title: Intrinsic tensile properties of cocoon silk fibres can be estimated by removing flaws through repeated tensile tests.
abstract: Silk fibres from silkworm cocoons have lower strength than spider silk and have received less attention as a source of high-performance fibres. In this work, we have used an innovative procedure to eliminate the flaws gradually of a single fibre specimen by retesting the unbroken portion of the fibre, after each fracture test. This was done multiple times so that the final test may provide the intrinsic fibre strength. During each retest, the fibre specimen began to yield once the failure load of the preceding test was exceeded. For each fibre specimen, a composite curve was constructed from multiple tests. The composite curves and analysis show that strengths of mass-produced Muga and Eri cocoon silk fibres increased from 446 to 618 MPa and from 337 to 452 MPa, respectively. Similarly, their toughness increased from 84 to 136 MJ m(-3) and from 61 to 104 MJ m(-3), respectively. Composite plots produced significantly less inter-specimen variations compared to values from single tests. The fibres with reduced flaws as a result of retests in the tested section have a tensile strength and toughness comparable to naturally spun dragline spider silk with a reported strength of 574 MPa and toughness of 91-158 MJ m(-3), which is used as a benchmark for developing high-performance fibres. This retesting approach is likely to provide useful insights into discrete flaw distributions and intrinsic mechanical properties of other fatigue-resistant materials.
authors.affiliation: Australian Future Fibres Research and Innovation Centre, Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216, Australia.
authors.forename: Rangam
authors.initials: R
authors.lastname: Rajkhowa
authors.affiliation: CSIRO Manufacturing Flagship, Geelong Technology Precinct, Deakin University, Geelong, VIC 3216, Australia.
authors.forename: Jasjeet
authors.initials: J
authors.lastname: Kaur
authors.affiliation: Australian Future Fibres Research and Innovation Centre, Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216, Australia School of Textile Science and Engineering, Wuhan Textile University, Wuhan, People's Republic of China.
authors.forename: Xungai
authors.initials: X
authors.lastname: Wang
authors.affiliation: Australian Pulp and Paper Institute, Department of Chemical Engineering, Monash University, Melbourne, Australia warren.batchelor@monash.edu.
authors.forename: Warren
authors.identifier: http://orcid.org/0000-0001-6880-7765
authors.initials: W
authors.lastname: Batchelor
mesh_terms: D000818:Animals; D012831:Bombyx; D047011:Silk / Q000737:chemistry*; D013112:Spiders; D013314:Stress, Mechanical; D016474:Weight-Bearing
chemical_list: D047011:Silk
keywords: fatigue resistance; flaws; retest; silk; tensile properties