Plastics are a group of materials that are made up of long chains of repeated molecules. There are lots of different types of plastics with different properties. The differences between plastics are caused by using different molecules in the long repeated chains.
To make the plastic Christmas Decorations the first thing that you need to do is measure out 250 ml of milk and then heat it in the microwave for about a minute so that it is hot but not boiling.
The next thing that we are going to do is add 4 teaspoons of vinegar and stir them together
Now you should see that the milk starts to clump together. This is because the acid in the vinegar starts to break down the proteins in the milk.
You are going to continue to stir this for a few minutes and then once the mixture has cooled, we are going to scoop out the white clumps (or curds) and put them onto the kitchen roll.
Use the kitchen roll to absorb any excess liquid and then you can knead what is left into a ball of dough. This is the plastic and you can add food colouring to it to colour it.
You can shape it either by hand or if you have some Christmas cookie cutters you can use them to make your Christmas decorations. When you are happy with your shapes make a hole in the top with a cocktail stick so they can be hung up and put them on some kitchen roll to dry. You will need to leave them for 2 days to dry out and then they will be ready to decorate your Christmas Tree!
You can make milk into plastic as milk contains protein molecules. When you heat it, and add vinegar (an acid), you can make the protein molecules unfold and reform into a long chain.
The video tutorial for this activity is available on the Surrey Libraries Facebook Page or the Surrey Libraries YouTube Channel