Bioplastics are plastics derived from renewable biomass sources, such as vegetable fats and oils, corn starch, pea starch or microbiota. Common plastics, such as fossil-fuel plastics, are derived from petroleum; these plastics rely more on fossil fuels and produce more greenhouse gas. Some, but not all, bioplastics are designed to biodegrade. Biodegradable bioplastics can break down in either anaerobic or aerobic environments, depending on how they are manufactured. There is a variety of materials that bioplastics can be composed of, including: starches, cellulose, or other biopolymers. Some common applications of bioplastics are packaging materials, dining utensils, food packaging, and insulation.
Constituting about 50 percent of the bioplastics market, thermoplastic starch, currently represents the most widely used bioplastic. Pure starch possesses the characteristic of being able to absorb humidity, and is thus being used for the production of drug capsules in the pharmaceutical sector. Flexibiliser and plasticiser such as sorbitol and glycerine are added so the starch can also be processed thermo-plastically. By varying the amounts of these additives, the characteristic of the material can be tailored to specific needs (also called "thermo-plastical starch"). Simple starch plastic can be made at home.
Industrially, starch-based bioplastics are often blended with biodegradable polyesters. These blends are mainly starch/polycaprolactone or starch/Ecoflex (polybutylene adipate-co-terephthalate produced by BASF). These blends remain compostables. Other producers, such as Roquette, have developed another strategy based on starch/polyeolefine blends. These blends are no longer biodegradables, but display a lower carbon footprint compared to the corresponding petroleum-based plastics.
Cellulose bioplastics are mainly the cellulose esters, (including cellulose acetate and nitrocellulose) and their derivatives, including celluloid.
Genetic modification (GM) is also a challenge for the bioplastics industry. None of the currently available bioplastics – which can be considered first generation products – require the use of GM crops, although GM corn is the standard feedstock.
Looking further ahead, some of the second generation bioplastics manufacturing technologies under development employ the "plant factory" model, using genetically modified crops or genetically modified bacteria to optimise efficiency.
The environmental impact of bioplastics is often debated, as there are many different metrics for "greeness" (e.g. water use, energy use, deforestation, biodegredation etc) and tradeoffs often exist. The debate is also complicated by the fact that many different types of bioplastics exist, each with different environmental strengths and weaknesses, so not all bioplastics can be treated as equal.
While production of most bioplastics results in reduced carbon dioxide emissions compared to traditional alternatives, there are some real concerns that the creation of a global bioeconomy could contribute to an accelerated rate of deforestation if not managed effectively. There are associated concerns over the impact on water supply and soil erosion.
At one time bioplastics were too expensive for consideration as a replacement for petroleum-based plastics. The lower temperatures needed to process bioplastics and the more stable supply of biomass combined with the increasing cost of crude oil make bioplastics' prices more competitive with regular plastics.
Source: Wikipedia (All text is available under the terms of the Creative Commons Attribution-ShareAlike License)