Fabric-on-fabric friction
By R. David Whitby | TLT Worldwide January 2024
This is important in determining the abrasion resistance, shrinkage and aesthetic properties of a fabric.
With the onset of winter in the Northern Hemisphere, with shorter days and colder weather, I started to wear my warmer clothes, including my sweaters.
However, I found that one of my sweaters was quite difficult to put on over one of my winter shirts. It did not slide easily over my shirt, and it was even more difficult to take it off. My sweater was made of 100% acrylic fabric, while my shirt was 100% cotton fabric. I wondered why the apparent friction between the different fabrics was so high.
I wrote in the November 2018 issue of TLT about “Friction in fabrics,” a column mainly about the internal friction within fabrics.
1 A fabric that has a low resistance to stretch and high friction against the skin or another fabric tends to stretch rather than slip. Conversely, a fabric that has lower friction and high tensile resistance tends to slip rather than stretch. A fabric that has high friction resistance and high stretch resistance tends to exert higher pressure on a person’s body, possibly causing discomfort.
There are hundreds of different types of clothing fabrics, all of which are made from a number of textile fibers. These fibers are generally grouped as acrylonitrile (acrylic), cotton, leather, linen (flax), mohair, nylon, polyester, rayon, silk, spandex (lycra), viscose and wool. Blends of these fibers also are used to create fabrics with different characteristics. The fibers are generally either woven or knitted into a fabric. These can range in texture from very smooth, like cashmere, to quite rough, such as tweed. They also can be very light duty, such as lace, or tough, such as canvas.
Knitting, unlike weaving, can produce loose yet extremely stretchable fabrics with almost no rigidity. It also enables the engineering of arbitrarily shaped two- and three-dimensional objects with different mechanical responses. However, the interplay between the constitutive yarn properties and local topological features of the stitches cannot be easily described by standard continuum mechanics.
It seems that the frictional properties of fabrics have been investigated mainly in terms of their sliding over a person’s skin or during their manufacture. But how are people going to know which type of sweater is likely to be difficult to put over which type of shirt?
Unfortunately, the complexity of the frictional properties of one fabric sliding over another is such that a significant amount of research effort is required to evaluate the degree of smoothness and roughness of each different fabric. This is because there are a multiplicity of factors that may possibly affect the frictional properties of fabrics.
Process variables, such as yarn construction, fabric structure and finishing treatments, are known to influence surface roughness, smoothness and internal and external surface characteristics. The types of fibers and their physical and chemical properties also will influence their frictional properties. This will be compounded when different types of fibers are mixed together to create a slightly different fabric. Fabric friction is an important factor in determining the abrasion resistance, shrinkage and aesthetic properties of a fabric. Yarn mechanical properties, fiber content and whether the fabric has been knitted or woven also will influence surface roughness or smoothness. Since friction is a surface phenomenon, fabric topography and the methods of determining coefficients of friction are likely to impact the perceived frictional properties of each type of fabric. Surface topography can be determined using different types of probes and microscopic examination, and this can be combined with subjective assessments of fiber feel and handle. Given hundreds of types of fabrics, the combinations of these variables appear to be endless.
Fortunately for me, I have another combination of acrylic sweater and cotton shirt, for which pulling on my sweater is quite easy. I guess most people will just have to use trial and error to find out which combinations of shirt and sweater are okay and which are not.
REFERENCE
1.
Whitby, D. (2018), “Friction in fabrics,” TLT,
74 (11), p. 136. Available
here.
David Whitby is chief executive of Pathmaster Marketing Ltd. in Surrey, England. You can reach him at pathmaster.marketing@yahoo.co.uk.