by Green Plastics
Our recent news article about algae as a source for bioplastic has received a lot of attention. But there is something very important that it didn’t tell you:
You can make your own bioplastic from algae. And we will give you step-by-step instructions on how to do it.
It’s a fun little science project. You can do it in your kitchen, with stuff you buy at the grocery store. And you can see what “algae bioplastic” really looks and feels like.
First, a little background. You might not have known this, but when people talk about “seaweed” they are actually talking about a form of algae. That is what we are talking about in the context of bioplastics: red algae, also known as “red seaweed.” The specific chemical that we are interested in is agar, which appears in red seaweed in abundance. When you hear Cereplast and other companies talk about developing bioplastic made from seaweed, they really mean that they will be using the chemical agar, which is extracted from the seaweed.
Fortunately (or unfortunately?) this project won’t have you traipsing out to the ocean to collect seaweed. Agar is used as a food additive in confectionaries, desserts, beverages, icecream and health foods. It’s also used as a non-food additive in toothpaste, cosmetics, and adhesives. It’s not that difficult to get: if you can’t find it at the grocery store, you can Google “buy agar” and you get plenty of results there.
Before we get to the actual recipe for making your very own “algae plastic”, you should understand what role agar actually plays. Like all other plastics, bioplastics are composed of three basic parts: one or more polymers, one or more plasticizers, plus one or more additives. Roughly speaking: polymers give plastic its strength, plasticizers give it its bendable and mouldable qualities, and additives give it other properties (color, durability, etc). Agar is a biopolymer.
From the Green Plastics book:
Agar, either by itself or in blends with other biopolymers, appears to impart favorable properties to plastic sheets. In plastics containing agar and glycerol (a plasticizer), the effectiveness of the glycerol lasts longer, because the agar seems to slow down the increase in brittleness. Agar also seems to improve resistence to microwave radiation, and it improves clarity in sorbitol formulations. Agar is more expensive than starch, which limits its large-scale use.
Are you ready to try this? You basic procedure for making the bioplastic will be the same as described Brandon’s Remix video. The main difference will be in the actual ingredients and proportions. Here are some suggestions you can try. Each of the following combinations will produce slightly different plastics with different properties.
3.0 g (1 tsp) agar
240 ml (1 cup) of 1% glycerol solution
180 ml (3/4 cup) water
1.5 g (1/2 tsp) sorbitol
3.0 g (1 tsp) starch
300 ml (1 1/4 cup) water
0.75 g (1/2 tsp) agar
120 ml (1/2 cup) of 1% glycerol solution
2.25 g (3/4 cup) sorbitol
2.25 g (3/4 cup) gelatin
2.25 g (3/4 cup) agar
180 ml (3/4 cup) of 1% glycerol solution
240 ml (1 cup) water
The procedure is basically the same in every case. Mix all of the ingredients together in the amounts above, and stir. Keep mixing until there are no clumps and it is as dispersed as it’s gong to get. Then heat the mixture to 95 C or to when it starts to froth (whichever comes first). Stir the mixture while you are heating it, and once it is at the right temperature (or starts to froth), remove the heat and keep stirring. Scoop out excess froth with a spoon, and make sure there are no clumps. Carefully pour the mixture into a drying pan, and make sure to spread it out to let it dry.
How long it takes will depend on the temperature and humidity in the room, and it may take several days (depending on your formulation). You won’t be able to remove the plastic from the drying sheet easily until it is completely dry, so be patient! If your first batch turns out too sticky or slimy, you can try it again with slightly less plasticizer. Remember, the above recipes are just starting points…. have fun trying different proportions and combinations, and see what kinds of plastic it makes!
(For many more recipes like these, and a lot of good information about the background and science of bioplastics, get the Green Plastics book.)