Bioplastics

 

bioplastic ingredients 3 lo res

During my recent mind mapping sessions in the studio I was reminded of some experimentation I completed about a year ago on bioplastics. I didn’t delve too deeply into the subject at the time but did try out a few recipes.

The reason I started thinking about bioplastics is that I am conscious for this project that I will be creating works of art that will be installed in living trees. That these trees are part of a cycle of life and decay, constantly changing and adapting to their surroundings, is something that I would like to engage with to a greater or lesser extent in my choice of what materials to use in creating the works of art.

In an ideal world one wouldn’t install man made plastic, perspex or lycra based fabrics in the trees but these are the materials I commonly use in my practice because of their vibrance of colour and glossy qualities. I am sure some of the Bioplastic options that I investigate will lead me to creating some interesting pieces for this project but I still think that the qualities of my core materials will be necessary to fulfill the artistic goals of the project.

With this in mind I have decided to explore the world of bioplastics again but in a more in depth way. After visiting the really informative site called green-plastics.net I got a few recipes to start with and set off on an unusual shopping spree. One of the hardest things was to try and find some of the ingredients they mentioned. Instead of Agar powder I ended up with dried Agar. On the plus side I found red and green coloured dried Agar options as well as the clear one. I thought I had the glycerol/ glycerine situation under control when I bought a little bottle by Dr. Otker (the only brand available in any shop I tried) but despite an internet search I couldn’t figure out what percentage glycerine was in the mixture. Currently I am assuming that it 100% as is seems quite viscous but if this isn’t the case then I am in the dark regarding how much to use. It might end up being a bit of a case of trial and error. The next dilemma was the common one of Corn starch v’s Corn flour. Most internet searches say that they are both the same. Where corn flour is readily available in most stores corn starch is much harder to find. In actual fact I have been told that corn starch is more glutenous and the resultant plastic is more transparent than the corn starch, which is whiter. So I eventually found some corn starch in my small local Asian store (where I also found the Agar). Finally some recepies mention sorbitol, which is a type of sugar. After visiting a few supermarkets and health food stores I came away empty handed. It is available to order from home brew websites and I will endeavor to find some locally in the next week or so. In the meantime I will try the recipes where I have the ‘correct’ ingredients.

bioplastic ingredients lo res

On the plus side the selection of ingredients that I did manage to acquire did go together to make a lovely colourful image – see above.

At this point I think it’s important to know that 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 moldable qualities, and additives give it other properties (color, durability, etc). This information helps when the recipes online get a little complicated. It also helps when troubleshooting if the results seem too sticky (less plasticiser) or too brittle (more Plasticiser).

The three types of bioplastics that I will look at are the Starch-based, Gelatin-based and Agar-based plastics. Starch, Gelatin and Agar are all biopolymers. Most of the recipes I plan to try will use glycerine/ glycerol for the plasticiser.

Starch-based plastic:

Corn starch is the starch derived from the corn (maize) grain or wheat. The starch is obtained from the endosperm of the kernel. Corn starch is a popular food ingredient used in thickening sauces or soups, and is used in making corn syrup and other sugars.

Gelatin-based plastic:

Gelatin or gelatin is a translucent, colorless, brittle, flavorless food derived from collagen obtained from various animal body parts. It is commonly used as a gelling agent in food, pharmaceutical drugs, vitamin capsules, photography and cosmetic manufacturing. It is found in most jelly candy, as well as other products such as marshmallows, gelatin desserts, and some ice creams, dips and yogurts. Gelatin for recipe use comes in the form of sheets, granules, or powder. Instant types can be added to the food as they are; others need to be soaked in water beforehand.

Gelatin is actually easier to work with than starch and will produce some nice, strong pieces of solid plastic.

Agar-based plastic:

You can make your own bioplastic from algae. The specific chemical that we are interested in is agar, which appears in red seaweed in abundance. Agar is used as a food additive in confectionaries, desserts, beverages, ice cream and health foods. It’s also used as a non-food additive in toothpaste, cosmetics, and adhesives.

There are numerous combinations and a huge range of recipes available online that one can try. For examples each of the following combinations will produce slightly different plastics with different properties. The only way to find out how they all look, perform and last over time is to really get stuck into following the recipes and see what excites me!!

I will post some of the resulting images in a later post.

Agar Only

3 g (1 tsp) agar

240 ml (1 cup) of 1% glycerol solution
180 ml (3/4 cup) water

Agar-Starch Blend

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

Gelatin-Agar Blend

 

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

Of Interest:

Anyone interested in this subject might like to purchase the following book by E.S. Stevens. Green Plastics, an Introduction to the New Science of Biodegradable Plastics.

The book offers a wide variety of recipes and step-by-step instructions on making bioplastics with different properties, ranging from hard inflexible plastics to thin flexible sheets and laminates. In addition, the book carefully explains the theory behind bioplastics, with in-depth discussions of chemistry concepts as well as environmental concepts related to biodegradability and renewability.

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