What is biodegradable PLA ?
PLA (polylactic acid) is a biodegradable plastic product that is in demand in the fields of straws, disposable tableware, shopping bags, etc. The traditional production model of PLA is mostly made from corn and cassava. Degradable plastic is the process of adding some additives to promote its degradation function in the production of plastic, or synthesizing itself with degradation properties of plastic, or using renewable natural raw materials manufactured plastic, in use and preservation period can meet the original application performance requirements, and after use in a specific environment, so that it can be in a relatively short period of time, the chemical structure of significant changes in the loss of certain properties of exotic plastics.
Biodegradable PLA products (PLA full degradation) is a relatively advanced environmentally friendly product. It takes starch as the main raw material, adds plant fiber powder and special additives, and is processed by chemical and physical methods to make biodegradable products. Since starch is a biodegradable natural polymer, it decomposes into glucose under the action of microorganisms, and later into water and carbon dioxide. In addition, the material it is co-blended with is also a fully degradable material, so it can be said to have no impact on the environment.
PLA is one of the mainstream degradable plastic products. PLA is a polymer made by polymerizing lactic acid as the main raw material and is currently the most mature, productive, and widely used biodegradable plastic in the world.
What is biodegradable PLA tableware?
Biodegradable PLA tableware material is mainly obtained by fermentation of plant starch, and the temperature resistance of pure raw material is 60 degrees, after modification, it can reach 110 degrees or above. If compared with other plastic tableware, it is indeed the safest, can not be broken, and can be completely degradable. But because the raw material is opaque or translucent, so it can not look as good as PP or PC tableware, only solid color opaque.
The PLA Total Degradation Lunch Box Production Line applies supercritical foaming technology, low shear, high-efficiency plasticizing elements, and gradual expansion controllable foaming molding. The modification of PLA with nano-montmorillonite overcomes the difficulties of narrow temperature processing range and extrusion foaming due to the poor toughness, heat resistance, gas permeability and melt strength of the PLA material. It is difficult to obtain a high rate and high-quality cellular structure foamed material. The processing temperature range of the material is widened, the cell structure is optimized, and the bubble growth process is highly controlled to produce high-quality foamed PLA material.
Biodegradable fast-food containers made of polylactic acid (PLA) will play a key role in improving the level of urban environmental protection and reducing the consumption of irreplaceable petroleum resources.
Cyclic degradation of PLA ( polylactic acid)
1. PLA is a new type of degradable material, which can be made by extracting starch from renewable plants such as corn, potato, and cassava.
2. The starch is fermented to produce lactic acid.
3. Lactic acid is then chemically synthesized and polymerized into PLA.
4. PLA is made into various plastic products: tableware, medical screws, surgical sutures, agricultural land film, spinning silk, packaging materials.
5. After disposal, waste is completely degraded by microbes to produce water and carbon dioxide.
Synthesis method of PLA ( Polylactic Acid)
1. Direct polycondensation method
-Melt polymerization method: low process cost, high yield, the pure product can be obtained without separation; product molecular weight is small, difficult to precipitate.
-Solution polymerization method: system azeotropic, avoid polymer degradation; need a lot of solvents, high cost; complex operating equipment, purification difficulties. No industrial production examples.
-Melt-solid phase polymerization method: no solvent, low cost, easy operation, short process line; by-products are difficult to remove, the polymer molecular mass is low, the temperature is high, the product is colored.
2. Ring-opening polymerization method (based on catalyst classification)
-Anionic ring-opening polymerization: alkoxy or alkoxy alkali metal compounds as initiator. High activity, fast; prone to racemization reaction, difficult to prepare high molecular weight PLA.
-Cationic ring-opening polymerization: protonic acid and halide catalysts, high reaction temperature, the large amount of catalyst, the product molecular weight are not high, more than 20,000.
-Ligand type ring-opening polymerization: the most used method at home and abroad. Organic aluminum, rare piles of earth, tin compounds as initiators, the most commonly used is stannous octanoate. The PLA obtained is highly hydrophilic and has a high relative conversion rate, but the tin salt has a certain degree of toxicity, and whether it can be used safely in the long term remains to be proven.
Enzyme-catalyzed ring-opening polymerization: the mechanism of enzyme-catalyzed polymerization needs to be studied, and the relationship between enzyme-catalyzed polymerization and enzyme-catalyzed degradation needs to be further studied.
Decomposition conditions of PLA (polylactic acid)
Lactic acid is spinogenic and has PLLA, PDLA, and PDLLA (racemization). In the natural environment, hydrolysis occurs first, through unstable ester bonds in the main chain to oligomers, and then microorganisms enter the tissue and break it down to carbon dioxide and water. Under composting conditions (high temperature, high humidity), the hydrolysis reaction can be easily completed and the decomposition is faster. Microorganisms that can decompose PLA are commonly found in nature, such as Fusarium Candida, Penicillium, and Humicella.
PLA (polylactic acid) degradation factors
1. Crystal PH value: PLA degradation rate in alkaline condition > acidic condition > neutral condition.
2. Crystallinity: degradation rate of amorphous > degradation rate of crystalline material. Water penetrates into the amorphous region first, leading to the breakage of ester bonds; during the hydrolysis of the amorphous region, low molecular substances with the regular structure are generated, and the crystallinity increases, delaying the further hydrolysis.
3. Molecular weight and molecular weight distribution: molecular weight is inversely proportional to the degradation rate; the wider the molecular weight distribution, the faster the degradation rate.
4. Influence of conformational regularity: Under alkaline conditions, the degradation rate is PDLA (PLLA) < P (LDL)A < PDLLA.
5. Enzymes: PLA main chain contains ester bonds, which can be accelerated by esterases, such as Rhizobium esterase, porcine pancreatic esterase, and porcine liver clostridial esterase.
Applications of PLA (polylactic acid)
1. Food grade material: PLA film has the advantages of high transparency, high gloss, etc. It also has a long-lasting pleasant aroma and high-quality air permeability, which can make net dishes, bread, doughnuts, etc. stay fresh and can be widely used as disposable tableware and food packaging materials. Production of children’s tableware and household products needs to test whether the content of formaldehyde, BPA, heavy metals, etc. exceeds the standard.
2. Textile fiber field: With the partial maturity of the PLA fiber polymerization process, PLA is considered one of the most promising “green” fibers. It has core moisture absorption and conductivity, good UV resistance and bacteria resistance, excellent flame retardancy, excellent resilience, and drapability. Therefore, the nonwoven fabric made of PLA fiber is very versatile. They can be used as surgical gowns, surgical coverings, masks, etc. They can also be used as fabrics for diapers, women’s sanitary napkins, and other physiological hygiene products. It can be used as clothing material, wipe cloth, handbag, and other daily necessities.
3. Biomedical field: It can be used as surgical suture, drug control release system, tissue engineering, fracture internal fixation material, gene therapy carrier, ophthalmic material, cosmetic microplastic material, etc.
4. Electronic technology field: In order to save petroleum resources and reduce the earth’s greenhouse effect, and further expand the application field of PLA, many Japanese companies have conducted in-depth research on the application of PLA in the field of electronic appliances and have achieved excellent results.
PLA tableware does not have any odor, and it is easy to drink water and soup. PLA itself is a fully degradable material. But after denaturing, it increases the difficulty of total degradation, some can only reach 70% degradation. Meanwhile, the price of raw materials is high, and the price of biodegradable PLA tableware products is necessarily high, so, even though the attitude of many restaurants and hotels toward this kind of tableware is more recognized, but due to the cost of most reluctant to replace.
Compostable Sugarcane Bagasse Tableware
Compared with corn starch biodegradable PLA tableware, compostable sugarcane bagasse tableware has a lower production cost and is more practical. 80% or more of bagasse is used in sugarcane bagasse tableware, which is made of bagasse from sugar cane juice and is very environmentally friendly. Sugarcane bagasse tableware and corn starch tableware production principle are basically the same, and even the equipment can be common to a large extent, the original production of corn starch tableware equipment slightly modified, can be used to produce bagasse tableware.
The pulp made from bagasse has good strength, toughness, and high whiteness, while bagasse fiber is a natural fiber, non-toxic, non-side effects, non-polluting, recyclable, and the part that can’t be recycled can be naturally degraded in nature after two months of time. Compared with other raw materials, such as wood, reed, and straw, sugarcane bagasse tableware has a high qualification rate (higher than 99%), high physical strength, good waterproof and oil-proof performance, low production cost (30% lower than wood pulp products) and no toxic side effects.
The sugarcane bagasse tableware has the advantages of high qualification rate (higher than 99%), high physical strength, good water, and oil resistance, low production cost (30% lower than wood pulp products), no toxic side effects, etc. It ranks first in the comprehensive evaluation of the existing “alternatives to disposable foamed plastic tableware” organized by the State Environmental Protection Administration and the State Economic and Trade Commission’s “White Pollution” Replacement Office.
The strength of compostable sugarcane bagasse tableware is much higher than that of foamed plastic, and it is oil- and water-resistant, not easy to break, can be streamed at high temperature, suitable for microwave ovens, and can also be put into refrigerators.
Paper tableware
By the way, in addition to biodegradable PLA tableware and compostable sugarcane bagasse tableware, paper material food packaging containers are also well known to the public. Paper is the most familiar type of material, so “paper instead of plastic” is naturally the first solution people think of. Paper-plastic technology is the use of paper pulp as raw material, molding, and drying in the mold to produce disposable tableware.
Advantages: this method of making tableware because of its non-toxic, non-hazardous, easy to recycle, renewable, biodegradable, and other advantages of the title of “environmentally friendly products”, is currently a comprehensive evaluation of the better alternative technology.
Disadvantages: The technology also has shortcomings when evaluated from the whole process of paper production and use. One is that the production of pulp requires large amounts of forest resources, and forest resources on earth are limited, and a large amount of deforestation causes soil erosion, so it does not meet our national conditions; on the other hand, the production of the pulp can cause serious water pollution, and in some cases, the pollution level even exceeds that of plastic.
So from the macro point of view, paper instead of plastic technology can not completely eliminate the pollution of the environment, but only the tableware to the environment in advance of the pollution of the environment when making lunch boxes. Moreover, the high production cost of paper pulp makes the price of paper tableware produced from pulp is also relatively high, so paper instead of plastic is not the perfect solution.
In summary, environmentally friendly compostable sugarcane bagasse disposable tableware is our best choice to eliminate the use of environmentally unfriendly and environmentally polluting disposable tableware, to contribute to the protection of our planet.
For more details, please contact UV Tableware for an in-depth discussion, thank you.
