Liquid Absorption Capacity - Hydrophilicity Testing

Liquid Absorption Capacity - Hydrophilicity Testing

Hydrophilicity essentially means "Water Severity", on the other hand is the material's ability to absorb water. The hydrophilicity test is to test the water absorption of the material.

Liquid suction time
The time required for a sample of the absorbent material to be fully wetted by the test liquid, ie the time required for a liquid to penetrate the internal structure under the specified conditions

Liquid absorption capacity
The liquid absorbed by the unit mass of the test absorber is expressed as a percentage of the mass of the test absorber under the specified conditions and after a specified period of time;

Liquid flexibility rate
The capillary measure of the test material, ie the velocity at which the liquid is transported to the fabric by capillary action

Fluid transfer behavior of textiles and other materials produced is important for the performance of a product during production processes and end use. The liquid transfer properties of the raw material used in the production of the material are greatly influenced by the liquid absorption properties, yarn production method, surface forming technique and fabric structural parameters and finishing processes applied to the fabric, garment comfort and some technical textile applications (medical textiles, geotextiles, agrotextiles, etc.). is a feature to consider.

In parallel with the developments in textile and other technologies, people's living standards have increased and garment selection criteria and expectations from the garments they use both in work and leisure time have increased.
Among these expectations, the thermal component of comfort, which is at the forefront, is directly related to the fluid transfer properties of the fabrics forming the garments, and it is desirable to remove the sweat formed in the body in a short time, especially during intensive activity. Therefore, in recent years, especially in the functional garments (sport, military, protective, etc.), the production of fabrics with different properties of fabrics to change the fluid transfer properties (liquid absorbing or liquid repellency) has been made to work. The liquid transfer properties of the products are an important factor affecting their performance for many technical textile fields, whose development has accelerated in recent years. Technical textiles such as bandages, surgical kit covers, geotextile and agrotextile products in contact with the soil and packaging textiles used in medical field other than garments are expected to have liquid absorbing or liquid repellency and breathability properties according to the field of use. In order to gain these properties, the specified objectives can be realized with the production parameters and processes selected from the raw material in the production processes, especially in the finishing process. The absorption theories that play a decisive role in the communication of textile materials with liquid are summarized below.

This test is applied to fabrics which require high water absorption. For example; such as medical fabrics, underwear fabrics, terry fabrics.

It is tested in two ways;

1: Determination of water absorption by immersion in water.
2: Determination of drop time by drop of water.

Determination of Water Absorption Degree (Water Absorption)
Determination of Water Absorption Ability by Height
Measurement of Water Propagation Rate

Theories of Absorption
The theories of absorption by examining the effective parameters in liquid transfer events in textile materials are explained briefly below.

Effect of hydrophilic groups
In the case of absorption, an interaction occurs between the molecules of the water and the structure of the fiber, so that natural fibers (including regenerated fibers of natural origin) with hydrophilic groups that interact with water absorb the liquid because they absorb water, and synthetic fibers interact with a small number of water. liquid absorption capacity is very low.

Direct and Indirect Bound Water Molecules
During the first interaction between the textile material and water, the water first adheres to the hydrophilic groups. The water molecules then either attach to hydrophilic groups or attach to the previously attached water molecules to form a new layer. Water molecules bound directly to hydrophilic groups are tightly bound and have limited movement. Indirectly connected water molecules whose molecular settlements are more irregular have a more loose structure and move more easily.

Absorption to crystalline and amorphous regions
In the crystalline regions of textile materials, the fiber molecules are tightly packaged and regular. Active groups formed cross-links between molecules. Therefore, the penetration of water molecules into the crystalline region is not easy and some of the cross-links between the active groups have to be broken in order to absorb water. Moisture absorption of a material will give an idea about the crystalline and amorphous region ratios of the structure.

Molecular Explanation of Hysteresis
Crystalline regions have an effect to mechanically inhibit water penetration into the structure and to reduce the number of hydroxyl groups suitable for bonding. As the absorption increases, the cross-links break and leave their place to water molecules. Depending on the resistance mechanism of the fiber structure to the change, the breaking and regeneration of the cross-links takes place in the form of a hysteresis, which leads to the formation of liquid absorption / desorption hysteresis.

Limit Inflatables
Although glucose and cellulose have a chemically similar structure, their interaction with water is very different; cellulose shows a certain rate of swelling while glucose dissolves in water. The limit swelling results from the penetration of the liquid into the amorphous parts of the structure or between the fibrils and its inability to penetrate into the crystalline regions.

You can work with our laboratory EUROLAB for liquid absorption capacity hydrophilicity tests.