My journey into the world of bioplastics has been a mad experience through an alien landscape. I went to the grocery store and I got me some cornstarch, thermometer, food colouring (ALL COLOURS BECAUSE I’M ~*PRIMARY*~), milk, vinegar… and went to the local pharmacy to get me some glycerin.
I still haven’t had time to do casein (milk) bioplastic yet so I decided to stick to corn for now. I’m really interested in chitin, algae, tapioca, potato, gelatine, sunflower seed, soya bean proteins, yam, banana skin, etc or more or even combining different polymers with fibres like flax and hemp. Bioplastics Party, anyone…?
Experiment 1: using the Instructables base ingredients and recipe.
- 1/2 cup cornstarch
- 1/2 cup water
- 1 tsp canola oil
- 3 drops of blue food colouring
Experiment 2: using Instructables base ingredients and recipe but adding MORE water to make more pliable.
- 1/2 cup cornstarch
- 1 cup water
- 1 teaspoon canola oil
- 3 drops yellow food colouring
+ HEART: I had some extra left of experiment 2 after I poured the mixture into the aluminium foil cupcake moulds so I decided to add a drop of blue food colouring to a single heart-shaped mould and let it mix by itself with the yellow mixture.
Then I reached a plateau because I was like, wait.. I don’t have a microwave. I considered this for a bit and then decided to just bake my mixture for an undetermined amount of time. It was 1:09 PM. I baked the mixture (all of the above together) until 1:25, a total of 16 minutes. Then I took it out and let it cool down.
Experiment 3: Using Greenplasticsnet’s recipe and ingredients
- 1 tbsp cornstarch
- 4 tbsp water
- 1 tsp glycerin
- 2 drops of yellow food colouring
This recipe asked for the mixture to be heated on the stove. However, it did not specify what temperature, how long, when I should start the heat so I mixed all of the ingredients before turning on the heat and continuing to stir until it looked kind of kneadable and jelly-like. I tried with no food colouring and then a second batch WITH food colouring (red and yellow). I guess the second batch turned out slightly more malleable and clay-like probably because I still had remnants of the first batch at the bottom of the pot (…because I was lazy…)
- Oven-baked cornstarch bioplastic is a lot more gelatin/jelly-like than the stove-cooked bioplastic. The latter is a lot more malleable like hot, soft clay when fresh.
- Both CRACK and shrivel (shrink) when dried. This is problematic… I need to figure out how best to tackle this problem. Would refrigerating help? What about pouring resin over it before it dries?
- I’ve read that the pliability of the bioplastic depends not only on how much cornstarch/water you put in but also the amount of glycerin. If you put in a lot of glycerin, there is the likelihood that the plastic will never dry, which is interesting.
- How to stop the bioplastic from biodegrading as much as possible even if it endures heat (for example, an LED light…?)
- The corners of the oven-baked bioplastic are interesting; they’re translucent/transparent and very plastic like.
- I’m not sure the canola oil helped with anything except to form these interesting oil spot textures on the surface of the oven-baked bioplastic.
And that’s the end of this episode of Fun with Bioplastics. Tune in next time for further
kid’s serious lab experiments.