Bioplastic

Bioplastics(or bio-based plastics) are plastic materials produced from renewable biomass sources rather than petrochemical sources. This definition distinguishes it from biodegradable plastics, which are plastics that degrade by the natural action of microorganisms such as algae or bacteria. In the context of bioeconomy and the circular economy, bioplastics remain topical.

The four main classes of bioplastics can be described as such:

• Natural Biopolymers: bioplastics processed from biopolymers with added plasticizers or stabilizers, such as polysaccharides (e.g., corn starch or rice starch, cellulose, chitosan, and alginate) and proteins (e.g., soy protein, gluten, and gelatin) or some forms of lipids (e.g., paraffin, lignin, and acetin)
• Chemical Synthesis: bioplastics chemically synthesized from sugar derivatives (e.g., lactic acid) and lipids (such as vegetable fats and oils) from either plants or animals
• Microbial synthesis: bioplastics formed from fermentation of sugars or lipids or biotechnological production in microorganisms or genetically modified plants (e.g., polyhydroxyalkanoates (PHA)).
• Nonbiodegradable bioplastics/drop-in bioplastics: bioplastics moderately produced from biomass (typically copolymerized or blended with conventional petrol-based plastics) to manufacture "bio-attributed" or "mass-balanced" plastic (e.g. Bio-PE, resin, and Bio-PET).

The first three classes are biodegradable while the last class is non-degradable (durable). Whether any kind of plastic is degradable or durable depends on its molecular structure, not on whether or not the biomass constituting the raw material is fossilized. Both durable bioplastics, such as Bio-PET or biopolyethylene (bio-based analogues of fossil-based polyethylene terephthalate and polyethylene), and degradable bioplastics, such as polylactic acid, polybutylene succinate, or polyhydroxyalkanoates, exist.

One advantage of bioplastics is their independence from fossil fuel as a raw material, which is a finite and globally unevenly distributed resource linked to petroleum politics and environmental impacts. Bioplastics can utilize previously unused waste materials (e.g., straw, woodchips, sawdust, and food waste). Life cycle analysis studies show that some bioplastics can be made with a lower carbon footprint than their fossil counterparts, for example when biomass is used as raw material and also for energy production. However, other bioplastics' processes are less efficient and result in a higher carbon footprint than fossil plastics.

Some consumer products tout the use of bioplastics as a means to earn "green" credentials. Many skeptics believe that bioplastics will not solve problems as others expect.

Bioplastics must be recycled similar to fossil-based plastics to avoid plastic pollution; "drop-in" bioplastics (such as biopolyethylene) fit into existing recycling streams. On the other hand, recycling biodegradable bioplastics in the current recycling streams poses additional challenges, as it may raise the cost of sorting and decrease the yield and the quality of the recyclate. However, biodegradation is not the only acceptable end-of-life disposal pathway for biodegradable bioplastics, and mechanical and chemical recycling are often the preferred choice from the environmental point of view.

Biodegradability may offer an end-of-life pathway in certain applications, such as agricultural mulch, but the concept of biodegradation is not as straightforward as many believe. Susceptibility to biodegradation is highly dependent on the chemical backbone structure of the polymer, and different bioplastics have different structures, thus it cannot be assumed that bioplastic in the environment will readily disintegrate. Conversely, biodegradable plastics can also be synthesized from fossil fuels.

As of 2018, bioplastics represented approximately 2% of the global plastics output (>380 million tons). In 2022, the commercially most important types of bioplastics were PLA and products based on starch.