Morphology, molecular conformation and moisture regain of cocoons of different silkworm varieties

Silk has attracted the attention of numerous research groups because of its unique properties as a biomedical material. Recently, studies on the biomedical application of silk cocoon, such as membranes for guided bone regeneration, have been conducted. As a preliminary study on silkworm cocoons, the morphological structure and crystallinity of cocoon of nine silkworm varieties with different sides are examined in this study. The morphological structure of the silkworm cocoon is shown to be dependent on silkworm variety and the cocoon layer (i.e. outside or inside). It is also shown that the silk filaments of the out layer are more bent and twisted compared to those of the inner layer. Furthermore, the crystallinity of the outer surface of all silkworm cocoons is found to be higher than that of the inner surface, regardless of the silkworm variety. Lastly, it is shown that the crystallinity index of the cocoon depends on the silkworm variety, implying that the structure of the cocoon varies with silkworm variety.