Fully biodegradable material testing and application (below)

3, the application of biodegradable materials

Biodegradable materials are widely used in various industries and can partially replace general plastics. The largest use of environmental protection materials, packaging materials and medical materials.

3.1. Agricultural Use

The ideal agricultural material is a material that can be converted into soil-enhancing properties by synergistic action with other biodegradable materials. The biodegradable material is mainly used as an agricultural mulch and crop growth container in agriculture.

3.1.1, agricultural mulch

Traditional films have played a major role in helping crop growth and increasing crop yields, but the resulting drawback is that handling after use is very difficult. After the whole crop grows in the sun, the strength of the film is reduced and split into small pieces that remain in the soil. Small pieces can cause soil compaction, impede the development of the crop roots and absorption of water, and can also cause wind drift. Environmental pollution. Apart from the advantages of traditional plastic film, biodegradable agricultural plastic film can be automatically degraded after use, and does not have to be collected. At the same time, the demand for agricultural fertilizer and water is reduced correspondingly, and the next season of farming can be carried out, thus reducing white pollution. It can also reduce production costs.

3.1.2, crop growth containers

Crop growth containers are used for sowing and transplanting seedlings, flowers, vegetables, and bonsai. If the container is not biodegradable, the container must be removed before transplanting to enable the root system to grow rapidly, and the bare root is easily damaged, it is difficult to use mechanical planting, and the biodegradable plastic container protects the root system when planted, and the survival rate is high. Planting and transplanting in this way can reduce the cost of many plants, extend the season of transplanting, and increase the survival rate.

Studies have found that crop growth devices based on polycaprolactone are significantly biodegraded in soil, lose weight 48% after 6 months and lose about 95% after one year.

Other applications of biodegradable materials in agriculture include turfgrass cultivation tablets, composting bags, and agricultural drug release materials.

3.2. Packing purposes

Biodegradable plastic food bags, bags, and garbage bags are popular because of their biodegradability. The biodegradable packaging material is generally a biodegradable polymer added to a laminated film or a film directly blended with a laminated material. Food packaging materials and containers generally require that the food is not rotted, oxygen is isolated, and the material is non-toxic. The most representative of these are polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and its copolymer (trade name Biopol). Its physical properties are similar to those of polyethylene and polypropylene, and its heat sealability is good. Biopol can be biodegraded or burned after use. The oxygen consumption of both is only equivalent to the photosynthesis of oxygen into the atmosphere. The CO2 produced after treatment is the total amount of CO2 ingested by photosynthesis and therefore can be considered as fully entering the organism. cycle.

Biodegradable plastics can also be used as disposable cushioning materials. According to reports, the polyvinyl alcohol starch-based biodegradable plastics developed by Koki Japan Co., Ltd. are excellent buffer materials with a slightly higher apparent density than conventional polystyrene cushion materials.

3.3, medical biodegradable materials

Medical materials not only need to be medically effective, but also safe, non-toxic, non-irritating, and have good biocompatibility with the human body. The medical biodegradable material is a biodegradable material that can be decomposed and absorbed by a lytic enzyme in a living body after the medical function is completed. The biodegradable plastic has been widely used in surgical sutures, artificial skin, orthopedic surgery, in vivo drug release agents and absorbent sutures. And other fields.

3.3.1, surgical sutures

The ideal suture should have good adaptability in vivo, non-toxic and non-irritating, and can be absorbed by the tissue after being maintained in the body for a certain period of time. Its suture, knotting performance and flexibility should meet the operational requirements. The previously used gut gizzards are prone to produce antigenic reactions. Their adaptability in the human body is not ideal and their preservation is inconvenient. Studies have shown that medical sutures made of chitin and chitosan can be broken down by lysozyme in vivo and produce CO2 excreted from the body. The produced glycoprotein can be absorbed by tissues, eliminating the trouble of stitch removal after surgery and reducing the patient's pain. In urine, bile, pancreatic juice can maintain a good strength, self absorption after use, does not cause allergies, but also accelerate wound healing.

3.3.2, artificial skin

Human skin is a highly regenerative tissue, but large areas of burns cannot be cured by skin alone or by autograft skin. Artificial skin is needed as a temporary wound protection cover material in the treatment process to help heal.

The role of artificial skin: to prevent evaporation and loss of water and body fluids through the wound; to prevent infection; can promote the growth of granulation or epithelial, and promote healing. Artificial skin can also be disinfected and detoxified to prevent bacterial infections and not harmful to the human body. A large number of commercially available artificial skins include collagen, chitin, poly-L-leucine and other enzyme-catalyzed biodegradable materials.

3.3.3, drug release agent

After the drug is taken orally into the body, the concentration in the blood must reach a certain level before it can play a physiological activity. When the drug blood drug depth is higher than a certain limit, there will be side effects, and when the blood drug is metabolized by the body metabolism After in vitro, the decrease in plasma concentration does not have efficacy. The drug sustained-release preparation made of biodegradable macromolecule material can maintain long-term constant release of the drug in the human body, improve the curative effect, and is convenient and effective for long-term treatment of cancer, heart disease, hypertension and the like.

In addition to the above uses, medical biodegradable materials can also be used for fracture fixation materials, artificial kidneys, medical anti-adhesives and other uses.

4 Conclusion

With the continuous reduction of petroleum resources and people's attention to their environment, biodegradable polymer materials have received more and more attention. Fully biodegradable polymer materials are difficult to further expand due to their high production cost, and the starch-based degradable plastics are not completely degraded after starch-based degradation. It is not clear whether the decomposed products will cause secondary pollution. How to solve the current environmental problems, the author believes that first of all should emphasize the recycling, classification, processing of waste plastics, so that limited resources recycling; followed by the study of fully biodegradable polymer materials, the use of cheap and readily available raw materials by microbial fermentation And use of transgenic plants to produce biodegradable polymer materials.