Practical 8
The Strength of Plant fibres
To determine the tensile strength of plant fibres.
Hypothesis:
The longer the plant fibre,the stronger the tensile strength
Tensile strength is the maximum pulling force that can be applied to a tissue before the
tissue breaks. The fibres are made of cellulose, which is a long chain polysaccharides, made
up of beta glucose molecules. Each molecule is inverted and held together by glycosidic
bonds. The fibres in plants are held together by lignin and pectin, which act similar to a glue.
When many of the fibres are held together by this glue they form microfibrils, which are
extracted through the process ‘retting’. To dissolve the glue, plants can either be water retted
or retting flax.This process causes the glue to loosen, allowing the fibres to be extracted.
Equipment :
● 2 clamp stands
● G clamps
● A set of weights
● Retted fibre
● Gloves
● Scalpel
● Goggles
● Tray
Variables:
● Dependent-the amount of mass added
● Independent- length of the fibre used
● Control- size of the weights ,width of the fibre
Risk Assessment;
➔ Probability/severity of risk: 1-Low, 2-Medium, 3-High/Likely
➔ Total Risk: 1, 2,3, 4, 6, 9
Risk Hazard Severity Probability Total Precaution taken
Risk
weight injuries to 1 2 2 Keep weights away from
body table edge
Fibres may 2 2 4 Wear goggles and gloves
irritate to prevent coming in
eyes contact with fibres
sharp injuries to 2 2 4 Handle with care, carry
objects e.g. body safely and securely
scalpel
The Strength of Plant fibres
To determine the tensile strength of plant fibres.
Hypothesis:
The longer the plant fibre,the stronger the tensile strength
Tensile strength is the maximum pulling force that can be applied to a tissue before the
tissue breaks. The fibres are made of cellulose, which is a long chain polysaccharides, made
up of beta glucose molecules. Each molecule is inverted and held together by glycosidic
bonds. The fibres in plants are held together by lignin and pectin, which act similar to a glue.
When many of the fibres are held together by this glue they form microfibrils, which are
extracted through the process ‘retting’. To dissolve the glue, plants can either be water retted
or retting flax.This process causes the glue to loosen, allowing the fibres to be extracted.
Equipment :
● 2 clamp stands
● G clamps
● A set of weights
● Retted fibre
● Gloves
● Scalpel
● Goggles
● Tray
Variables:
● Dependent-the amount of mass added
● Independent- length of the fibre used
● Control- size of the weights ,width of the fibre
Risk Assessment;
➔ Probability/severity of risk: 1-Low, 2-Medium, 3-High/Likely
➔ Total Risk: 1, 2,3, 4, 6, 9
Risk Hazard Severity Probability Total Precaution taken
Risk
weight injuries to 1 2 2 Keep weights away from
body table edge
Fibres may 2 2 4 Wear goggles and gloves
irritate to prevent coming in
eyes contact with fibres
sharp injuries to 2 2 4 Handle with care, carry
objects e.g. body safely and securely
scalpel
