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Why are towels so hard after drying naturally

Why are towels so hard after drying naturally


A new study conducted by Kao Corporation and Hokkaido University showed that remaining on the cotton surface "bound water" (bound Water) allows a single cotton fiber cross-linking, which makes cotton products after air dry will harden. This discovery provides new ideas for us to understand the special performance of water on the surface of materials, and also provides new ideas for the development of clean technology.

If there is no softener when washing, and cotton towels that have been dried naturally will often become very hard. This is a common life phenomenon, but the mechanism behind it has always been a mystery. In previous research, Kao's research team believed that tethered water is the reason that makes towels hard. Tethered water is a special kind of water that exists on the surface of materials. The team came up with a theoretical model that believed that the bound water remaining on the cotton surface caused cross-bonding between single fibers through a phenomenon called capillary adhesion.

In a recent study published in The Journay of Physical Chemistry C , researchers published direct observations of bound water on the surface of cotton, supporting the model proposed by Kao Corporation. Kenichiro Murata of Hokkaido University participated in the research. They used atomic force microscopy (AFM) and special analysis techniques based on atomic force microscopy's infrared spectroscopy (AFM-IR) to analyze the bound water on the surface of cotton at the molecular level.

Atomic force microscope observation results show that a non-cellulose sticky substance exists on the cotton surface, and cellulose is the main component of cotton. This result strongly suggests that there is a viscous bound water, which causes capillary adhesion. In the spectrum experiment, two peaks appeared on the surface of naturally dried cotton, which proved the existence of bound water. No peak was observed after the surface moisture was completely removed from the cotton. In addition, the spectrum also showed that the bound water showed different states at the air-water junction and the water-cotton junction.

Kenichiro Murata said: "Experiments have shown that there is obviously bound water on the surface of cotton. The bound water helps to develop certain dynamic properties, such as the dry and hard effect caused by capillary adhesion. In addition, the bound water itself also behaves differently The unique hydrogen-bonded state of ordinary water. "Kao's Takako Igarash added:" In the past, it was thought that softeners work because they reduce friction between cotton fibers. But our findings suggest that bound water is involved The hardening process of cotton, which gives us a better understanding of how softeners work, can help us better study the formulation and system of softeners. "

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