Bioplastics are plastics derived from renewable feedstocks, such
as starch, cellulose, vegetable oils and vegetable fats. They may or
may not be biodegradable and some are only partially biobased, that
is they contain both renewable and fossil-fuel-based carbon. Both
the amount of biobased constituents and the conditions under which
these polymers biodegrade can vary widely. Depending upon the composition, degree of crystallinity, and environment, degradation
times can range from several days to several years.
The development of
biodegradable bioplastics has gained a lot attention in recent years.
Whether these new plastics will gain a significant market share will partly
depend on how strongly society is committed to protect the environment, i.e.
to reduce waste, and to conserve irreplaceable fossil fuels. Many obstacles
such as high(er) price and limited production capacity have to be overcome before biobased and biodegradable polymers will
gain a significant market share.1
Starch is one of the most abundant biopolymers. It is completely biodegradable, inexpensive, renewable and can be easily chemically modified. Like cellulose, starch can be considered a condensation polymer because its hydrolysis yields glucose molecules. The cyclic structure of the starch molecules together with strong hydrogen bonding gives starch a rigid structure and leads to highly ordered crystalline regions. To reduce its brittleness and to improve its mechanical and physical properties, starch is often chemically modified and blended with other biopolymers. Starch based bioplastic are mainly used for packaging such as cups, bowls, bottles, cutlery, egg cartons, and straws. Other applications include disposable bags and trash liners as well as compostable films for agriculture.
Polylactic acid (PLA) is one of the most important biodegradable and biobased thermoplastics. Most commercial high-purity grades are semicrystalline, have high transmittance (> 90 %), and high yield and tensile strength. Many commercial grades are specifically designed for thermoforming, and extrusion / injection molding. Typical applications of PLA are disposable tableware articles like drinking cups, cutlery, trays, food plates and food containers. Some other (potential) applications include soil retention sheething and other agriculture films, waste and shopping bags, and the use as packaging material in general. PLA can also be spun into fibers which could be used for the manufacture of woven and non-woven biodegradable one-use fabric articles such as disposable garments, feminie hygine products, and diapers.
Poly(1,4-butylene succinate) (PBS) is a biodegradable, semi-crystalline thermoplastic synthesized from succinic acid and 1-4-butanediol. Both building blocks can be produced from renewable feedstock such as glucose and sucrose via fermentation. PBS is a very promising biopolymer because its mechanical properties are comparable with those of widely used high density polyethylene and isotactic polypropylene. PBS is a cost-effective alternative to other biopolymers such as PLA, PBAT, and PHB. Possible applications include (disposable) food packaging, mulch film, plant pots, hygiene products, fishing nets and fishing lines. It can be used as a matrix polymer or in combination with other bioolymers such as polylactic acid (PLA).
Polyhydroxybutyrate (PHB) is a melt-processable, semi-crystalline thermoplastic produced from microorganisms by fermentation of renewable carbohydrate feedstocks. PHB is a truly biodegradable and biocompatible plastic and an attractive environmental-friendly alternative to fossil-based thermoplastics. Commercial grades of PHB have properties that are very similar to those of polypropylene (PP). Typical applications of PHB are disposable tableware articles, soil retention sheething, waste and shopping bags, and the use as a packaging material in general. PHB can also be spun into fibers which could be used as surgical sutures. Other (potential) biomedical applications include drug delivery systems and biodegradable implanted medical devices.