Down feathers, have a short rachis that looks more like a stem than a trunk. Long barbs extend out of the top. But unlike outer-feather barbs, down barbs aren’t stiff. They are soft and flexible, as are their barbules. They billow out in all directions and overlap to form fluffy spheres. Each barbule is more than 10 times thinner than a strand of human hair, but a single feather may contain miles of them. The wispy spheres are ideally shaped to splay out and clump together. They fill up empty spaces where air could pass through. They create a cohesive barrier that traps in an insulating layer of air. The down also blocks cold winds from sweeping away the bird’s heat. Because the feathers are flexible, they don’t break when they are compressed, and they quickly fluff out again. The feathers of other types of ducks and geese have similar features.
Down feathers, have a short rachis that looks more like a stem than a trunk. Long barbs extend out of the top. But unlike outer-feather barbs, down barbs aren’t stiff. They are soft and flexible, as are their barbules. They billow out in all directions and overlap to form fluffy spheres. Each barbule is more than 10 times thinner than a strand of human hair, but a single feather may contain miles of them.
The wispy spheres are ideally shaped to splay out and clump together. They fill up empty spaces where air could pass through. They create a cohesive barrier that traps in an insulating layer of air. The down also blocks cold winds from sweeping away the bird’s heat. Because the feathers are flexible, they don’t break when they are compressed, and they quickly fluff out again.
The feathers of other types of ducks and geese have similar features.
羽絨保暖是因為會把存有熱力的空氣分子抓住在絨頭末端 同油脂無關的。 仿生而成的人造纖維就是而家的抓毛外套了。 另一種仿生而成的保暖衣物就是中空纖維例如杜邦或者3m 模仿的是北極熊的中空毛髮。 最古老的保暖衣物就是pp。