Polylactide, commonly referred to as PLA, is a polymer made from renewable resources.
In contrast to other petroleum-based thermoplastics, most of the raw materials used in PLA production include corn starch, cassava or sugar cane.
However, its performance is comparable to other plastics in the industry.
The consumers’ desire to use less harmful materials have triggered PLA rapid entry into the plastics market as a competitive commodity.
In this article, we will focus on the PLA plastic itself, including the composition,benefits, drawbacks and production methods.
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PLA is a carbohydrate source produced by the fermentation of polyester under controlled conditions, such as corn starch or sugar cane.
Its components can be lactic acid or lactide monomers.
Then they will be polymerized into PLA.
At first, corn is wet milled.
The starch has been separated and then mixed with acid or enzyme and heated.
This process “breaks” starch into glucose (d-glucose) or corn sugar.
Finally, glucose fermentation produces l-lactic acid, which will be the basic part of PLA.
Two ways for preparing polylactic acid plastics using lactic acid as raw materials are introduced.
The first way is to use lactide as an intermediate state, which leads to a larger molecular weight.
The second way is the direct polymerization of lactic acid.
Polylactic acid is bio-based and biodegradable.
These are the most prominent features, especially considering that one does not mean the other.
Bio-based means that the material is derived from biomass.
Being biodegradability, polylactic acid will be transformed into natural materials such as carbon dioxide, water and other composite materials.
This process is carried out by microorganisms in the environment and strongly depends on conditions such as temperature and humidity.
PLA is a thermoplastic, which means it can be melted and reshaped without significantly reducing its mechanical properties. Therefore, PLA is recyclable.
It comes from renewable resources and is in stark contrast to petroleum-based plastics, whose availability is limited.
Carbon neutral: its renewable energy actually absorbs carbon.
It does not release toxic gases when oxygenated.
Economic potential: Bioplastics provide a growing market and provide opportunities for job creation and development in rural areas. European Bioplastics estimates that by 2030, the European bio market will create as many as 300,000 highly skilled jobs, more than 10 times the current number.
PLA plastic is considered safe by the US Food and Drug Administration.
In addition, it is safe for all food packaging applications.
Its non-toxicity allows it to be used in the medical field.
Decompose slowly outside of a controlled environment.
Although polylactic acid plastic is biodegradable, only under specific and controlled composting conditions, that is, with commercial composting facilities, can polylactic acid plastic be degraded within 3 months.
In a landfill, it may take 100 to 1,000 years to decompose.
There is a potential moral problem in its production.
The continuous growth of the world’s population has aroused people’s concerns. For example, it is ethical to use all corn for the production of bioplastics instead of feeding the people in need.
It relies heavily on the use of genetically modified crops.
A complete discussion can be created around this topic.
But to name a few examples, the rise of a single culture, and the general concern about the lack of long-term testing, is a major flaw in the public domain.
Mixing with traditional plastics can pollute the recycling process.
Due to the different chemical properties of plastics labeled #1 and #6, PLA labeled #7 should be properly separated before the recycling process begins.
Pros and cons: decomposition.
Suppose you want to use biodegradable plastic to store food.
In the long run, using a plastic that (under the right conditions) will not be stored for centuries sounds amazing.
In the near future, you want your food to remain as fresh and delicious as possible.
This is especially a problem for food exports, because food must survive production, packaging, transportation, sales and final consumption.
PLA plasticwill behave in a fragile way unless it is mixed with less environmentally friendly polymers.
Compared with petroleum-based plastics, bioplastics such as polylactic acid lack strength and crystallinity.
All types of PLA are composed of lactic acid (C3H6O3).
Although the molecular formulas are the same, their difference lies in the orientation of the atoms in space.
They include poly-1-lactide (PLLA), poly-d-lactide (PLDA), and polydl-lactide (PDLLA).
Note that PLA is a nomenclature inconsistent with IUPAC because it is a polyester rather than a polyacid.
Food packaging industry: PLA is generally recognized as safe when it is used to store food.
Although lactic acid is released in contact with certain liquids, it has not been found that the concentration of lactic acid is high enough to be harmful to the human body.
Read more about PLA in the food industry and what you really need to know.
Healthcare and medical industry:PLA plasticis biocompatible, which means it can be used in devices in the human body with minimal inflammation and infection.
Therefore, due to its attractive source, it has been used in the production of biomedical and clinical applications for bone fixation devices such as screws, steel plates, surgical structures and meshes, and drug delivery systems.
A surprising addition is the possibility of tissue engineering.
Its biocompatibility and ability to dissolve in the body indicate that it has great prospects in solving problems such as tissue loss and organ failure.
Structural applications: PLA materials can be used in the construction industry, for example, foam insulation, fibers for carpets and furniture.
However, due to its characteristics and biological sensitivity, its application in this industry is limited.
Textile industry: Committed to the plastics industry, replacing non-renewable polyester fibers with bio-polylactic acid fibers.
Its advantages include breathability, lighter weight and recyclability.
Cosmetics industry: Consumers’ awareness of plastic pollution has prompted cosmetics and other industries to seek sustainable solutions to ensure product preservation.
The answer to this question depends entirely on where on earth it is asked.
In general, PLA plastic is sustainable.
It comes from renewable resources, absorbs carbon dioxide and converts it into glucose.
It will then be processed to obtain a product that is almost carbon-free.
After the PLA material is ready to be processed by the consumer, it can be biodegraded.
However, the last point depends on where its useful life ends.
The correct handling ofPLA plasticrequires very special conditions, and mixing with other plastics will affect the entire recycling process.
Waste PLA plastic needs to be sorted and sent to an industrial composting facility.
This means the environmental cost of transportation.
After that, the bioplastic will be heated to around 60°C and exposed to special microorganisms that will digest the material and decompose it.
However, many cities do not have the facilities to carry out this process.
Even if they do, PLA plastic needs a strict separation process, which cannot always be guaranteed.
Therefore, most PLA plastic waste will eventually be landfilled or enter the ocean.