"Feather keratin occurs in a 'b-sheet' configuration which differs from the a-helices that occur in mammalian keratins. . . We have measured the properties of individual down feathers from ducks, geese and penguins and found that their properties are similar to flight feathers and, indeed, the man-made polymers used in artificial insulation fibres. The message is that the architecture of down feathers is probably more important than material properties in determining their advantages over synthetic materials. . .Recently, we have begun to explore the toughness of feather keratin by using instrumented clippers and scissors. The fracture toughness of β-keratin has proved to be very high, around 10 kJ m-2." (Bonser 2007)
Comparison of keratin structure in down feathers and mammal hair. Artist: Emily Harrington. Copyright: All rights reserved. See gallery for details.