Comprehensive Guide on AATCC 20A Quantitative Analysis

AATCC 20A Quantitative Analysis (Test Method by American Associate chemist and colorist) is used to quantitatively determine moisture value, non-fibrous materials, and the ratio of fibers blended chemically and microscopically.

Firstly, let’s explain some definitions relative to the analysis.

Types of fibers

Moisture Content

Take weighing bottles to weigh samples to determine the moisture content of textile materials. Cut the sample weighing about 1 gram, and add it to the weighing bottles. Put the caps of weighing bottles and weight on the weighing scale. First, weigh empty bottles with caps and then add the sample to the weight again bottle with the sample. 

Weight of bottles: …………….

Weighing of bottles and sample: …………….

Put the weighing bottle into the oven and dry for 1.5 hours at 105 to 110 degrees, according to AATCC 20A (American Associate Chemist and Colorist).  After the time completion, put the cap immediately on the bottle, remove it from the oven, and put it into the desiccator to gain room temperature. After 30 minutes, weigh the bottle with the sample and put it into the oven again for 30 minutes. After time completion, remove from the oven and weigh again to find the accurate percentage of moisture content. Put the bottle again into the oven until the weight becomes stable and no further moisture is removed from the sample.

Now calculate the percentage by the formula

Moisture content= Initial weight – Final weight ÷ Total Weight × 100

Removal of non-fibrous materials (Cleaning of fibrous materials)

Weight the sample near 1 g and dry it in the oven at 105 to 110-degree temperature. Dry the complete sample and proceed to remove non-fibrous materials. Treat the sample with different chemicals according to the non-fibrous materials coated on it.

• Hydrochlorofluorocarbon is used to remove oil, wax, and certain fat materials. Dip the sample into the Hydrochlorofluorocarbon on the Soxhlet apparatus and wash to dry in the oven at 105 to 110-degree temperature.
• Use Ethyl Alcohol to remove soap materials from the fiber material. Extract the clean, dry sample with ethyl alcohol on the Soxhlet apparatus and wash to dry in the oven to remove non-fibrous material altogether.
• Aqueous treatment is used to remove nonfibrous material with water-soluble. Add the dry specimen into the water for 30 minutes at 50 degrees temperature for the solubility of the non-fibrous portion of textile materials. Stir simultaneously on the shaker for a fixed period. After three clear washes with water, the sample is dried in the oven at 105 to 110 degrees for further procedure.
• Enzyme Treatment is used to remove the starch finished from the textile materials. Dip the sample into the enzyme-prepared solution for the removal of starch. Wash the sample with water and dry it in the oven.
• Acid Treatment was used to remove the resin material coated on the sample. Prepare 0.1N HCL solution and add the sample. Heat at 80-degree temperature for 25 minutes. Shake and wash with water. Dry in the oven and proceed for chemical treatment.

Mechanical separations

Fibers have a physical appearance and can be separated manually. Fibers have more accurate values found in manual separation than in chemical treatment, according to AATCC 20a. Spandex fibers are added into the yarn, or within the yarn, we can separate it mechanically and report manual separation technique.

Most high-performance fibers, like Aramid, metal fibers, and rubber, are added into the single yarn formed and have no dissolution method.

Chemical Treatment Methods

• Method for Acetone (Acetate fiber) Prepare specimens that weigh about 1 gram, which is the ideal weight according to AATCC 20a (American Associate Chemist and Colorist). Cut into pieces to dissolve the fiber properly in a liquid solution. Weight the sample on a weighing scale, add the Clean, dry specimen into the engineer flask, and add 200 ml acetone. Shake properly to dip the sample into the solution. Now, it remained at 40 to 50-degree temperature for 25 minutes. After 25 minutes, decant the solution, add freshly acetone, and shake it. Wash the sample with water properly through a glass-fitted crucible and dry it in the oven at 105 to 110-degree temperature. Weight the residue and find the percentage of dissolved fiber (Acetate).
• Method for Hydrochloric acid The weight sample is 0.5 to .1.5 grams, and the portion of the representative part of the sample is nearly 1 gram. Take 20% solution of HCL, about 0.5 to 1.5ml according to sample weight. Put the sample into the flask and dip properly into the solution.  Please keep it for 5 minutes at 15 to 20 degrees temperature and shake vigorously to dissolve the sample. After the period, shake it again and keep it for 15 minutes. Decant the liquid and add more fresh hydrochloric acid to dissolve the fiber completely. Now, wash the residue with a filter crucible until gravity completely drains the liquid. Wash with water to remove the chemical properly and dry it in an oven at 105- to 110-degree. After drying, weight, the residue, and the percentage of dissolved fiber.
• Method for 59.5% Sulfuric Acid: Weight the sample between 0.5 to 1.5 g portion of fabric and record the weight of the clean, dry sample near about 1 gram. Add the sample into a 250ml flask and add 59.5% sulfuric acid solution according to weight. Add 0.5 to 1.5ml Solution according to weight and shake vigorously to dip the sample into the solution. Let stand the flask for 15 minutes at 15 to 25- degree temperature. Shake the solution and keep it for another 15 minutes to dissolve the fibers properly into the solution. After the third time, shake the sample and wash it through the filter crucible. Apply the suction until all the liquid drains by gravity, and then rinse with water to remove the acid. Also, wash with ammonia solution to neutralize the acid for clear washing and then wash with cold water. After washing, dry the sample in an oven at 105 to 110 degrees within 3 hours. Wight the residue and find the percentage of dissolved (Acetate, Rayon Viscose) fibers percentage: initial weight minus final weight divided by total weight and multiplied by 100.
• Method for 70% Sulfuric Acid (Cellulosic fibers) Weight the sample 0.5 to 1.5 grams from the representative portion of fabric. Record the weight clean, dry mass near 1 gram for the chemical treatment. Weight the sample on a weighing scale and add it to the 250ml flask. Add 70% sulfuric acid solution and shake vigorously to dip the sample properly. Let stand flask for 15 minutes at 15 to 25-degree temperature and shake it. Shake the flask for the second time and keep it for more than 15 minutes. Decant the solution and add a fresh sulfuric acid solution for the complete dissolution of fibers. Filter the solution with a filter crucible and apply the suction until the solution is completely drained under gravity. Wash with ammonia Solution to neutralize the acid solution. Now wash with cold water to completely remove acid from the residue. Dry in oven for 3 hours at 105 to 110-degree temperature. After drying weight, the residue and the percentage of dissolved (Cellulosic (Natural) Fibers).
• Method for 70% Sodium Hypochlorite solution (Wool, silk fibers) Prepare the sample between a 0.5-to-1.5-gram representative portion of the fabric. Weight the clean, dry specimen on a weighing scale, put it into the flask, and add sodium hypochlorite solution 0.5 to 1.5ml according to sample weight. Shake the flask and stand it for 20 minutes at a 25-degree temperature. Maintain the temperature by washing the flask with water and shaking it vigorously to dissolve the fiber properly. After the duration, filter the solution with a filter crucible and apply the suction until the solution is drained under gravity. Wash the residue with sodium bisulfate and water to remove the solution. Dry residues in the oven at 105 to 110 degrees temperature and weight are used to find the percentage of dissolved fiber (Wool, silk, etc.).
• Method for 90% Formic Acid (Nylon fiber) Weight the sample between 0.5 to 1.5 grams and record it as an ideal weight near 1 gram.  Weight the clean dry sample, put it into the 250ml flask, and add the 90% formic Acid. Shake the flask for 1 minute and stand it for 15 minutes at room temperature. Decant the solution and add fresh formic acid to dissolve the fibers properly. After a while, filter the solution with a filter crucible and apply the suction to drain the complete solution from the residues. Wash with cold water until residue is completely cleared and dry in the oven for 3 hours at 105- to 110-degree. After drying weight, the residue and the percentage of dissolved fibers (Nylon, Acetate).
• Method for Dimethylformamide (Acrylic, spandex fibers): Weight the clean, dry specimen between 0.5 to 1.5 grams and record weight near about 1 gram. Remove the moisture content and weight on the weighing scale. Put the sample into the flask and add dimethylformamide to dip the sample in the solution properly. Let it stand for 20 minutes at 98±1 degrees in a water bath. Decant the liquid and add fresh dimethylformamide for the proper dissolution of fibers. After the third time, add a fresh dimethylformamide filter by filter crucible and apply suction to drain the liquid by gravity. Wash it with water and dry it in the oven at 105 to 110-degree temperature for 3 hours. After drying, calculate the percentage of dissolve (acrylic, Elastane, mod-acrylic fibers, etc.) by the weight difference method.
• Method for Alkaline Methanol (Polyester fiber): Prepare the clean, dry sample between 0.5 to 1.5 grams and record the weight near 1 gram. Prepare the Alkaline solution by adding 9 grams of sodium hydroxide (Pellets) to 100 ml of methanol and make a homogenous solution after completely dissolving sodium hydroxide. Now heat the solution at 65 degrees and maintain its temperature. Put the sample into a well-maintained temperature solution and keep it for 5 minutes. Now, decant the liquid and filter it into a crucible. Apply the suction until all the solution is drained under gravity. Wash with water and dry in the oven at 105 to 110-degree temperature for 3 hours. After drying weight, the residue on the weighing scale and find the percentage of dissolved fiber (Polyester) by weight difference method.

Microscopic Analysis Technique

In this technique of AATCC 20a (American Associate Textile Chemist and Colorist), we can analyze the Fiber content of the following fibers blended with other fibers.

• Microscopic Analysis of Polyester Fiber
• Microscopic Analysis of Acrylic Fiber
• Microscopic Analysis of Cellulosic Fibers

 Microscopic quantification technique was used to find the percentage of Polyester Acrylic and other fiber fibers on the microscopic analysis techniques. This microscopic analysis separates the blend of two fibers (Polyester, Acrylic, etc.) to calculate their percentage in textile materials. This performance technique depends on the personnel’s experience in identifying the polyester fibers and counting properly on the microscope. Most of the fibers have similar morphology and minor differences in structure.  So, first of all, it is a big Challenge to identify fiber on a microscope when it is a blend of two or more two fibers. Use the stain color to identify fibers better. In microscopic analysis, we count the number of fibers and measure their diameter, which highly affects the fiber percentage by quantification method. Most of the Cellulose fiber blends, which have no chemical treatment, are analyzed using a microscope. Cellulosic fibers which are calculated by microscopic method, are:

AATCC 20A Quantitative Analysis Procedure 

Prepare the slide longitudinal view using a microtome or another device for microscopic polyester and acrylic fiber analysis. Take sample 2 into 2 inches and reveal the warp and weft side. Record the weight of the warp and weft side on a sheet in a microscopic analysis sheet on a pc. First, properly make a slide of warp side, cut the snippets by microtome, spread them on a slide, and disperse it properly. Make a homogeneous mixture of fibers to analyze on the microscope. After preparing the slide clearly, put the slide on the microscope stage and count the fiber of each fiber blend. Count minimum of 1000 fibers and also measure their diameter. Move from one point of the slide to the other side and then down the side and left side in a zig-zag manner. Microscopic Analysis of polyester (Pet) fiber is commonly used for laboratory research and development.

A————————————————————————————————————–B

D————————————————————————————————————–C

E————————————————————————————————————- -F

Now, make the Weft Yarn slide by microtome and spread it on the slide with liquid paraffin oil. Mix the fibers and make a homogenous mixture to analyze fibers from a microscopic view. Put the slide on the microscopic stage and then start counting. Measure the diameter of fibers and count the maximum fibers for better results. The accuracy of the result increased with the expert count of fibers and their diameters. Check each fiber diameter and measure the end side of fibers at which fibers have a smooth shape. Start counting in a zig-zag manner and calculate a result.

A—————————————————————————————————————-B

D—————————————————————————————————————-C

E—————————————————————————————————————–F

After the completion of microscopic analysis, find the percentage of fibers by the following formula:

Xi = is content of fiber, percent (by weight)

Ni = is relative number of fibers of type i

A= is average are of fiber i

Di= is mean diameter squared of fibers type i

Di π/4= is the mean are of round section fibers i

Si= is specific gravity of type I fiber

∑ (Ni× Ai ×Si) is sum of the respective N× A× S products for each fiber type in the blend

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