In Chile, the use of fossil plastics is intensive and its recycling rate is low. Therefore, it is important to develop sustainable solutions that allow recycling of traditional plastics or replacing them with biobased thermoplastic materials.
The transition from the “age of oil” to the “age of sustainability” is an urgent need from the point of view of the environment, the economy and, of course, society. There are fossil materials, highly demanded and used during the twentieth century, which are dangerous and polluting. In addition, they frequently have a negative ecological footprint, which has an impact on the earth, the air and the oceans. What is the alternative?
The Technological Development Unit, UDT, of the Universidad de Concepcion, has been working for several years on different solutions to reduce the impact of plastics. The efforts are mainly focused on two lines of action: create new formulations for biodegradable/compostable plastics and develop recycling alternatives for conventional plastics.
Research related to biodegradable/compostable plastics is old worldwide. Álvaro Maldonado, head of the Biomaterials Department of UDT, points out that “one of our priority lines is to obtain formulations of biodegradable/compostable plastics based on polylactic acid (PLA), thermoplastic starch and PBAT, to which we add organic fillers such as algae and wood particles, reinforcements such as cellulose fibers and microfibrils, and different types of compatibilizing additives”.
These bioplastics come from renewable sources and degrade under composting conditions, at a certain temperature, humidity and in the presence of microorganisms in an average of 180 days, leaving CO2, water and biomass as remnants. The obstacle to massively use these raw materials is their high price, which is still at least twice that of conventional plastics.
However, cost is only one of the factors that influence the penetration of bioplastics in the market. Another challenge is technical, since these materials are required to have the same characteristics and performance as traditional plastics, in terms of their mechanical properties, fluidity and transparency, among others.
UDT has positive experiences in the development of bioplastics and their transformation into new products demanded by the market. “One of our main lines of work are the containers and packaging for fruit exports. Clamshell containers for berries are widely used in supermarkets in the country and abroad. In this context, UDT is developing a container with the same features that conventional PET plastic offers, but using PLA and different additives, matching the characteristics of transparency, softening temperature, compressive strength and stacking. The difference is that it is a compostable material, which adds value as a material for blueberry packaging”, says Maldonado.
There are several technologies available for the recycling of plastics; the most used in Chile is the mechanical type, typically of PET plastics, the material with which disposable bottles are manufactured. These processes have limitations, because the plastic must be clean and one type only, so that the material maintains its good quality characteristics. Therefore, mechanical recycling only reaches 8% of the total plastic waste in the country.
“In Europe, huge boilers are fed, in which plastic is incinerated to obtain energy. However, it is an alternative that requires high investment and is increasingly questioned from an environmental point of view, so its implementation in Chile cannot be expected. In UDT we are developing a chemical recycling of the pyrolysis type. It is a thermochemical process in the absence of oxygen, in which plastic degrades, generating solid, liquid and gaseous products”, explains Dr. Alex Berg, Executive Director of UDT.
Among its advantages is that it can process mixtures of plastics and, by refining the resulting liquids and solids, obtain an industrial diesel-type fuel and paraffinic waxes that can have different uses: as a water repellent agent on wooden panels and cartons; rheological modifiers in the plastics industry; and phase change materials to store thermal energy captured during daylight hours (for example, by means of solar collectors) and release it when the temperature drops in hot water applications and home heating systems.