Title

Mechanical properties of black widow (Latrodectus hesperus) eggcase silk.

Poster Number

11

Format

Poster Presentation

Abstract/Artist Statement

Spider silks with load-bearing function have been studied extensively, but non-load bearing silks, such as egg case silk have not. This is the first study in mechanical properties of egg case silk. Silk :from the egg cases ofblack widow spiders (Latrodectus hesperus) was stretched to breaking in order to examine its stress-strain relationship. Spider silk was attached to the wires on both 1 force transducer and level ann of the tensiometer. Then, the tensiometer broke the silk by moving the lever ann slowly away from the force transducer. The recorded force and 1 displacement were used to investigate both strain and stress properties of eggcase silk. Next, the silk's diameter was examined with the aid of a compound light microscope, which is essential in analyzing the stress property. The stress-strain curve shows an initial stiff; linear region followed' by a yield point and then a significantly less stiff, linear region. Egg case silk broke. around 60% strain with an average strength of600 GPa. The mean ofthe yield strain was 4.0% while its average yield stress was 360GPa The pre-yield stiffness average was 10.9GPa and the post-yield stiffness has a mean of 0.53GPa. The average diameter of the thread was 3.6 JJ.lll. The stress-strain curve of Latrodectus hesperus eggcase silk was discovered to show · resemblance to the curve from the dragline silk of the same species. However, due to the differences in functions, eggcase silk's mechanical properties are distinctively different than any . other known spider silk. (NSF DBI-9996072).

Location

DeRosa University Center

Start Date

1-5-2001 9:00 AM

End Date

1-5-2001 5:00 PM

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May 1st, 9:00 AM May 1st, 5:00 PM

Mechanical properties of black widow (Latrodectus hesperus) eggcase silk.

DeRosa University Center

Spider silks with load-bearing function have been studied extensively, but non-load bearing silks, such as egg case silk have not. This is the first study in mechanical properties of egg case silk. Silk :from the egg cases ofblack widow spiders (Latrodectus hesperus) was stretched to breaking in order to examine its stress-strain relationship. Spider silk was attached to the wires on both 1 force transducer and level ann of the tensiometer. Then, the tensiometer broke the silk by moving the lever ann slowly away from the force transducer. The recorded force and 1 displacement were used to investigate both strain and stress properties of eggcase silk. Next, the silk's diameter was examined with the aid of a compound light microscope, which is essential in analyzing the stress property. The stress-strain curve shows an initial stiff; linear region followed' by a yield point and then a significantly less stiff, linear region. Egg case silk broke. around 60% strain with an average strength of600 GPa. The mean ofthe yield strain was 4.0% while its average yield stress was 360GPa The pre-yield stiffness average was 10.9GPa and the post-yield stiffness has a mean of 0.53GPa. The average diameter of the thread was 3.6 JJ.lll. The stress-strain curve of Latrodectus hesperus eggcase silk was discovered to show · resemblance to the curve from the dragline silk of the same species. However, due to the differences in functions, eggcase silk's mechanical properties are distinctively different than any . other known spider silk. (NSF DBI-9996072).