Starch is a natural polyglucose polymer compound, a nutrient stored in plants. It is widely present in the fruits, rhizomes and leaves of plants in the form of granules, and is a source of carbohydrates for human food. Starch is rich in resources, low in price, and viable. It is not only closely related to human survival, but also used in food, paper, textile, petroleum, chemical, pharmaceutical, and construction industries.
Starch is also a natural degradable polymer. Under the action of microorganisms, starch macromolecules can be broken down into monosaccharides such as glucose and other small and medium molecular compounds, and finally metabolized into H2 O and CO2.
As a renewable natural resource, starch is easily available in value. As a filler, it can promote the degradation of the matrix resin. The processing and modeling can use the existing filling plastic processing technology and equipment, and the performance is close to or equivalent to the matrix resin, and can reach general Application requirements, and non-toxic and harmless in the use process, so in the several types of degradable plastics that have been industrialized so far, starch-filled plastics are very competitive and promising all-starch plastics generally refer to starch-containing plastics in 90 % Above, adding processing aids, processing and production under the condition that the starch has thermoplastic properties, so it is also called thermoplastic starch plastic. Starch and other additives in all-starch plastics can be completely degraded.
Starch-based plastics can be divided into two types: one is to fill starch into traditional plastics such as polyethylene (PE), propylene ethylene (PP) and other plastics to form alloys. When starch is blended into non-degradable traditional plastics, The resulting blended plastics are often not biodegradable; the other is to blend starch and other biodegradable polymer materials to form alloys.
If starch is mixed with other natural macromolecules, such as glue, cellulose, galactose, chitin, etc., into a completely biodegradable material, starch can also be blended with other biodegradable polymers, such as polycaprolactone, polylactic acid, Polyhydroxyalkanoates (such as polyhydroxybutyrate, polyhydroxyvalerate, polyhydroxybutyrate valerate, etc.), polybutenoic acid succinate, etc., and then processed into products.
The blend of starch and biodegradable polymer has biodegradable properties. A simple schematic diagram of the processing route of starch-based plastics and the biodegradability of the final product is as follows.