydrogen bonds and aromatic stacking interactions between aromatic groups in neighbouring strands.

Several grades of Kevlar are available: [1] Kevlar K-29 – in industrial applications, such as cables, asbestos replacement, brake linings, and body/vehicle armour.[2] Kevlar K49 – high modulus used in cable and rope products. [3] Kevlar K100 – coloured version of Kevlar [4] Kevlar K119 – higher-elongation, flexible and more fatigue resistant. [5] Kevlar K129–higher tenacity for ballistic applications. [6] Kevlar AP – has 15% higher tensile strength than [1] Kevlar KM2 – enhanced ballistic resistance for armour applications. The ultraviolet component of sunlight degrades and decomposes Kevlar

Figure 4. Molecular structure of Kevlar Superb Properties of Superb Properties of Kevlar ●It is strong but relatively light. ●Unlike most plastics it does not melt: it's reasonably good at withstanding temperatures and decomposes only at ~450°C (850°F). ●Kevlar can be ignited but burning usually stops when the heat source is removed. ●Very low temperatures have no effect on Kevlar. There is no appreciable embrittlement or degradation down to -196°C (-320°F), which makes it excellent for Arctic conditions. ●Like other plastics, long exposure to ultraviolet light (in sunlight, for example) causes discoloration and some degradation of the fibres. Kevlar can resist attacks from many different chemicals, though long exposure to strong acids or bases will degrade it over time. ●Kevlar remains virtually unchanged after exposure to hot water for more than 200 days and its properties are virtually unaffected by moisture.

Figure 11. Fibre Optics by Kevlar Figure 12. Different use of ropes & cables in different fields

Uses & Applications Military Body Armor & Jackets Protection Vests Military Helmets Automotive Uses Kevlar as a Composite Mass Transportation Figure 7. Jacket by Kevlar in Military Uniform

Kevlar in Fiber Optics Ropes and Cables Consumer Applications Other Uses

Figure 9. Kevlar in Automobile Cars

Figure: Military Helmets Figure 10. Kevlar in Aircraft

Conclusions Kevlar mainly use for two

reasons, and both are about performance: It’s lightweight and easy to integrate. A thin blanket can serve as structural reinforcement or ballistic protection, everywhere from seismic shear walls to bank counters. Sprinkle the fibres into carbon composites to cut weight and boost strength.