Biodegradable polymers. Advantages and disadvantages compared to conventional polymers.
A biodegradable polymer is one that can be completely broken down by the environment, thereby reducing the environmental impact of these materials. Therefore, according to this definition, when a biodegradable plastic container is discarded at the end of its useful life, its molecular structure—and thus its physical and chemical properties—begins to change due to the influence of environmental agents.
Thus, the polymer is transformed into simple substances or minor components such as water, carbon dioxide, and biomass, which are ultimately assimilated by the environment.
Based on their origin, biodegradable polymers can be classified as follows:
– Naturally occurring polymers: These are derived from marine animals, plants, and even bacteria. Examples of this type of polymer include starch, cellulose, polysaccharides, proteins, and polyhydroxyalkanoates.
– Modified natural polymers: such as cellulose acetate
– Synthetic polymers: The most important ones are polylactic acid and polycaprolactone, both because they are easy to produce and process, and because they are versatile and relatively inexpensive to produce.
– Combinations of the above: these are materials composed of a natural polymer and a synthetic polymer. For example, a mixture of starch and polystyrene. These materials are very interesting because their production costs are lower, they can exhibit remarkable mechanical properties, and the rate of polymer degradation can be controlled.
These materials offer a number of clear advantages over traditional plastics. The first of these is that they eliminate the need to rely on petroleum as a raw material for their production.
The second advantage they offer is that they can degrade completely within a relatively short period of time (compared to typical plastics), and the byproducts of their degradation are generally water, carbon dioxide, and biomass.
Finally, these biomaterials have opened the door to medical research, as many of the advances made in medicine have been made possible by the discovery of certain biodegradable polymers that are compatible with the human body and, after fulfilling their function, break down without the need for surgical intervention.
However, biodegradable polymers also have disadvantages compared to traditional polymers.
The biggest drawback is that, in general, the production cost of a biodegradable polymer is considerably higher than that of a petroleum-based plastic.
Furthermore, in many cases, the mechanical properties of biodegradable polymers are inferior to those of typical plastics, as they have lower physical strength.