Store cupboard science for the festive season – bioplastic decorations!

Bioplastic Christmas Ornaments

With our trees and decs going up even earlier this year why not have a go at making your own. You’ll be amazed at what we used – jelly (well gelatine actually, but close!).

This experiment involves heat so an adult needs to help.

You’ll need – 75ml water, 2-3 drops of food colouring, three gelatine powder packets and a mould (such as a snowman ice cube tray).

Mix the water and food colouring. Add in the gelatine and mix together over a medium heat until until completely mixed. Once mixed in stir gently as we don’t want to create a foamy mix. As it starts to steam and becomes thick remove from the heat.  If there is a foam layer scrape off with a spoon as you don’t want to have foamy bubbles in your plastic! Pour into a mould (we used some ice cube trays) – it will be hot so get an adult to help you.  Leave to cool and firm in the mould for a few days. They feel rubbery at first but harden off over the days.

Once fully hard take out and glue a ribbon to the top of your ornament for hanging on the tree.

What’s happened and why?

You’ve created a form of bioplastics. These are made from food rather than oil, and are seen to be environmentally friendly. In the summer we used milk proteins to make plastic (link to experiment) and this time we used gelatine.

Gelatine is created by breaking down collagen which is found in all animals where it binds cells together.  Collagen is a long chain of amino acids

Gelatine has long chains of hundreds of amino acids. At room temperature its solid, but as it heats up the bonds between these long chains loosen allowing them to slide apart and stretch.  Gelatine has a strong affinity for water and the hydrogen atoms that are attached to the side of the chains can bond with water molecules.  During the heating and mixing of our mix we are weakening the chains and as we cool the mixture the hydrogen atoms form connections with the water molecules and form a hydrogen bond. Our mix contains a lot of gelatin compared to water.  All the water molecules bond with the hydrogen molecules and the amino acid chains start to bond with itself, trapping water molecules inside its structure and so all the water molecules are used up forming a hard plastic. It’s like cross-linking paperclips together – they can no long move freely and form a solid structure.

For more information on this experiment head over to the Steam Powered Family website. This will take you to another website.