According to its design and engineering, microfibers can be very different from each other.

Focusing on the most common cleaning textile microfiber, the bicomponent polyester (PET) -polyamide (PA, Nylon) pie wedge microfiber, here is short explanation of its physical properties:

+ Water absorption

Liquids are subject to the effect of surface tension which is the result of different intra molecular forces, and especially the Van der Waals forces. All liquids' molecules undergo cohesive forces between them which confers them this liquid physical state. However, molecules at the surface are subject to stronger cohesive forces than molecules down into the liquid since there are no other cohesive forces coming from above to compensate those cohesive forces coming from beneath the surface. Being bound to each other more strongly, surface molecules act as a film, making it more difficult to move an object through the surface than moving it when completely submersed. Water tension is what can make a needle float in a glass of water or what allows water striders to move on the surface of a pond.

Surface tension contributes to what is called the capillary effect, which takes effect when wicking away some liquid and can be observed when putting a dry sponge on a water puddle . Technically speaking, it occurs when the adhesive intermolecular forces between a liquid and another surface (in our previous example, respectively water and sponge) are stronger than the cohesive intermolecular forces of the liquid - In other words it is a mere power struggle! When adhering to the sponge surface, water molecules, because of their surface tension, stick together. Besides, because of the constant motion of liquid's molecules, new water molecules are consistently getting in touch with the sponge surface, progressing further on it... until the sponge is completely soaked. In some materials, such as a vertical glass tube, water is being pulled up until the weight of the lifted quantity, which causes a superior gravitational force, overcome the intermolecular forces of surface tension. The narrower the tube, the higher water can be drawn into it since a smaller mass of water is exposed to the surface allowing adhesive and cohesive intermolecular forces to combine and overcome gravity. Some materials which are water-repellent, such as Teflon, can prevent the capillary action. In that case the cohesive intermolecular forces of water are stronger than the adhesive forces with the Teflon surface, which prevent water from sticking to the surface .

To sum up, capillary effect's efficiency depends on the kind of the surface material and on the available surface in a given volume: the more the surface of a hydrophilic material available in a limited volume, the more efficient should be the capillary effect. Sponge remains the best example in this respect.

Why are microfibers absorbent?

Cleaning microfibers are engineered in such a way as to make them very sensitive to the capillary effect. The action of splitting microfibers is a clincher as it releases the polyamide star shaped core of the fiber, which is rather hydrophilic, while multiplying the number of strands available on a same volume. It thus proportionally increases the total added surface of all the fibers available and hence enhances the sorption properties of the microfiber fabric.

Weaving patterns are also important for thatpurpose as a very tightly woven polyester microfiber fabric will at first prevent water from soaking in since polyester is more water-repellent (which makes it efficient for clothing). Cleaning mops are thus woven with specific patterns that allow a high exposition of the fibers, especially the polyamide core, to the surface in order to maximize absorption .

The capillary action is also mechanically increased by the scrubbing movements during cleaning. On average, a can retain up to 8 times its weight in water. Once inside the microfibers, water will be distributed quite fairly between fibers since polyester, which generally constitutes most of the fibers, is rather hydrophobic and won't accumulate much water molecules on its surface. This property of PET microfibers prevent the fabric from soaking (unless completely submerged) and make it is easier to dry since water on the fibers' surface evaporates more quickly. Doing so, it also prevents the growth of bacteria inside the fabric. Generally,

moisture regain

of polyester is around 0,4%, polyamide around 4,5% and cotton around 7%.

When sweeping a wet surface, microfibers will absorb most of the liquid, but it will also spread some along the surface in a very thin layer, which, in case of water, evaporates almost immediately.

+ Dust trapping

Mechanical properties of microfibers

Once split, the cross section of regular cleaning microfibers will take different forms according to their composition. Polyester fibers will take the shape of wedges whereas nylon fibers will take the shape of stars with very thin branches (less than 1 micron in thickness). These angular forms have a much more efficient impact when cleaning a surface than regular round shaped fibers. The fibers' angles can lift the smallest dusts and even some bacteria. Besides the little space created between fibers after their splitting is narrow enough to trap all those particles . Each kind of fibers acts in fact as a microscopic tool with specific features that in an answer to specific needs

While using damp cleaning microfiber fabrics

Wetting a surface provokes an association of water and dust particles while wiping it with a cleaning microfiber mops achieves to absorb the liquid and trap the dusts inside the fibers. There again, surface tension of water is involved in retaining the dust particles and make them stick to the fibers' surface. Those particles are, in turn, trapped between the strands of the microfiber.

While using dry cleaning microfiber fabrics

Static electricity is one of the first electrical effects to have been studied. Ancient Greeks discovered that rubbing some materials against each other could make them attractive to small particles. This effect is explained by an imbalance thus created in the amounts of positive and negative charges found within the surface of an object. Static electricity occurs when two object with an opposed charge are brought close to each other so as to create an electric field. This electric field is responsible to many properties and can be compared, to some extent, to a magnetic field. The bigger the gap between the two opposite charges, the more static electricity. This gap is measured in volts and often involves high voltage. When created by human activity, static electricity can range up to several thousands of volts. Everyday life has a broad range of electrostatic manifestations, from the small discharge one can get while gripping a doorknob to the phenomenon of lighting during a storm.

Static electricity accumulated while putting two insulated surfaces into contact is known as triboelectric charging and depends on different parameters. The more surfaces are put into contact, the more they accumulate a charge. In this respect rubbing allows a repeated contact with few movements and further increases the voltage. According to the materials, the charge accumulated will be either positive or negative, whereas other materials do not accumulate charges at all. Triboelectric series list materials according to their charging polarity and capacity: