Green Opportunities for Biodegradable Plastic Bags in the Era of the Plastic Restriction Order

The degradation mechanisms of biodegradable plastic bags mainly include biodegradation, photodegradation and water degradation. Biodegradation means that under the action of microorganisms such as bacteria and fungi, the high-molecular polymers of plastic bags are broken down into low-molecular compounds, and eventually turn into carbon dioxide, water and other harmless substances to return to nature. Photodegradation is realized by adding photosensitizers into plastics. When plastic bags are exposed to light, the photosensitizers trigger photochemical reactions to break the plastic molecular chains for degradation.

There are also various types of materials used to make biodegradable plastic bags. Polylactic Acid (PLA) is a common biodegradable material. It is a polymer polymerized mainly from lactic acid, which can be extracted by fermenting crops such as corn and potatoes. PLA features excellent biodegradability and biocompatibility. In natural environments, microorganisms can decompose PLA into carbon dioxide and water without causing environmental pollution. Meanwhile, PLA boasts good gloss and transparency, delivering attractive appearance for finished products, as well as certain mechanical strength to meet daily usage requirements.

Polycaprolactone (PCL) is another biodegradable material. It is a semi-crystalline linear aliphatic polyester, generally produced by ring-opening polymerization of caprolactone initiated by initiators. PCL has favorable biocompatibility and thermally responsive shape-memory properties, and can be completely degraded within 6 to 12 months in natural conditions. It is compatible with multiple processing methods including extrusion, injection molding and film blowing, so it is widely adopted in biodegradable plastic bags and other biodegradable plastic products.

Besides, other biodegradable materials such as Polyhydroxyalkanoates (PHA), Polybutylene Succinate (PBS), as well as their blends with natural materials like starch, are also used for manufacturing biodegradable plastic bags. These materials have respective advantages: some offer superior mechanical properties while others come at lower costs. By combining different materials and optimizing formulations, manufacturers can produce biodegradable plastic bags with better performance that fit market demands.

The application scenarios of biodegradable plastic bags keep expanding. In traditional sectors such as supermarkets, catering and food delivery, biodegradable plastic bags are gradually replacing conventional plastic bags. Many supermarkets provide biodegradable shopping bags, and the catering industry increasingly uses biodegradable plastic bags for takeaway packaging. In the medical sector, thanks to environmental friendliness and safety, biodegradable plastic bags can be applied to packaging of certain medical devices and collection of medical waste to reduce potential environmental contamination. In agriculture, biodegradable mulch film is a key application of these materials. Traditional mulch film is hard to degrade; its residues in soil damage soil structure and hinder crop growth. In contrast, biodegradable mulch film degrades naturally after service life, leaving no long-term harm to soil and supporting sustainable agricultural development.