Basic knowledge of polylactic acid

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Polylactic acid has good biodegradability; it can be completely degraded by microorganisms in nature after use, ultimately producing carbon dioxide and water without polluting the environment, which is highly beneficial for environmental protection. Polylactic acid possesses good mechanical and physical properties, is suitable for various processing methods such as blow molding and thermoplastic processing, is easy to process, and is widely used. It can be used to process a variety of plastic products for both industrial and consumer use, food packaging, fast-food containers, non-woven fabrics, as well as industrial and household textiles. Further processed into agricultural fabrics, health-care fabrics, rags, sanitary products, outdoor UV-blocking fabrics, tent fabrics, floor mats, and so on, it holds very promising market prospects. Polylactic acid possesses good solubility and biodegradability, and it is widely used in the pharmaceutical industry; for example, it can be used to manufacture disposable infusion devices and self-sealing surgical sutures, while low-molecular-weight polylactic acid is employed as a packaging material for drug release. Synthesis of polylactic acid: Polylactic acid (PLA) is a new type of biodegradable material. It can be produced from starch through continuous lactic acid fermentation and a continuous solvent-free lactic acid polymerization process. Polylactic acid can be used as a raw material to produce fully biodegradable plastics, which have broad application prospects in the fields of environmental protection, medicine, and everyday packaging. It is a new recyclable and reusable material that aligns with modern environmental protection trends. Polylactic acid is a new type of plastic that stems from the concept of natural recycling – a concept that is the opposite of traditional plastics used today. It is not made from limited petrochemical resources (oil), but rather from renewable plant resources such as corn, whose starch serves as the raw material. Starch raw materials can be converted into lactic acid through a fermentation process, which is then transformed into polylactic acid via chemical synthesis. Significant breakthroughs were achieved in the 1990s in the technology for converting glucose into lactic acid, and improvements in polylactic acid production techniques have reduced its manufacturing costs. Degradation of polylactic acid: The degradation of polylactic acid occurs in two stages: it is first degraded through hydrolysis, and then by microorganisms. Hydrolysis occurs first in the natural environment, and then microorganisms enter the tissue and break it down into carbon dioxide and water. Under composting conditions (high temperature and high humidity), the hydrolysis reaction can be carried out easily, and the decomposition rate is also fast. In an environment where hydrolysis reactions are unlikely to occur, the decomposition process is gradual. Traditional petrochemical raw materials increase carbon dioxide emissions, but polylactic acid does not exhibit this behavior; the carbon dioxide produced during its decomposition can be reused as carbon atoms required for plants to carry out photosynthesis. Properties of polylactic acid: In addition to the basic properties of biodegradable plastics, polylactic acid also possesses its own unique characteristics. Traditional biodegradable plastics lack the strength, transparency, and resistance to climate change of conventional plastics. Polylactic acid has similar basic physical properties to petrochemical synthetic plastics; in other words, it can be widely used to manufacture a variety of application products. Polylactic acid also possesses good luster and transparency, comparable to that of films made from polystyrene, a feature that other biodegradable products cannot offer. Polylactic acid possesses the best tensile strength and ductility. It can also be produced using various conventional processing methods, such as melt extrusion, injection molding, film blowing, foaming, and vacuum forming; its molding conditions are similar to those of polymers widely used today. In addition, it has the same printing properties as traditional films. In addition to rigid polylactic acid, elastic polylactic acid has also been developed, allowing polylactic acid to be used to create a variety of application products to meet the needs of different industries. Polylactic acid films have good breathability, oxygen permeability, and carbon dioxide permeability; they also possess the ability to block odors. Viruses and molds tend to attach to the surface of biodegradable plastics, raising concerns regarding safety and hygiene. However, polylactic acid is the only biodegradable plastic that possesses excellent antibacterial and antifungal properties. When polylactic acid is incinerated, its heat of combustion is the same as that of paper, and it is half that of traditional plastics such as polyethylene; moreover, incinerating polylactic acid does not release any toxic gases such as nitrides or sulfides. The human body also contains lactic acid in its monomeric form, which indicates the safety of this breakdown product. Applications of polylactic acid: The processing of polylactic acid products can utilize conventional plastic manufacturing techniques. Based on the properties of polylactic acid, various products have been developed, including films, sheets, fibers, and ropes. 1. Food packaging materials. 2. Packaging materials for integrated circuits: It is very difficult to achieve 100% recycling of semiconductor packaging materials. For such materials, high requirements are placed on strength, dimensional accuracy, antistatic properties, and color; polylactic acid performs exceptionally well in these aspects. After use, it can be disposed of safely without producing any harmful substances. 3. Agriculture, horticulture, and floriculture: Burning large amounts of collected waste generates harmful substances, as well as smoke and unpleasant odors, which have a negative impact on the surrounding environment and residents. Japan will completely ban open-air burning and outdoor accumulation in October 2004; as a result, the issue of how to handle agricultural waste and other agricultural materials has gradually come to the fore. A farm in Aichi Prefecture uses PLA as climbing ropes and covering films for melons, which makes the crop cultivation process more environmentally friendly and beneficial to humans. Livestock manure can also cause serious environmental problems. To address this issue, local agricultural associations have rapidly established large-scale composting facilities across the country to compost agricultural waste along with animal manure. 4. The emergence of polylactic acid is not limited to reforms in the industrial sector; it will also bring about significant changes in everyday home life. In daily family life, many aspects are related to plastic films and packaging. Most petrochemical products are considered waste that is discarded everywhere, and recycling such waste requires expensive costs. However, polylactic acid can be decomposed and can be processed at home. 5. Toys: Polylactic acid possesses many unique properties that are not found in traditional biodegradable plastics; it is safe, hygienic, and antibacterial. By leveraging these excellent properties, it is hoped that the applications of polylactic acid can be expanded. It is expected that in the near future, polylactic acid will replace traditional petroleum-based plastics and become an essential part of our daily lives. Polylactic acid will lead us into a society of resource recycling and reuse.