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Wednesday, October 31, 2018

DIMENSIONAL CHANGES OF FABRIC AFTER HOME LAUNDERING (AATCC 135)

OBJECT:
This procedure describes the process for determination of dimensional changes of fabrics when subjected to home laundering process.

Definitions:
      ·         Dimensional Change: Percentage change in length and width of fabric specimen when subjected to specified conditions.
      ·         Growth:  Dimensional change result in increase in length and width of specimen.
      ·         Shrinkage:  Dimensional change result in decrease length and width of specimen
      ·         Laundering: A process intended to remove soils and/or stains by washing with detergents or soap solutions and normally includes rinsing, extraction and drying.

Apparatus and Equipment:
      ·         Automatic Washing Machines and Tumble Dryer
      ·         Ballast of 920mm x 920mm (36” x 36”)
1.       Type 1 – hemmed pieces of bleached cotton sheeting, or
2.       Type 3 – 50/ 50 polyester/ cotton bleached plain weave
      ·         Measuring Devices
1.       Steel ruler marked in millimeters, tenth of an inch, or 
2.       Digital Imaging System
      ·         Scale with weighing capacity of 5kg (10lbs)
      ·         Iron, with maximum temperature at least 200°C (390°F)
      ·         Timer
      ·         Overlock machine

Reagents and Consumables:
      ·         1993 AATCC Standard Reference Detergent (Powder) or New Ultra Tide Powder Detergent with Original Scent or Original Tide with Acti-Lift Crystals.
      ·         Indelible ink marking pen or other marking devices (i.e. Tex marker)
      ·         Sewing thread

Sampling and Preparation:
      ·         One representative specimen of each sample to be tested is required.  
      ·         Fabrics that are distorted in their unlaundered state due to faulty finishing may give deceptive dimensional change results when laundered by any procedure should be taken out.
      ·         Avoid use of the sample area within ten percent of the sample width. Identify the length direction of the specimens before cutting out the sample.

Conditioning:
      ·         The specimens are conditioned at standard atmosphere of 21 ± 1 °C (70 ± 2 °F), 65 ± 2% RH for at least 4 hours prior to testing.

Marking:
      ·         Size of Specimen 15” x 15”(38 cm x 38 cm)

AATCC 135

Weighing:
      ·         Weight the specimen and enough ballast to make a 4.00 ± 0.25 lb loads. An alternative load size of 8.00 ± 0.25lb may be used.

Washing:
      ·         The washing cycle, water level and water temperature on the washing machine are set according to specifications in Tables I below or as per the care instruction.

AATCC 135

      ·         The temperature of water must comply with that required by specifications listed in Table I. Use a thermometer to measure the water temperature.  Whenever needed, add hot or cold water to the water bath to adjust to the appropriate temperature.
      ·         The washing machine is switched on.
      ·         The washing machine is filled to the 18 ± 0.5 gal water level and adds 66 ± 1.0 g of 1993 AATCC Standard Reference Detergent or 52.8 ± 1.0 g of New Ultra Tide Powder Detergent /Original Tide with Acti-Lift Crystals.
      ·         Agitate the water briefly to dissolve detergent.
      ·         Add the specimens and ballast into the washing machine. Set the washer for the selected washing cycle and time.
      ·         The door of the washing machine is needed to be closed.
      ·         The specimens and ballast are removed from the washing machine at the completion of washing cycle.

     DRYING:
     Specimens with the wet ballast are removed from the washing machine and are dried as follows: 
     NOTE: The drying machine is operated for 45 minutes or until dry. 
     NOTE: The specimens and ballast are removed immediately after drying.

     Conditioning and Restoration:
     After the completed washing, drying and ironing interval, the specimens are conditioned at standard atmosphere of 21 ± 1°C (70 ± 2°F), 65 ± 2% RH for at least 4 hours prior to measurement by laying fabric flat in perforated trays.
    
     Measurement and Calculation:
n   After conditioning, each test specimen is laid without tension on a flat smooth, horizontal surface.
     
          Calculate length and width averages separately to the nearest 0.1% for each direction.
The Calculation is as follow:

AAtCC 135
     Where,
     A = Original dimension
     B = Dimension after laundering
     DC = Dimensional change

     A final measurement smaller than the original measurement results in a negative dimensional change which is shrinkage.  A final measurement larger than the original measurement results in a positive dimensional change which is growth.

Sunday, October 28, 2018

Tear Properties of Fabrics (ISO 13937-2)

Objective
In this article we will see how to determine the tear properties of fabric in ISO 13937 part-02 method.

Definitions
Gauge length: Distance between the two effective clamping points (grips) of a testing device is known as gauge length.

Equipments       
  • CRE (constant-rate-of-extension) machine such as Titan
  • Clamping device, including the two jaws of the machine. The width of the jaws could preferably be 75 mm but not less than 50 mm.
Test Specimen
From each sample two sets of test specimens shall be cut, one set in the warp direction and one in the weft direction. Each set shall consist of at least three to five test specimens.

  • The test specimen should be a rectangular strip (200±2) mm long and (50±1) mm wide.
  • A longitudinal slit of (100±1) mm in length should be made beginning from the center of the width.
  • Mark the end of the tear (25±1) mm from the uncut end of the strip to indicate the position of the tear at the completion of the test.
ISO 13937-2

General: After wash this test is not applicable so the test should be performed before wash.
Treated denim: The denim which is scrapped or chemical treated should be tested before and after 3 washing & drying cycles.
Test only the treated and risky parts of denim, as for example; scraping, local bleaching. Several samples might be needed for testing.

ISO 13937-2
Non-washed denim sample preparation 
Testing Procedure 
  • The machine should have following settings: a. Gauge length: (100±1) mm b. Rate of extension: (100±10) mm/min
  • Clamp the test specimen in the jaws, with one leg in each of the jaws and the cut aligned along the center lines of the jaws. The uncut end of the test specimen should be remained free. Avoid pretension when the test starts.
CRE Machine
Testing in CRE Machine-Titan
  • Start the test and continue the tear to the mark near the end of the strip (point 1 in Pic 1). The tear force shall be recorded in newton and be calculated electronically. Observe whether the tear proceeds along the direction of force and whether any threads slip out from the fabric rather than being torn. The test is correct if there is; a. no slippage of threads out of the fabric; b. no slippage in the jaws; c. the tear is completed and preceded along the direction of application of the force. Other results should be discarded.
  • The test result is only valid if a minimum of three test specimens per set are correct. 
Results
 State following in the test report:
  • For denim: Report the lowest received tear force value across-warp and across-weft.
  • Number of test specimens rejected and reasons for this.
  • Any deviation from the given procedure (e.g. cross-wise tear)

Friday, October 26, 2018

Tearing strength of Textile Fabrics

Tearing strength of fabrics by falling pendulum type (Elmendorf) apparatus (ASTM D 1424)

Field
This procedure only applicable to woven fabrics (All types)

Purpose
This procedure describes the process for determining the force required to produce a single-rip tear starting from a cut in a fabric using a falling-pendulum (Elmendorf) apparatus.

Definitions
Tearing strength: The capacity of a fabric to withstand the tearing force required to produce tear after its initiation.

Apparatus and Equipment

  • Falling-Pendulum (Elmendorf) type tester.
  • Cutting die or Template (see Figure 1), the improved die model shown in Figure 1(a) has two new features not found in the original model, Figure 1(b), namely a cutout for the bottom of the specimen to aid in centering it in the clamps, and (optional) provision for cutting the 20.0 mm (0.75 in.) slit prior to inserting the specimen in the tester.
Elmendorf apparatus

Preparation of Test Specimens
  • From each sampling lot, 4 specimens are taken from the machine (warp) direction and 4 specimens are taken from cross-machine (fill) direction.
  • When cutting the woven fabric specimens, align the yarn running in the short direction parallel to the die such that when the slit is cut, the subsequent tear will take place between these yarns and not across them.
  • The specimens are conditioned at standard atmosphere of 21 ± 1°C (70 ± 2°F), 65 ± 2% RH for at least 4 hrs prior to testing.
Test Procedure
  • The pendulum is positioned to the starting position.
  • One specimen in each direction should be pretested to determine the pendulum weight to be used prior to testing three specimens for each direction.
  • The long sides of the specimen are placed centrally in the clamps with the bottom edge carefully set against the stops and the upper edge parallel to the top of the clamps.
  • The clamps are closed, and the specimen is secured approximately the same tension on both clamps. If necessary, the pressure should be adjusted to prevent fabric slippage occurrence during test.
  • The specimen should lie free with its upper area directed toward the pendulum to ensure a shearing action.
  • Using the built-in knife blade a 20 mm (0.787”) slit is cut in the specimen extending from the bottom edge and leaving a balance of fabric 43.0 ± 0.15 mm (1.69 ± 0.005”) remaining to be torn.
  • Record if the tear was cross-wise to the normal (parallel) direction of tear and report that specimen, or that sample, as applicable, as untearable.
  • The torn specimen is removed, and test must be continued until three tears are recorded for each test direction.

Tuesday, October 23, 2018

Breaking Strength and Elongation of Textile Fabrics: Grab Test (ASTM D5034)

Scope
To determine the effective strength of the fabric in use that is the strength of the yarns in a specific width together with the additional strength contributed by adjacent yarns.

Definitions
  • Grab test a tensile test in which the central part of the width of the specimen is gripped in the clamps.
  • Tensile strength of a yarn or fabric is defined as a maximum load that it will endure without breaking when subjected to uni axial tensile loading.
Apparatus and Equipment
  • Constant rate of extension machine (CRE): With operation at a speed of 300 ± 10 mm/min (12 ± 0.5 in/min).
  • Each clamp shall have a front (top) jaw face measuring 25 ± 1 mm (1.0 ± 0.02 in.) perpendicular to the direction of the application of the force, and shall be 1.0 in. x 1.0 in. rubber coated jaws parallel to the direction of the application of the force.
  • The back (bottom) jaw face of each clamp shall be 1.0 in. x 2.0 in. coated jaw.
Sample Preparation
  • Three lengthwise specimens and three width wise specimens are taken from each sample fabric.
  • Each specimen 100 ± 1 mm (4 ± 0.05 in.) wide by at least 150 mm (6 in.) long is cut with the long dimension parallel to the direction of testing and force application. In general, no two specimens cut parallel to the warp should contain the same set of warp ends, and no two specimens parallel to the weft should contain the same weft yarns. Unless otherwise specified, do not cut specimens closer than 1/10 of the width of the fabric from the selvedge.
  • A line is drawn on the specimen, which is parallel to the long direction (and along a yarn of woven fabric) and located 37 ± 1 mm (1.5 ± 0.02 in.) in from the edge of one side of the specimen.
Test Procedure
  • Dependent on the type of equipment used, and the software that is installed, the machine should be operated following the manufacturer’s guideline. If the machine is software equipped, select the appropriate program to run.
  • The distance between the clamps (gage length) should be set at 75±1mm (3.0 +/- 0.05 in). NOTE: The force range of the testing machine for the break to occur should be selected between 10 and 90% of full-scale force.
  • The specimen is mounted such that the longer dimension of the specimen is tested. One side of a specimen is placed in the upper clamp and locked in place. The side of the jaw has to be along the previously marked line. The clamping area must be approximately 1 in. from the top edge of the specimen.
  • The other side of the specimen is placed to the lower clamp. A tension of approximately 0.37 lb force (not to exceed 0.5% of the full-scale load) is applied by pulling down the specimen. While the specimen is held taut the bottom clamp is locked.
  • "START TEST" is pressed to start testing.
Breaking strength of textile fabrics

  • Any break occurring within 5 mm (0.25 in.) of the jaws which results in a value below 50 % of the average of all the other breaks should be discarded. If a fabric manifests any slippage in the jaws or if more than 25% of the specimens break at a point within 5 mm (0.25 in.) of the edge of the jaw, modification of jaws can also be accepted. For example, the jaws may need to be padded; or the fabric may need to be coated under the jaw face area; or the jaw face may need to be modified etc. Those modifications should be stated in the report if applied. 
Analysis of Data 
  • The average of observed breaking load and elongation is recorded directly from the machines or the computer for all acceptable specimens.