What Is The Air Permeability Test Of Fabric
At present, the commonly used air permeability test standards mainly include ASTM D737 1996 (Test method for air permeability of textiles), 1S0 9237 1995 {Determination of air permeability of textile fabrics", GB/T 5453 1997 "Determination of air permeability of textile fabrics" and JIS L1096 1999 ( Textile Air Permeability Test Method". Among them, GB/T 5453 1997 is equivalent to ISO9237 1995.
JIS L1096 1999 is divided into method A and method B. Method A uses a Frazier-type (Frazir) air permeability tester with a pressure difference of 125 Pa and measures the average value for 5 times; method B uses a Gurley-type (Gurley) air permeability The tester measures the time it takes for 300 mL of air to pass through the fabric under a specific pressure difference. The air permeability is expressed in time, and the unit is seconds. This method is suitable for wool fabrics. Since JIS L1096 requires the use of specific instruments, it is not commonly used in daily quality testing.
The commonly used test methods for air permeability of textiles are ASTM D737 1996 and GB/T 5453 1997.
Because air leakage will affect the test results of fabric air permeability, measures to prevent air leakage are mentioned in each test standard, requiring the use of sample fixtures and rubber gaskets. The rubber gasket is easy to age and deform after repeated use, which will affect the test results and should be discarded. The sample holder is suitable for knitted fabrics or fabrics that are easy to stick to the test head, not for heavy or stiff fabrics. When there is a difference in air permeability between the front and back of the test fabric, the side with less pressure should face down to prevent air leakage. If you want to obtain the air permeability of the fabric, you can cover the sample with an airtight cover, and measure the air leakage and the air flow through the fabric respectively.
(1) Each textile air permeability test standard is different in terms of scope of application, test area, pressure difference and test conditions. Tests show that the test results of ASTM D737 1996 and GB/T 5453 1997 show a high correlation of 1.25 times.
(2) The air permeability of cotton, hemp, wool and other natural fibers and protein fiber fabrics is better than that of synthetic fiber fabrics such as nylon and polyester. Generally, the order of fabric air permeability is: perforated fabric>satin weave>twill weave>plain weave; the fabric's floating length increases, and the fabric's air permeability also increases accordingly.
(3) Liquid ammonia finishing can improve the air permeability of the fabric, while three-proof finishing will obviously reduce the air permeability of the fabric. After the fabric was washed 5 times, the air permeability of the fabric changed significantly, and then gradually became flat; after 30 times of washing, the air permeability of the fabric tended to increase. The air permeability of the fabric after baking was increased compared with that before baking.
