Bioplastic
Making a plastic from potato starch – extracting starch
In this activity you are going to extract starch from potatoes. This starch can be used to make a plastic. A similar process is used in industry to extract starch, which is then used in a number of products, including food and packaging.
You will need: q q q q q q
Approx 100 g clean (not muddy) potatoes Grater Tea strainer Distilled water Pestle and mortar 100 cm3 measuring cylinder.
What to do q q
q
q q
Grate about 100 g potato. The potato does not need to be peeled, but it should be clean. Put the potato into the mortar and add about 100 cm3 distilled water. Grind the potato carefully. Pour the liquid off through the tea strainer into the beaker, leaving the potato behind in the mortar. Add 100 cm3 water, grind and strain twice more. Leave the mixture to settle in the beaker for 5 minutes. Decant the water from the beaker, leaving behind the white starch which should have settled in the bottom. Add about 100 g distilled water to the starch and stir gently. Leave to settle again and then decant the water, leaving the starch behind.
You can now use the starch to make a plastic film.
Making a plastic from potato starch – page 1 of 7, Index 3.1.7
PHO
TO C
P
OP
Y
Making a plastic from potato starch – making the plastic
In this activity you will make a plastic film from potato starch and test its properties. Potato starch is a polymer made of long chains of glucose units joined together. It actually contains two polymers: q q
Amylose, which is a straight chain of glucose units Amylopectin, which is a branched polymer, also made of glucose units.
The amylopectin prevents the starch from becoming plastic-like. You will use hydrochloric acid to break down the amylopectin and change the stucture and properties of the polymer. You will make two different batches of the potato plastic. In one you will add some propan1,2,3-triol (also known as glycerol), which will
In this activity you are going to extract starch from potatoes. This starch can be used to make a plastic. A similar process is used in industry to extract starch, which is then used in a number of products, including food and packaging.
You will need: q q q q q q
Approx 100 g clean (not muddy) potatoes Grater Tea strainer Distilled water Pestle and mortar 100 cm3 measuring cylinder.
What to do q q
q
q q
Grate about 100 g potato. The potato does not need to be peeled, but it should be clean. Put the potato into the mortar and add about 100 cm3 distilled water. Grind the potato carefully. Pour the liquid off through the tea strainer into the beaker, leaving the potato behind in the mortar. Add 100 cm3 water, grind and strain twice more. Leave the mixture to settle in the beaker for 5 minutes. Decant the water from the beaker, leaving behind the white starch which should have settled in the bottom. Add about 100 g distilled water to the starch and stir gently. Leave to settle again and then decant the water, leaving the starch behind.
You can now use the starch to make a plastic film.
Making a plastic from potato starch – page 1 of 7, Index 3.1.7
PHO
TO C
P
OP
Y
Making a plastic from potato starch – making the plastic
In this activity you will make a plastic film from potato starch and test its properties. Potato starch is a polymer made of long chains of glucose units joined together. It actually contains two polymers: q q
Amylose, which is a straight chain of glucose units Amylopectin, which is a branched polymer, also made of glucose units.
The amylopectin prevents the starch from becoming plastic-like. You will use hydrochloric acid to break down the amylopectin and change the stucture and properties of the polymer. You will make two different batches of the potato plastic. In one you will add some propan1,2,3-triol (also known as glycerol), which will