The study on structural properties and tensile strength of reared silkworm cocoon

Abstract Silkworm cocoon is a natural composite with laminated structure in which is made of silk fibers conglutinated by sericin. Recently, the identification of silkworm cocoon composite structure as a nonwoven complex structure and its properties are attracted by several researches. In this study, the structure and morphology of reared silkworm cocoon as well as its mechanical properties have been studied. Silkworm cocoon structural features, such as fiber diameter, porosity, fiber length, number of fiber intersection, the number of pores, and fiber orientation were evaluated for outermost and innermost layers in three sections using image processing method. Also the mechanical properties such as tensile strength, initial modulus, and toughness of silkworm cocoon in the three sections of cocoon head, middle, and tail were measured. The structural analysis of silkworm cocoon shows that the innermost layer has finer fibers with a lower density structure compared to the outermost layer. Fiber orientation in cocoon middle section is more than the head and tail sections. Also the results of mechanical properties of silkworm cocoon show that tensile strength, initial modulus, and toughness are significantly different in three sections of cocoon in which the cocoon middle section exhibits a higher tensile strength and initial modulus than the head and tail sections.