PLA foam: a likely viable alternative to polystyrene

This article is about a material very similar to polystyrene but of plant origin: expanded PLA. PLA stands for polylactic acid and is a plastic of plant origin that is very well known especially in the world of 3D printing. Indeed, it is used in the manufacture of products through the use of 3D printers. The process to obtain PLA starts with the fermentation of lactic acid, which can occur naturally or synthetically. The difference between the two is very important because with the former the plastic obtained is easily compostable, like all organic products. The latter, on the other hand, is still compostable but requires specific temperature conditions.

There are several companies in the world that are pursuing the development of expanded PLA as a viable alternative to polystyrene. Unfortunately, there are many technical difficulties, and expanded PLA is still a prototype material. These difficulties include the expansion process of the PLA pellets (totally different to that of polystyrene) and mainly the synthesis of the expanded grains in the inner parts of the molded block. In appearance, expanded PLA is really very similar to polystyrene, even though at the same density it turns out to be much stiffer. This can be a nice advantage in its use as a material for making gadgets, certainly less so for packaging. The grain is particularly coarse and, again, this is a property that is still not well studied since it is not a problem in the most common use which is packaging. In the photo below, it is possible to clearly see the grain of expanded PLA.

To better study its use with our machines, we made some tests with Oranje: we realized the rose in the images below.

We experienced that the cutting speed needs to be lower with respect to that of extruded polystyrene. On the other hand, during cutting, there is a nice aroma of burnt sugar, certainly more flavorful than cut styrofoam. In this regard, many scientific articles about the emissions created by vaporization of PLA argue that it has a level of toxicity comparable to all other plastics (certainly less than acrylonitrile butadiene styrene). Just as you don’t judge a person by appearance, we draw the conclusion that you don’t judge toxicity by smell. The cut you get with the Oranje is sharp and very clean, provided some plastic filament is produced in the casting but easily removed by hand. We made a small project divided into several parts to try various colors. The black part of the exterior we painted with spray can while the leaves with brush. The most interesting thing is that we painted the rose petals with a regular solvent spray can. Well, yes! Unlike polystyrene which dissolves with any solvent, PLA absolutely isn’t. This feature might raise the antennae of most, aware of the great difficulties one has in finishing styrofoam due to the need to find all specific solvent-free products. So, we can affirm that our experiment yielded appreciable results, so expanded PLA is a very viable alternative to styrofoam.

You may ask, what is the problem then? Why don’t we all start using expanded PLA? The answer is purely economic. Expanded PLA currently costs 7 to 8 times more then styrofoam in bulk. It goes without saying that its use is not currently a plausible option for all professionals working with our machines and styrofoam. The thing that can hearten us is that it is not a cost related to the material itself but to the innovative production process and the poor economies of scale that manufacturers have, coupled with low demand from the market. We hope that our institutions will decide to either strengthen the styrofoam recycling supply chain or incentivize the use of expanded PLA. As PolyShaper, we encourage the use of this material, in an optics of safeguarding the environment as most as possible.