Drying clothes in the sun is thought to be healthy, and it’s easy and energy efficient. Clothes that are dried in the sun smell fresh, but there are some clothes that are not suitable for drying. Bath towels are one example.
Why is a towel dried on a line as hard and rough as beef jerky? It’s a question that has baffled scientists for a long time, but a team of researchers from Hokkaido University in Japan has solved the mystery. They claim to have cracked the “key to air drying” and in the process have learned something important about water.
Speaking of which, most fabrics that are not made of plastic (with the exception of silk and wool) are based on plant materials. Cotton is a fluffy white fiber from the seeds of a small shrub, while rayon, Modal, fibrin, acetate, and bamboo are all derived from wood fibers. Plant fiber is an organic compound that helps maintain the firmness of plant cell walls, and fiber is very absorbent, which is why we use cotton to make towels that feel better than polyester. Water molecules attach to cellulose and stick along it through a process called capillarity, which can even defy gravity and pull water to the surface.
Because water is a polar molecule, meaning it has a positive charge on one side and a negative charge on the other, water is easily attracted to charge. The team says the structure of individual crossed fibers in air-dried fabrics like cotton towels actually “binds water”, or water behaves in a unique way because it is able to attach to something on its surface that acts like a sandwich, bringing the fibers closer together. The latest research appears in a recent issue of the Journal of Physical Chemistry.
The team carried out experiments showing that binding water to the surface of cotton fibres creates a kind of “capillary adhesion” between the tiny fibres. When these strings stick together, they make the fabric harder. Hokkaido University researcher Ken-Ichiro Murata noted that the bonded water itself exhibits a unique hydrogen bonding state, unlike ordinary water.
Researcher Takako Igarashi said: “people think, can reduce the friction between the cotton fiber fabric softener, however, our research results show that will promote the cotton fiber cotton towel of hydration hardening, it offers a new perspective for the understanding of the principle of operation of fabric softener, help us to develop better preparation, formula and fabric structure.”
Post time: Jun-24-2022