Structure and properties of cocoons and silk fibers produced by Hyalophora cecropia

Abstract

This paper shows that silk fibers produced by cecropia (Hyalophora cecropia) have similar tensile properties but different amino acid composition than that of mulberry (Bombyx mori) silk. The cecropia fibers are also much finer and have better strength and modulus than tasar silk, the most common non-mulberry silk. Cecropia is one of the largest silk producing moths and has similar lifecycle to that of mulberry silk but is easier to grow and produces larger cocoons than mulberry silk. In this study, we have characterized the composition, morphology, physical and tensile properties, and thermal behavior of the cecropia silk. Cecropia cocoons have a three tier structure and are larger (750 mg) than the cocoons produced by B. mori (650 mg). Fibers in the three layers in cecropia cocoons have tensile properties similar to that of B. mori silk but are finer (1.7-2 denier) and have higher strength (3.8-4.3 g/denier) and modulus (68-92 g/denier) than tasar silk.

Study on the microstructure of African wild silk cocoon shells and fibers

“…The cocoon shell holes of A. mimosae have adaptive significance by allowing fresh air exchange with inner cocoon atmosphere where the pupae reside. Reddy and Yang [16] also reported Copaxa multifenestrata (Saturniidae) have perforated construction with many holes on the surface of the cocoons.…”

Structure and physical properties of silkworm cocoons

“…For example, Zhao et al tested the tensile properties of B. mori cocoons and found them anisotropic with graded-layer properties [4,5]. The H. cecropia cocoons and fibres have also been measured by Reddy et al [6]. Blossman-Myer et al [7] have found that B. mori cocoon did not obstruct the exchange of respiratory gases between the pupa and the environment.…”

Physico-Chemical Studies on Raw and Processed Moth Caterpillar Silks from the Mega Biodiversity Hotspots of India

“…In case of undegummed tasar silk (Figure 1 b and c), the 2 diffraction peaks correspond to the crystalline nature of silk-II (2 = 16.3 and 17.2), and silk-I (2 = 19.9). A prominent diffraction peak at 2 angle of 19.9 corresponds to (201) plane (d-spacing of 4.43 Å) 7 . It has been reported that the amino acids glycine, alanine, serine and threonine constitute the crystalline regions in B. mori and common wild silks 7 .…”

“…A prominent diffraction peak at 2 angle of 19.9 corresponds to (201) plane (d-spacing of 4.43 Å) 7 . It has been reported that the amino acids glycine, alanine, serine and threonine constitute the crystalline regions in B. mori and common wild silks 7 . Peak broadening is a clear indication of nanocrystalline nature of these -sheet structures.…”

“…Silk fibres have more advantages like high strength, durability, lustre and other unique features compared to common cellulose and synthetic fibres. Since 1930, efforts have been made to produce protein fibres using various protein sources 7 . Raw silk consists of two proteins -sericin and fibroin.…”