Biobased degradation refers to the process of using biomass or its derivatives as raw materials and ultimately decomposing them into water, carbon dioxide, and other composting materials through microbial action. This process is different from biobased plastics. Biobased plastics mainly focus on the raw materials of plastic products partially or entirely coming from biomass, while biodegradation focuses on the decomposition process of materials such as plastics in the natural environment.

The specific process of biodegradation includes three steps: first, the water vapor on the surface of the material or the water molecules in the liquid will interact with the material surface to form a hydration layer; Then, microorganisms will attach to the surface of the material and begin to decompose its organic components; Finally, organic components are further decomposed into inorganic substances such as carbon dioxide and water, which can be absorbed and utilized by plants. There are many biodegradable materials, and below we will focus on degrading PLA and PBS.

Polylactic acid (PLA): also known as polylactide, is a polymer obtained by polymerization of lactic acid as the main raw material, belonging to the polyester family. The production process of PLA is pollution-free and the product is biodegradable. Waste PLA can be decomposed into carbon dioxide and water through composting at temperatures above 55 ℃ or through the action of enriched oxygen and microorganisms, achieving natural material circulation without any impact on the environment. At present, the production of PLA mainly adopts the propylene glycol ester ring opening polymerization process. Firstly, lactic acid is dehydrated to form oligomers, followed by depolymerization to form lactide, followed by ring opening polymerization to form PLA. The disadvantage of PLA is that the degradation conditions are relatively harsh. However, due to the relatively low cost of PLA in biodegradable plastics, its consumption is among the top.

Polybutylene succinate (PBS) is an aliphatic polyester produced by dehydration of succinic acid and butanediol through condensation reaction. It has a milky white appearance, is odorless and tasteless, and is easily degraded into carbon dioxide and water due to its good biocompatibility and bioabsorbability. It is a typical fully biodegradable material.

PLA has poor toughness, lacks elasticity and flexibility, has a hard and brittle texture, relatively low melt strength, and slow crystallization rate. These defects limit its application in many aspects. The chemical structure of PLA contains a large number of ester bonds, which leads to poor hydrophilicity and requires controlled degradation rate.

PBS is a polyester with high crystallinity and good mechanical properties. Its mechanical strength is similar to that of general plastics such as polypropylene and polyethylene, and it can be suitable for preparation processes such as injection molding, extrusion, blow molding, and lamination.

Comparison of performance between PLA, PBS and traditional membrane bag materials:

Biodegradable plastics can be made into various products, such as disposable tableware, shopping bags, packaging materials, etc., with a wide range of applications that can meet people’s daily needs. This also means that this material has broad application prospects and market potential.

Overall, the significance of developing degradable plastics lies not only in solving the environmental problems caused by traditional plastics, but also in promoting the process of sustainable development.