According to European Bioplastics, the global production of bioplastics is around 2.2 million tons (data from 2022), which represents less than one percent of the over 390 million tons of plastic produced annually (Plastics Europe for 2021, Plastics – The Facts, 2022). Within these 2.2 million tons, approximately one million correspond to non-biodegradable but bio-based plastics, mainly polyethylene (PE), polyamides (PA), and poly(trimethylene terephthalate) (PTT). (These are plastics that don’t differ from conventional ones in anything except the raw materials they are made from.) Also included are slightly less than 100,000 tons of poly(butylene adipate-co-terephthalate), PBAT, a biodegradable but not bio-based polymer. PBAT is an aromatic polyester produced from petrochemical-derived 1,4-butanediol, adipic acid, and dimethyl terephthalate. Other similar polymers, biodegradable but not bio-based and produced in smaller quantities, are polycaprolactone and poly(butylene succinate).
As indicated in a previous post, the most relevant bioplastics are those at the same time bio-based and biodegradable (meaning compostable), which have been referred to as BioCom. This category excludes biodegradable polymers that are not bio-based (PBAT) and those bio-based but not biodegradable (PE, PA, PTT). The global annual production of bioplastics mentioned earlier includes 80,000 tons of regenerated cellulose films (there are other types of industrial cellulose) and 400,000 tons of thermoplastic starch (TPS) (Source: European Bioplastics). The rest of the BioCom polymers amount to 460,000 tons of polylactic acid, PLA, and about 90,000 tons of polyhydroxyalkanoate, PHA. There are other emerging polymers expected to play a significant role in the future, such as poly(ethylene furanoate), but for now, BioCom production is concentrated on the four types mentioned earlier: cellulose, TPS, and the aliphatic polyesters PHA and PLA.
It is still a relatively small production, although projections anticipate sustained growth in the near future. The main commercial bioplastic is PLA, produced by the polymerization of lactic acid or its esters, which in turn can be biotechnologically obtained from raw materials like corn starch or sugarcane. TPS is a blend of two polymers, amylose, and amylopectin, both consisting of a sequence of glucose units. When mixed with water and plasticizers such as glycerol or sorbitol, it becomes a thermoplastic material. Despite its easy obtention (from cereals, legumes, or potatoes) and numerous potential uses, the industrial use of TPS is hindered by its high hydrophilicity (due to the presence of hydroxyl groups) and limited mechanical properties. For this reason, it’s used in blends with various fillers and other polymers, particularly with biodegradable polyesters like PLA or PBAT.
The potential uses of bioplastics are quite extensive, although the majority of current production is concentrated in agricultural applications, particularly in the production of plastic film for mulching, as well as the manufacturing of various types of bags and packaging materials. Another well-established application is the manufacture of biodegradable consumer products that range from tableware (cutlery, cups, and the like) to parts of electronic equipment such as circuit boards or computer casings. Still under development there are various biomedical applications, such as the production of absorbable staples or sutures, and controlled-release capsules (PolyActive by Afinitica). Finally, an area with significant developmental potential is the automotive industry, for uses such as coatings, carpets, and other interior vehicle components.
Agricultural mulching is currently the primary application of bioplastics. The first use of plastic for mulching (and also as greenhouse covering) took place in the 1950s in the United States, following the work of Professor Emery Myers Emmert from the University of Kentucky, who laid the foundation for plasticulture. Mulches cover the soil around plants, retain moisture, regulate soil temperature, and inhibit the growth of unwanted plants (weeds in agricultural terms), thereby increasing productivity. Over time, films of varying thickness have been developed for different crops, with different colours for different climates or target soil temperatures. The installation and management methods for mulch films have been improved, but the traditional (and cost-effective) polyethylene film has the drawback that it is difficult (generally impossible) to completely recover after harvest. This is because it easily tears off due to its thinness, which can be as fine as 60 microns. Additionally, its use is incompatible with certain mechanical harvesting operations.
Biodegradable mulches are products that disintegrate in the soil at the end of the cultivation period, thereby eliminating the need to remove and recycle mulches made from conventional plastics. Their use not only avoids the costs of collection and waste treatment (complex due to the mixture of soil and crop residues), but also limits soil pollution with plastic fragments. Biodegradable mulches must comply with the EN 17033 standard – Plastics – Biodegradable mulch films for use in agriculture and horticulture, which is complemented by requirements for conventional mulches that need to be recovered after use (EN 13655). Commercial biodegradable mulches are made of biodegradable polymers depending on the manufacturer and may contain TPS, PLA, and PBAT, along with plasticizers, additives such as UV filters, antioxidants, colorants, and various fillers. This category includes BASF’s Ecovio, a blend based on Ecoflex (PBAT) and PLA, and mulches based on Novamont’s Mater-Bi, a material whose most common version contains TPS and PBAT (though Mater-Bi encompasses other formulations as well). These materials currently have a small market share, accounting for 5% of the total mulch market, which in Europe amounts to over 100,000 tons, but their use is expected to follow a growing trend, with global market growth estimated at just under 10% annually until 2030.
Biodegradable bags, packaging, and other materials are made from the same biopolymers mentioned before that can combine with other easily degradable natural substances such as paper, cardboard, and natural fibers. Generally, this type of product only degrades properly in industrial composting facilities, as defined by the harmonized standard EN 13432, which sets specific criteria for packaging to be composted. Only lightweight bags can be compostable in home composting facilities if they meet the recent EN 17427 standard. The composition of these lightweight bags also involves a combination of the aforementioned biopolymers: TPS, PBAT, PLA, and various additives. Finally, biopolymers are used to create a range of items including compostable cutlery, plates, and cups (all subject to EU Directive 2019/904 on the reduction of the impact of certain plastic products on the environment).
It is important to emphasize that not all bioplastics are biodegradable, and those that are biodegradable can generally degrade only in industrial composting facilities. A bioplastic, even if it is biodegradable and not just bio-based, can persist in the environment for years or decades if improperly discarded, so its use should not be trivialized. Lastly, it is important for consumers to be able to distinguish compostable bioplastics (which can be composted along with organic waste) from conventional plastics (among which only packaging is typically recycled), in order to avoid mixing incompatible materials that hinder proper recycling.
Science, Plastic and Environment 