core practical 8: measuring tensile strength of plant

what is tensile strenght

The tensile strength of a fibre refers to the maximum load it can carry before breaking

method

1. The fibre should be hanging from a clamp stand

2. Attach a weight on the other end of the plant fibre

3. gradual addition of mass until the fibre breaks

4. Record the mass at which the fibre broke

5. To increase the accuracy of your results, repeat experiment/ measurements and calculate mean/SD

   • It is important to ensure that the fibres are all of the same length and that all other variables are kept constant eg humidity, temp

how to determine the cross-sectional area of a fibre

• a (transverse) section/layer/slice of the fibre is cut (1)

• ensure section is flat (1)

• graticule calibrated (with stage micrometer) (1)

• diameter measured/found using eyepiece graticule

• and converted to measurement with calibration data (1)

• area calculated using πr2 (1)

why fibre diameter measured

• fibre {diameter / radius} is needed to calculate (cross sectional) area (1)

• (cross sectional) area is needed to calculate tensile strength / strength of fibre (1)

• diameter will affect {tensile strength / strength of fibres} (1)