Page 7 - Curriculum Visions Dynamic Book

See Vol. 5: Glass to find out more about glass fibres.
See Vol. 6: Dyes, paints, and adhesives for more on dyeing fibres.
(Below) Hair is produced inside a special group of cells that make up the hair follicle. It pushes outwards through the skin.
Fibre qualities
All fibres have qualities that make them useful. Nearly all fibres are strong when pulled. They are said to have good tensile (pulling) strength. Fibres are also flexible, meaning they can be bent without breaking, and many are elastic, meaning they will stretch when pulled and then go back to their original size when released.
But many fibres also have limitations. For example, some will melt at low temperatures. Others will not melt but decompose to black carbon, a process called charring. Some fibres absorb water, swell, and get heavy when wet. They may also become weaker when wet. Others do not absorb water at all and so are difficult to dye with the more common water-based dyes. Some natural fibres
are readily attacked by bacteria, fungi, or insects. Others begin to decompose in light or heat.
This list of possible limitations should not suggest to you that fibres are really poor materials. It simply shows that you need to pick and choose the fibre you want for the purpose you have in mind. For example, cotton actually gets stronger when wet, and synthetic fibres do not suffer from attacks by fungus or insects.
Natural and artificial fibres
For thousands of years people have used natural fibres, that is, fibres from plants and animals.
When people deal with natural fibres, they are simply making the naturally occurring fibres into new patterns by the processes of spinning and weaving. They are mechanical processes. No chemical change is involved.
The world of artificial fibres (which includes, but is not the same as, synthetic fibres, as you will learn below) is little over a century old, but in that time the proportion of natural to artificially made fibres has changed from all natural to 70% artificial.
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