Natural Protein Fibers

Keywords

Poultry feather • Low density • Hollow structure • Honeycomb • Sound absorption

Poultry feathers are one of the most widely available, low-cost protein by-products. Unlike other protein sources, feathers have a unique hierarchical structure and low density that make them preferable for various applications. Figure 45.1 shows an image of the major parts of a feather. The central rachis or quill is a tough composite-like structure that extends throughout the length of the feather. Barbs are fibers that have lengths up to 4.5 cm in the case of chicken feathers. Barbules that have lengths of few mm are connected to the barbs similar to that of the barbs connecting to the quill as seen from the SEM image in Fig. 45.2 (left). A cross section of the feather quill and rachis reveals a unique honeycomb structure that is hollow as seen in Fig. 45.2 (right). This hollow structure is responsible for the lightweight and therefore low density (0.9 g/cm3) of feathers. In terms of physical structure, feather rachis and barbs were found to have typical diffraction pattern of a-keratin, but the orientation of the crystals in the rachis and barbs was found to be different [07Red]. Tensile properties of the chicken feather barbs are compared to those of turkey barbs and wool in Table 45.1. As seen from the table, the strength of the barbs is similar to that of wool but with lower elongation. It was reported that the chicken feather barbs could be hand twisted into yarns when blended with cotton fibers [07Red].

Fig. 45.1 Digital image of a chicken feather shows the main rachis or quill to which are connected the barbs that further branch out into barbules

Pe represents pennaceous and PI represents plumulaceous turkey feather barbs 1 g/den is approximately 115 MPa Reproduced from Reddy [07Red]

Reference

[07Red] Reddy, N.: J. Polym. Environ. 15, 81 (2007)