What are the official moisture regain rates of textile fibers?

The official moisture regain rate of main textile fibers:

2%

Textile materials include textile raw materials and textile semi-finished products processed into textiles, such as various fibers, slivers, yarns, fabrics, etc. The hygroscopicity of textile materials is an important characteristic related to material performance and processing technology. The hygroscopicity of textile materials is usually expressed by the moisture regain and the normal moisture regain of textile materials. These basic quality indicators play a very important role in the commercial trade of textile materials, performance testing and textile processing. Moisture regain test method Test method (1) Direct measurement method (2) Indirect measurement method

Moisture regain and official moisture regain: The moisture regain of textile materials is the percentage of the amount of water absorbed in the sample to the dry weight of the sample. The moisture regain of textile materials varies, and their weights are also different. In order to eliminate the weight differences caused by different moisture regains, it meets the needs of textile material trade and inspection. To meet the needs, the country has stipulated corresponding standards for the moisture regain of various textile materials, called the official moisture regain, which is numerically close to the equilibrium moisture regain measured under standard temperature and humidity conditions. It should be noted that countries have different standards for moisture regain. The regulations on the public moisture regain of textile materials are often determined according to the actual situation, so they are not completely consistent.

There are many testing methods for the moisture regain of textile materials:

(1) Direct measurement method: first weigh the sample, then remove the moisture, then weigh the dry weight of the sample, and calculate the actual moisture regain. Depending on the method of removing moisture, direct measurement methods include: oven method ﹑Infrared Line radiation method, high-frequency electric field heating method, vacuum drying method and hygroscopic agent drying method are often used in industrial production. The advantage of the oven method is that the measurement results are more accurate, but the disadvantage is that it is slow and efficient. Low. The advantages of the infrared radiation method are fast speed, high efficiency, and energy saving. The disadvantage is that the temperature is difficult to control and the measurement results fluctuate.

(2) Indirect determination method: is using The relationship between certain properties of fiber and moisture regain can indirectly estimate the moisture regain of fiber.The advantages of this method are fast speed and high efficiency, but the determination of the relationship between fiber-related properties and moisture regain still requires the use of a direct method. Indirect methods can be divided into resistance method, capacitance method, infrared absorption method and microwave method. In China, the resistance method is often used to measure the moisture content of raw cotton. The microwave method has the characteristics of rapid, continuous, non-contact and non-destructive. It can be used for continuous measurement and automatic control. It is a new technology that is still developing recently.

Introduction to the commonly used oven method: It uses resistance heating in the oven to bring the temperature of the air in the oven to a certain value, and maintains this temperature throughout the drying, and then weighs the wet weight of the textile The material sample is placed in a constant temperature oven for drying to make the textile The moisture in the material continues to evaporate in the hot air, and the exhaust device of the oven is used to continuously discharge the hot and humid air out of the box, creating conditions for the moisture contained in the textile material to continuously evaporate and lose. When the weight is dried until it remains unchanged, it is the dry weight of the textile material. At this time, the dry weight of the sample can be obtained by using the method of thermal weighing in the box, and then the textile weight can be obtained based on the wet weight and dry weight of the sample. The resurgence of materials Rate. In the oven method, the drying temperature is 105℃±3℃; wool and most chemical fibers are 105~220℃; silk drying time is generally 90min. >

In addition, the resistance wet method can also be used to measure the resistance of textile materials. Moisture regain. The resistance wet method determines the dry moisture content of textile materials based on their different resistivities at different moisture regains. In order to accurately calculate the weight of unstable commodities, such as wool, raw silk, cotton, etc., the international method of calculating based on metric (Conditioned weight) is usually used, that is, the actual moisture regain (moisture content) of the commodity is measured to calculate The clean weight of the product is converted into the weight of the public moisture regain.

The calculation formula is as follows: Common quantity = [actual weight of product/(1＋actual moisture regain)] ╳(1＋official moisture regain rate)=clean weight of the product╳(1＋official moisture regain rate)

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