Application of Polylactic Acid

In order to solve the problem of “white pollution” caused by non-degradable materials, various countries are vigorously researching and developing new degradable materials. Polylactic acid, also known as polypropylene glycol, is referred to as PLA (Polylactic acid). The common method of its industrial synthesis is to extract starch from corn, wheat, straw and other grains or plant straws, then produce glucose under the action of amylase, and then obtain lactic acid by fermentation, and finally make it through a series of chemical synthesis. After hydrolysis or microbial decomposition, carbon dioxide and water will be generated, which is non-polluting to the atmosphere and soil. It has excellent controlled degradability, biocompatibility, better film formation and crystallization properties, and is considered as the most promising biodegradable polymer material.

Application of PLA

1.1 Biomedical field

1.1.1 Drug slow release materials

When polylactic acid is used as a slow-release drug carrier, there are miniature coating films that can effectively control the drug dose to be released smoothly; there are also drug slow-release capsules that effectively prolong the drug release time and keep the blood and drug concentration in relative balance, reducing the stimulation and toxic side effects caused to human organs such as the gastrointestinal tract when the drug is absorbed centrally.

1.1.2 Orthopedic internal fixation materials

Orthopaedic internal fixation materials are often used in orthopaedic surgery, and most of them use stainless steel metal materials. Long-term use will cause osteoporosis, its own bone degeneration and other problems. The emergence of polylactic acid not only makes up for the defects of metal materials, but also eliminates the physical and economic burden caused by secondary surgery after healing.

1.1.3 Surgical sutures

PLA and its polymers have certain mechanical strength and tensile strength, can control the degradation rate, and the sutures can be automatically degraded and absorbed by the body during the wound healing process, which has received wide attention from the medical community and has been used in various surgeries.

1.1.4 Tissue engineering scaffold materials

When polylactic acid is implanted as an extracellular matrix in the body, it can promote the gradual development of seed cells into a fully functional tissue. At present, some tissue scaffolds such as cartilage, skin, nerve, tendon, etc. have achieved remarkable research results.

1.2 Agricultural production areas

Most of the more widely used mulch films are made of chemical fibers , and the components are mainly polyvinyl chloride or polyethylene. Shredded films are difficult to degrade and accumulate in the soil for a long time, causing gradual soil slumping, reduced permeability, and reduced crop yield. Biodegradable mulch can be classified into starch-based degradable mulch, liquid degradable mulch and cellulose-based biodegradable mulch. Starch-based biodegradable mulch is difficult to manipulate because of its fast degradation rate and weak mechanical performance; liquid biodegradable mulch has better degradation performance but higher cost; cellulose biodegradable mulch is green and renewable, with good breathability and moisture permeability, resulting in poor thermal insulation effect. When PLA is used as biodegradable mulch film, it not only makes up for the defects of polluted environment and difficult to clean such as polyethylene agricultural mulch film, but also has good mechanical properties, gloss and light transmission rate.

At present, the research and development of PLA biodegradable materials is a green industry in China, relying on policy guidance and government support, and has been widely recognized and promoted. However, PLA has disadvantages such as high raw material cost and complicated synthesis process technology, which need further research and experiment to find a solution. While the awareness of environmental protection is increasing, PLA will be applied to more products and gradually replace non-renewable materials to solve the problems such as resource shortage. The discovery of such materials as PLA will make a great contribution to the construction of an environmentally friendly and sustainable society in China.