The official moisture regain of major textile fibers:

Fibre Refining Moisture Regain Cotton 8.5% Polyester 0.4% Ramie 13% Polyamide 4.5% Wool 15-16% Vinyl 5% Silk 11% Acrylic 2% Viscose 13% Polyester 0% Polypropylene 0%


Textile materials include textile raw materials processed into textiles, textile semi-finished products, such as various fibers, slivers, yarns, fabrics, and the like. The hygroscopicity of textile materials is an important feature that relates to material properties and processing technology. The hygroscopicity of textile materials is usually expressed in terms of the moisture regain rate and the fixed moisture regain rate of the test of the normalized moisture regain of textile materials. These basic quality indicators play an important role in the commercial trade of textile materials, performance testing and in textile processing. Testing methods for measuring the regain of textile materials (1) Direct determination method (2) Indirect determination method.


Moisture regain and fixed moisture regain: The moisture regain of a textile material is the percentage of water absorbed in the sample to the dry weight of the sample. The moisture regain of textile materials varies from time to time and its weight varies. In order to eliminate the difference in weight caused by the different moisture regains and meet the needs of textile materials trade and inspection, the State has set a corresponding standard for the regain rate of various textile materials, which is called the nominal moisture regain, which is close to the standard temperature and humidity in value. The equilibrium moisture regain measured under conditions. It should be noted that the regulations on the regaining rate of textile materials in various countries are often based on their own actual conditions, so they are not completely consistent.

There are many ways to test the moisture regain of textile materials:

(1) Direct measurement method: Weigh the sample weight first, then remove the water, and then weigh the sample dry weight to calculate the actual moisture regain. According to the method of removing water, direct measurement methods include: oven method, infrared radiation method, high-frequency electric field heating method, vacuum drying method and hygroscopic agent drying method. The oven method and infrared radiation method are often used in industrial production. The advantage of the oven method is that the measurement results are more accurate. The disadvantages are slow speed and low efficiency. The advantages of the infrared radiation method are its high speed, high efficiency, and energy saving. The disadvantages are that the temperature is not easy to grasp and the measured results have fluctuations.

(2) Indirect measurement method: Indirect estimation of the moisture regain of the fiber is based on the relationship between certain properties of the fiber and the moisture regain. The advantage of this method is that it is fast and efficient, but the determination of the relationship between fiber-related properties and moisture regain rate still requires the use of direct methods. Indirect methods can be divided into resistance method, capacitance method, infrared absorption method and microwave method. In China, the moisture content of raw cotton is determined by the resistance method. The microwave method has the characteristics of rapid, continuous, non-contact, non-destructive, etc. It can be used for continuous measurement and automatic control. It is a new technology that is still under development.

The introduction of the common oven method: It is through the resistance heating in the oven, so that the temperature of the air inside the oven to a certain value, and throughout the drying to maintain this temperature, and then put the wet textile material samples Into the constant temperature oven for drying, so that the moisture in the textile material continuously evaporates in the hot air, and use the exhaust device of the oven to keep the hot and humid air out of the box, creating conditions for the continuous evaporation of the water content in the textile material. As the moisture content of the textile material continuously evaporates and dissipates, the weight is continuously reduced. When the weight is dried until it is constant, it is the dry weight of the textile material. At this time, the dry weight of the sample can be weighed by the method of heat weighing inside the box. Finally, the moisture regain of the textile material can be obtained according to the wet weight and dry weight of the sample. In the oven method, the drying temperature is set at 105°C±3°C for cotton, 105 to 110°C for wool and most chemical fibers, and 140 to 145°C for silk. Drying time is generally 90min.

In addition, the moisture regain of a textile material can be measured using a resistance wet method or the like. The resistive wet method determines the moisture content of a textile material based on the fact that the textile material has different electrical resistance at different moisture regain rates. For products with unstable moisture content, such as wool, raw silk, cotton, etc., in order to accurately calculate the weight of these commodities, the method of calculating by the conditional weight is commonly used internationally to determine the actual moisture regain of the product (water content). Rate) to calculate the weight of the goods clean, and then converted into a fixed moisture regain.

The formula is as follows: Common = [product actual weight / (1 + actual moisture regain)] ╳ (1 + nominal moisture regain) = product clean weight (1 + fixed moisture regain)


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