Animal fibers are natural fibers mainly composed of certain proteins, such as wool, silk, etc. Alfa Chemistry supplies a range of high quality animal fibers and their composites.
Introduction
It is well known that animal fibers, such as silk, wool, hair, feathers, etc., are widely used in the textile industry. In recent years, with the exploration of natural fiber composites, animal fibers have also been used as reinforcing materials to study their potential in composites. Animal fibers are the second most important source of natural fibers in composite materials.
Common Category
Silk
Due to its structure and properties, the potential of silk is outstanding. It consists of highly structured proteins and a wide range of properties, namely high tensile strength, high elongation and chemical resistance. Silk comes from a variety of sources and its properties vary. Among them, mulberry silk (Bombyx mori) from silkworms and dragline silk (Nephila) from spiders are widely discussed and used.
Mulberry silk is the most commonly used silk and the only silk commonly used commercially. The two main components of mulberry silk are silk fibroin and sericin. Mulberry silk fibers are semi-crystalline, with a crystallinity between 38% and 66%. It shows submicron fibrous substructures with diameters of approximately 120 nm. These fibers can be used below 170 °C without fiber degradation, and thermal degraded at 250 °C. Silk fibroin is well-suited to resist various elements, which is reflected in its chemical stability. This fiber is stable to many chemicals, insoluble in most alcohols and acetone, resistant to weak acids, and less water-absorbing.
Properties of two types of silk [1]
| Fiber | Degree of crystallinity (%) | Maximum use temperature (◦C) | Thermal degradation (◦C) | Tensile Strength (GPa) | Extensibility (%) |
|---|
| Mulberry Silk | 38-66 | 170 | 250 | 0.6 | 18 |
| Dragline Silk | 20-45 | 150 | 234 | 1.1 | 30 |
Properties
- Hygroscopicity
Protein fibers are extremely hygroscopic due to the presence of hydrophilic groups (hydroxyl, carboxyl and amino groups) in protein fibers. - Dyeability
Protein fiber molecules contain basic amino groups (-NH2) and acidic carboxyl groups (-COOH), so they can be dyed with acid dyes and basic dyes. - Hydrolysis
Protein fiber molecules contain amide bonds, which are prone to hydrolysis under alkaline conditions. Therefore, animal fibers are unstable to alkalis, but relatively stable to acids.
Applications
In addition to routine applications in the textile and apparel industry, the potential of animal fibers in biomedical applications has been extensively studied. Silk protein, fibroin and sericin are processed into biomaterials due to their biocompatibility, biodegradability, excellent mechanical properties, heat resistance and UV protection. For example, mulberry silk is used in tissue engineering to produce scaffolds thanks to its biocompatibility, support for cell proliferation, and mechanical stability.
Microstructure of a silk filament: consists of long, thin fibrils [2]
References
- Sunil Kumar Ramamoorthy, et al. Polymer Reviews, 2015, 55(1), 107-162.
- S. Nivedita, et al. Journal of The Institution of Engineers (India): Series E, 2014, 95, 57–61.
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