I'm Sure many have heard this word and even, perhaps, wondered how it looks and what it means. But not everyone is aware of the fact that knowledge about this physical property of materials can be useful in everyday life. That is why we will know him better.
Water Absorption – this property of a material to absorb and retain moisture from the air. Some may be confused by the letter “g” in the first part of the word, because we all know that the difficult terms associated with water, usually begin with the prefix “hydro”. But here we are talking of little else. Hygroscopicity takes into account the absorption of only that water which sprayed into the air as steam, and hence the prefix needed is quite different. “Hygro” means that the word is related to humidity. It's simple.
We discussed the definition and now it's time to find out what actually the word means. The air around us has a certain moisture content – this is indicated even in the weather forecast. Some fiber can absorb this water, often changing their properties. It is due to the hygroscopicity of clothes and shoes can get wet even without rain. In what cases is good and what-bad, find out below.
In this article we will focus mainly on tissues. But not only they are able to absorb moisture from the air. An indicator of the hygroscopicity of a material is often necessary to know the builders, furniture makers, manufacturers of sophisticated equipment and many others.
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For Example, we all know that wood has a porous structure, it increases its hygroscopic properties. Water penetrating the structure of the tree, and deforms it. That is why furniture made of wood is not practically installed in rooms with high humidity. To reduce the hygroscopicity can use special impregnation.
No less important, and the hygroscopic properties of the insulation used in the construction. The air trapped in the pores of the material, holds heat in the room. But if the insulation gets wet, it will instantly lose its basic properties. Therefore, the materials used for these purposes should have a minimum hygroscopicity. A perfect score is 0%.
All materials have various physical characteristics, such as density, strength etc. But for fabrics, which are then to turn into items of clothing, and other important properties – hygienic. They determine how comfortable clothing from any material.
Don't forget the thermal protective properties of the fabric. Is the ability to maintain normal body temperature at the time when it is cold outside. And about the last property we'll talk in more detail.
This figure refers to the hygienic properties of textiles, which, in turn, determine the comfort of a material to wear. Moreover, the requirements for clothing in many respects depend on its purpose.
Water Absorption – the most important property of sports uniforms or summer clothes. Increased temperature and body leads to sweating, which in turn creates considerable discomfort for the person. To get rid of excess moisture allows it is the high hygroscopicity. This property is a key indicator for manufacturers of everyday underwear.
What determines the ability of the fabric to absorb moisture from the environment? In the first place – from the fibres of which it is made. In addition, the importance is the presence of protective coatings and impregnations.
The Materials of which are made of fabric, can have different origins. There are natural fibers and synthetic. First, let's talk about the first. They are created by nature, though not without human intervention.
Wool, cut with a variety of animals, most often used for the production of warm clothing. It is one of the leaders among natural fabrics ability to absorb moisture. The hygroscopicity of the wool fibre is approximately 15-17%. But the absorption rate is relatively small.
This figure is much higher in many other tissues. For example, the hygroscopicity of cotton is only 8-9%, but he is able to absorb moisture much faster than wool. Another natural material-flax, obtained from the bast fiber. Itthe ability to absorb moisture can range from 12% to 30%.
The first type includes materials derived from natural compounds. A vivid example – viscose. Create it with the use of natural cellulose. For viscose fibres the characteristic strength, temperature resistance and high water absorption, equal to almost 40%.
Synthetic fiber is created from products of processing of oil and coal. These include the polyamides. These fibers create nylon, nylon and anid. The hygroscopicity of these materials is quite low, only 3-4%, but they retain their strength when stretching and is highly durable. Polyester fibers, which create the fabric of Dacron, have a high rate of heat resistance and resistance to light. But their water absorption is minimal – 0.4%.
Polyurethane fibers, which are the basis for lycra and spandex, do not have the ability to absorb moisture from the environment. From the foregoing it can be concluded that the hygroscopicity of clothes made of synthetic materials are much lower than things made of natural fabrics. But is it really a disadvantage?
Everything is relative. The same can be said about the raised topic. It is impossible to say that the hygroscopicity – that's good. Yes, it allows people easier to survive the heat, and athletes-to perform exercises in a more comfortable environment. But some fabrics excessive moisture can only do harm.
The example of insulation we have found that water reduces the insulating properties of the materials. In addition, some fabrics are deformed under the action of moisture – we all know how stretched after washing the Jersey. The same fate, only on a smaller scale may suffer some materials at very high relative humidity. Therefore, it is not always possible to tell with confidence that the hygroscopicity – is a plus. The question as to the applicability of a material.
In the 80-ies of XX century in the USSR was established GOST 3816-81. It contains a detailed description of methods for the determination of some properties of textiles, including water absorption. Here's how it is.
Experts take samples of tissue with a size of 5 × 20 cm and each placed in a separate Cup for weighing. The main objective of the experiment – find out how much water a material will absorb under certain conditions. For this Cup with the sample was placed in a desiccator in which humidity is 97-99%. 4 hours is the weighing of the sample, and then at a temperature of 105 to 109OWith dry material and determine its new weight.
The Rate of water absorption (N) percentage determined using the formula: N = (MW-MS) / MS x 100 where MV and MS are taking, respectively, the mass of wet and dry cloth.
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