The materials of degradable pet food bags mainly include the following categories.
Biodegradable Plastics
Polylactic Acid (PLA)
It is made from renewable resources such as corn and sugarcane through fermentation. It has good biocompatibility and biodegradability, and can be decomposed into carbon dioxide and water by microorganisms under composting conditions. It has high transparency and good mechanical properties, but its thermal stability is relatively poor, and the operating temperature should not be too high.
Polyhydroxyalkanoates (PHA)
It is a polyester synthesized by microorganisms under specific conditions. It has excellent biodegradability and biocompatibility, and can be rapidly degraded in the natural environment. Its properties are similar to those of traditional plastics, with good flexibility and strength. However, the production cost is relatively high, which limits its large-scale application.
Starch-based Plastics
They are made by blending starch as the main raw material with other biodegradable polymers. Starch is a renewable resource with a wide source and low price. It has a certain degree of biodegradability, and its degradation performance is greatly affected by the starch content and the composition of the blend. The higher the starch content, the faster the degradation rate, but the mechanical properties of the material may decline.
Natural Polymer Materials
Cellulose
It is the main component of the plant cell wall, with good biodegradability and renewability. After chemical modification, cellulose can be made into cellulose derivatives, such as carboxymethyl cellulose (CMC), ethyl cellulose (EC), etc., which can be used to prepare degradable packaging materials. It has good air permeability and certain mechanical strength, but its water resistance is relatively poor, and waterproof treatment is usually required.
Chitosan
It is a natural polysaccharide obtained by deacetylation of chitin, with good biodegradability, biocompatibility and antibacterial properties. It can be made into a film for packaging, which can effectively prevent food from deteriorating and is friendly to the environment. However, the mechanical properties of the chitosan film need to be further improved, and it generally needs to be used in combination with other materials.
Protein-based Materials
Common ones include soybean protein, gelatin, etc. These proteins have a rich source and can be processed into packaging materials with certain properties. They have good biodegradability and biocompatibility, but their water resistance and temperature resistance are poor, and they are easily eroded by microorganisms, so appropriate modification and treatment are required.
Inorganic Mineral Filling Materials
They are mainly some degradable inorganic minerals, such as calcium carbonate, talcum powder, etc., which can be mixed with biodegradable polymers to make composite materials. They can not only reduce the cost but also improve certain properties of the materials, such as increasing the rigidity and heat resistance of the materials. To a certain extent, they also contribute to the degradation of the materials, because inorganic minerals can promote the breakage and decomposition of polymer molecular chains. However, if the filling amount is too high, it may lead to a decline in the mechanical properties and processing performance of the materials.