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Self Healing Plastic

Leave a reply Jonny Hankins

One of the problems with plastic is that it is very difficult to repair once damaged. When there is a hole in your plastic bucket you cannot generally mend it. But researchers in Spain have developed the world’s first self healing plastic.

Cutting the self healing plastic

Cutting the self healing plastic

Researchers at the CIDETEC Centre for Electrochemical Technologies in San Sebastian, Spain have developed a plastic that once broken can heal itself. All the user has to do is put the pieces together and leave it at room temperature for a couple of hours, and the material kind of re-molds itself. The repair is said to be 97% perfect within a couple of hours, and perfect 2 days later, and a Youtube video demonstrating the strength of the repair is really quite incredible.

Plastics are made up of polymers, a long chain of molecules that are connected through chemical bonds. Natural polymers are everywhere. In nature, many polymers heal themselves when broken or sliced. Think of your skin when you have a small cut — as the two sides of the cut bind back together, you’re witnessing a self-healing polymer in action.

Synthetic polymers are just as common. Scientists started creating nylon and synthetic rubber to make up for the shortage of silk and rubber during World War II. PVC, polyester and many forms of plastic soon followed.

Putting the pieces together

Putting the pieces together

The Spanish have developed the first human-made self-healing polymer to function without a catalyst, they report in the Sept. 13 issue of the journal Materials Horizon. There are in fact other self healing plastics, but they require a catalyst to start the process (ultra violet light for example). Readers might know about self scratch repair paint, as advertised on TV. This paint is made from prawn shells, a fine example of a natural self healing material that uses the sun as catalyst.

The article states that “The idea behind this is to reconnect the chemical crosslinks which are broken when a material fractures, restoring the integrity of the material. This is expected to provide polymers with enhanced lifetime and resistance to fatigue”.

Testing the repair

Testing the repair

The researchers say this breakthrough will allow them to create stronger sealants, paints, adhesives and more. This could eventually lead to self-repairing pipes, bicycle tires and toys, among a million other possibilities.

Sounds great to me, and the less plastic we throw away the better.

Turning Human Waste into Plastic

2 Replies Jonny Hankins

One of the unsung heroes and villains of modern life is human waste, or poo as we like to call it. It is like death and taxes in that well known phrase about certainty, there is an awful lot of it around, and it is full or carbon.

A few years ago there was uproar when we discovered that farmers were using human waste to make their plants grow faster, a practice that like many of life’s more unsavoury issues has remained largely out of the public gaze for years. But what do we do with all of this waste? We can just pump it out into the sea, or dump it in landfill sites as is common in the USA, although these don’t really seem like great solutions to me. Good news is on the horizon though, a company in California has started to use it to make plastic, taking some out of the dumping category and making use of the carbon.

Admittedly we have the old gag reflex again. A plate of carrots grown with the aid of human waste to go with your minced beef with horse trace pie with a plastic bottle made out of human sewage full of fresh, crystal clear mountain water to wash it all down. But just think about the potential.

Waste Not.

Make Use of Human Waste

Plastic can be produced using human waste, bottles can be made from it, and it is biodegradable, so why not? This BBC video tells the story of an experimental bio-plastics lab called Micromidas, where this process is being experimented and researched, and where human waste is already being turned into plastic.

The process involves making a kind of nutrient soup from the waste to which bacteria is added. They produce something called PHA, a type of polyester. They feed on the waste and take up the carbon and turn it into this form of plastic. Then the plastic containing parts are separated and cleaned.

The material is then dried, the plastic extracted and made into pellets. It can then be used to make practically anything that we currently make using fossil fuel based plastic. There is after all no shortage of raw materials, so proponents hope to replace the old fossil fuel production with the new.

The process is very much in experimental stage, but the researchers hope to be able to produce on mass within the next 2 to 3 years, bringing the price down so that it can compete in a global market. Good for everyone, and the environment.

Just as a slightly less obnoxious adjunct I would like to add that Micromidas are also setting up a lab that is working on turning cardboard into Paraxylene, a chemical once more used to make plastic bottles, again in the hope of getting into and cutting out the fossil fuel market (usually Paraxylene comes from oil). Read this report about their work.