Flex Abrasion Resistance- Determination

Method for determination of Flex abrasion resistance:

1. Cut five test specimens each 200mm. long and of 32 or 38mm width depending upon wheter the number of yarns/dm of the specimen is below or above 200. Ravel the specimen to 25 mm in width by removing from each side approximately the same number of yarns. Do not take two specimens fro the weft test from the same warp ends or any two specimens fro the weft test from the same picks. Take weft specimens at wide intervals.

2 After positioning the bar by means of the yoke holder, place the specimen between the pressure (upper) plate and the reciprocating (lower) plate of the apparatus and locate centrally. with the specified folding bar or folding blade inserted, after being clamped and loaded by removal of yoke holder, distribute the tension exerted by the bar or blade uniformly over the width of the specimen and align the long dimension both above and below the bar parallel to the direction of the reciprocating motion. Position the specimen with the fold at the centre of the upper plate, and the reciprocating plate at the rear of its stroke when the specimen is clamped.

3. Load the pressure plate and the folding bar or blade as required by the material specifications. In the absence of the material specification, the bar load sufficient to produce rupture in excess of at least 100 cycles and preferably in 300 cycles should be used, in combination with the lowest head load (pressure) sufficient to prevent vibration of the upper plate at the start of the test.

The ratio of the bar to head loads shall be 4:1

4. Check the bar alignment after the first 25 cycles. If shifting of bar from its normal position is noticed, discard the specimen and make the proper adjustment.

5. Remove the pills of matted fibres debris interfering with proper contact between the specimen and the folding bar or folding blade during the test if they cause a marked vibration of the pressure plate or otherwise interfere with proper abrasion. The pill should be removed by careful clipping. Do not correct the vibration of the pressure plate due to pilling by applying additional load. Check the position of the specimen after additional cycles to ensure that the removal of the pills has not altered the bar alignment.

6. If the specimen slips in the clamps or tension and pressure upon the folded specimen do not remain constant during the test, or an anomalous wear pattern is obtained, discard such individual measurements and test an additional specimen.

7. Before every test the blade is rinsed with degreasing agent.

8. The end point is determined by abrading the specimen until rupture and number of cycles is recorded.

9. The report should include the following information:

a. Abradent used, bar or blade
b. Average number of cycles required to produce rupture the specimen

Total No of cycles Report to the nearest cycle
Below 200 10
200 to 299 25
1000 to 4999 50
5000 and above 100

c. Tension and pressure used.

Acrylic- Manufacturing Process and Properties

Polyacrilonitrile ( Acrylic)

vinyl Cyanide, more commonly known as acrylonitrile, can under go addition polymerisation to form polyacrylonitrile.

Raw Material

Acrilonitrile is the main main raw material for the manufacture of acrylic fibres. It is made by different methods. In one commercial method, hydrogen cyanide is treated with acetylene:

acetylene + Hydrogen cyanide --> Acrilonitrile

2nd Method

Ethylene--Air Oxidation--> Ethylene oxide + HCN--> Ethylene cyanahydrin--Dehydration at 300 deg C (catalyst)--> Acrylonitrile

In a continuous polymerisation process, 95% acrylonitrile and 6% methyl acrylate (400 parts) 0.25% aqueous solution of K2S2O8(600 parts), 0.50 % Na2S2O5 solution ( 600 Parts) and 2N sulphuric acid (2.5 Parts) are fed into the reaction vessel at 52 deg C under nitrogen atmosphere giving a slurry with 67% polymer. The slurry is continuously withdrawn, filtered and washed till it is free from salts and dried.

Acrilonitrile is dry spun. The material is dissolved in dimethyl formamide, the solution contains 10-20 polymers. It is heated and extruded into a heated spinning cell. A heated evaporating medium such as air, nitrogen or steam moves counter current to the travel of filaments and removes the solvent to take it to a recovery unit. The filaments are hot stretched at 100 to 250 C depending on the time of contact in the hot zone, to several times their original length.

Properties of Acrylic Fibres

1. Acrylic has a warm and dry hand like wool. Its density is 1.17 g/cc as compared to 1.32 g/cc of wool. It is about 30% bulkier than wool. It has about 20% greater insulating power than wool.

2. Acrylic has a moisture regain of 1.5-2% at 65% RH and 70 deg F.

3. It has a tenacity of 5 gpd in dry state and 4-8 gpd in wet state.

4. Breaking elongation is 15% ( both states)

5. It has a elastic recovery of 85% after 4% extension when the load is released immediately.

6. It has a good thermal stability. When exposed to temperatures above 175 deg C for prolonged periods some discolouration takes place.

7. Acrylic shrinks by about 1.5% when treated with boiling water for 30 min.

8. It has a good resistance to mineral acids. The resistance to weak alkalies is fairly good, while hot strong alkalies rapidly attack acrylic.

9. Moths, Mildew and insects do not attack Acrylic.

10. It has an outstanding stability towards commonly bleaching agents.

Uses

1. Knit Jersey, Sweater, blankets
2. Wrinkle resistant fabrics.
3. Pile and Fleece fabrics
4. Carpets and rugs.

Determination of Abrasion Resistance of Fabric

Determination of Abrasion Resistance of Fabrics

Plain Abrasion Resistance

Apparatus - Universal Wear Tester

Prior to test, the fabric should be Conditioned to moisture equilibrium from the dry side, in the standard atmosphere of 65+-2% relative humidity and 27+-2 deg C temperature. The test should be carried under standard atmospheric conditions.

Method for determination of plane Abrasion Resistance

1. Cut five circular test specimens of 112 mm in diameter, taking care to take specimens from areas containin the same wales or courses in knitted fabric or the same warp or weft yarn in woven fabric.

2. Set the instrument for inflated diaphram test.

3. Place the specimen over the rubber diaphram in smooth condition and clamp the specimen in place without disturbing it.

4. Place the abrasive paper on the abradent plate under sufficient tension to be held smooth and in such a position that the contact pin, reaching through a hole in the abradent is even with the surface of the abradent. In the absence of any specific material specification , zero emery polishing paper should be used as the abradent.

5. Set the air pressure under the diaphram and load on the abradent plate. In the absence of any specific material specifications, the air pressure should be 0.3kg/sq.cm (4 p.s.i.) and the load on the abradent should be 454 gm. Ensure that the air pressure control and contact between the inflated specimen and loaded abradent is in a state of equilibrium before abrasion is started. To ensure consistent inflation of the diaphragm, inflate to a higher air pressure ( 25 per cent) and then reduce the testing pressure.

6. If the unidirectional abrasion is desired, disengage the rotation mechanism of the specimen clamp and bring the specimen into the direction by turning and setting the clamp after the diaphragm has been inflated.

7. In the event that multi-directional abrasion is required, or if no specific indication as to the abrasion direction is given in the fabric specification, engage rotation mechanism of the specimen clamp.

8. Remove pills of matted fibres interfering with proper contact between specimen and abradent during the test if they cause a marked vibration of the abradent plate.

9. If the specimen slips in the clamp or the air pressure does not remain constant during the test or anomalous wear pattern is obtained, discard such individual measurements and test an additional specimen..

10. One of the following methods is selected for determination of end point as per test specifications:

a. Breakage of Thread: Abrade the specimen until all fibres in the centre of the abraded area are worn off so that the diaphragm and abradent head come into contact and the instrument automatically stops.

b. Removing a predetermined thickness of the material. Abrade the specimen using the electrical depth micrometer to determine the automatic end-point for removing a predetermined thickness of the material from the specimen.

11. Unless the continuous changing abrasion head is used, abradent paper is changed after every 300 cycles.

12. Report shall include the following information :

a. Type of abradent
b. Type of abrasion ( unidirectional or multi directional)
c. No. of cycles to reach the end point as determined by electrical contact.

Related Links

Testing Abrasion Resistance For Socks

Properties of Polyester

Tenacity (gpd)	High Tenacity	Normal Tenacity	Staple
Dry	6-7	4.5-5.5	3.5-4
Wet	6-7	4.5-5.5	3.5-4
Elongation (%)
Dry	12.5-7.5	25-15	40-25
Wet	12.5-7.5	25-15	40-25
Density	1.38	1.38	1.38

Moisture Regain

At 65% RH and 70 deg F--> 0.4%

Because of low moisture regain, it develops static charge. Garments of polyester fibres get soiled easily during wear.

Thermal Properties

Polyester fibres are most thermally stable of all synthetic fibres. As with all thermoplastic fibres, its tenacity decreases and elongation increases with rise in temperature. When ignited, polyester fibre burns with difficulty.

Shrinkage

Polyester shrinks approx 7% when immersed in an unrestrained state in boiling water. Like other textile fibres, polyester fibres undergo degradation when exposed to sunlight.

Its biological resistance is good as it is not a nutrient for microorganisms.

Swelling and Dissolving

The fibre swells in 2% solution of benzoic acid, salycylic acid and phenol.

Alcohols, Ketones, soaps, detergents and drycleaning solvents have no chemical action on polyester fibres.

Chemical Resistance

Polyester fibres have a high resistance to organic and mineral acids. Weak acids do not harm even at boil. Similarly strong acids including hydrofluoric acids do not attack the fibres appreciably in the cold.

Uses of Polyester

1. Woven and Knitted Fabrics, especially blends.
2. Conveyor belts, tyre cords, tarpaulines etc.
3. For filling pillows
4. For paper making machine
5. Insulating tapes
6. Hose pipe with rubber or PVC
7. Ropes, fish netting and sail cloth.