May. 19, 2025
PLA is a type of polyester made from fermented plant starch from corn, cassava, maize, sugarcane or sugar beet pulp. The sugar in these renewable materials are fermented and turned into lactic acid, when is then made into polylactic acid, or PLA.
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There is more detailed information on PLA production methods below.
The material properties of PLA makes it suitable for the manufacture of plastic film, bottles and biodegradable medical devices, including screws, pins, plates and rods that are designed to biodegrade within 6 to 12 months).
PLA can be used as a shrink-wrap material since it constricts under heat. This ease of melting also makes polylactic acid suitable for 3D printing applications.
However, many types of PLA have a low glass transition temperature, making them unsuitable for making plastic cups designed to hold hot liquids.
PLA production uses 65% less energy than producing conventional plastics and generates 68% fewer greenhouse gases and contains no toxins. It can be also remain environmentally friendly should the correct end-of-life scenario be followed.
However, the rate of degradation is very slow in ambient temperatures, with a study showing that there was no degradation seen in over a year of the material being submerged in seawater at 25°C.
However, PLA can be degraded by hydrolysis, thermal degradation or photodegradation:
There are currently four common end-of-life scenarios for PLA:
This is either chemical or mechanical. Waste material can hold contaminants, but ployactic acid can be chemically recycled using thermal depolymerisation or hydrolysis to create a monomer that can then be manufactured into virgin PLA. PLA can also be chemically recycled using transesterification to create methyl lactate.
Industrial composting conditions allow for chemical hydrolysis followed by microbial digestion to degrade the PLA.
End-of-life PLA can be incinerated, creating 19.5 MJ/kg (8,368 btu/lb) of energy and leaving no residue.
While PLA can go to landfill, this is the least environmentally friendly option, due to the slow degradation rates of the material in ambient temperatures.
Due to the nature of lactic acid, there are several distinct forms of polyactide. These include poly-L-lactide (PLLA) which comes from the polymerization of L,L-lactide (also known as L-lactide).
In addition, while PLA can be produced from different biomass materials, such as corn starch or sugar cane, it can also be enhanced by adding other materials to provide different properties. This is particularly true with PLA filaments where the additional materials allow 3D printed PLA to be used in different ways.
There are many different PLA blends available, although adding materials to PLA can make 3D printing more difficult and even reduce the properties of PLA. Using blends can also mean that you need to alter the temperature required to melt the material while printing.
PLA is mixed with woods such as bamboo, cedar, coconut wood, cork, pine, or walnut. This can, for example, be used to give PLA printed furniture a natural-looking appearance.
Mixing PLA with metals such as brass, bronze, copper, iron and steel can make printed parts stronger and glossy.
PLA can also be mixed with other materials and substances, including carbon fibre, conductive carbon and even beer or coffee (to add a scent to printed items). PLA filaments can also be given colour-changing properties.
PLA is soluble in solvents including dioxane, hot benzene, and tetrahydrofuran. The physical and mechanical properties differ according to the exact type of polymer, ranging from an amorphous glassy polymer to a semi or highly crystalline polymer with a glass transition of 60–65 °C, a melting temperature 130-180 °C, and a tensile modulus of 2.7–16 GPa.
Heat resistant PLA can withstand temperatures of 110 °C, and the melting temperature can be increased by 40–50 °C and the heat deflection temperature can be increased from around 60 °C to as much as 190 °C by physically blending the polymer with PDLA (poly-D-lactide).
Annealing, adding nucleating agents or forming composites with other materials can all change the mechanical properties of PLA. However, the basic mechanical properties of PLA range between those of polystyrene and PET, with similar properties to PET but a lower maximum continuous use temperature.
The high surface energy of PLA makes it ideal for 3D printing. PLA can also be solvent welded using dichloromethane, while acetone softens the surface of the material, making it sticky without dissolving it so it can be welded to another PLA surface. Ethylacetate can be used as an organic solvent, dissolving PLA and making it a good solution for removing PLA printing supports or cleaning 3D printing extruder heads. Propylene carbonate and pyridine can also be used as a solvent, but are less favourable than ethylacetate and propylene carbonate, being less safe in the first instance and emitting a distinct bad fish odour in the second.
Here are the general properties of PLA:
PLA provides several advantages over other materials, including:
There are, however, some disadvantages with using PLA, including:
There are several industrial ways to produce usable PLA with a high molecular rate. Lactic acid and the cyclic di-ester, lactide are the two main monomers used for this.
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The most common method of creating PLA is ring-opening polymerisation of lactide with various metal catalysts (typically tin octoate) either in a solution or as a suspension. The metal-catalysed reaction tends to lead to recemisation of the PLA, which reduces stereoregularity when compared to the biomass starting material.
It is also possible to produce PLA through the direct condensation of lactic acid monomers. This process is carried out at temperatures under 200 °C, at which point an entropically favoured lactide monomer is generated. This process generates water equivalent to each esterification step. The water needs to be removed either by using a vacuum or through azeotropic distillation to promote polycondensation and attain a high molecular rate. Even higher molecular rates can be achieved by crystallising the crude polymer from the melt. This concentrates carbolyxic acid and alcohol end groups in the amorphous region of the solid polymer, reacting to achieve molecular weights of 128–152 kDa.
By polymerising a racemic mixture of L- and D-lactides, it is possible to synthesise the amorphous poly-DL-lactide (PDLLA). Stereospecific catalysts can lead to heterotactic PLA, that has been known to show crystallinity. The degree of this crystallinity is controlled by the ratio of D to L enantiomers that are used, as well as by the type of catalyst that is used. The five-membered cyclic compound lactic acid O-carboxyanhydride (lac-OCA) has also been used in academic surroundings instead of lactic acid and lactide. This compound doesn’t produce water as a co-product and is more reactive than lactide. PLA has also been directly biosynthesised while lactic acid has also been contacted with a zeolite, creating a one-step process that takes place at a temperature that is around 100 °C lower.
PLA has a number of common uses, including for medical and food purposes. It is also widely used as a 3D printing feedstock for desktop fused filament fabrication 3D printers. PLA is popular for 3D printing as it can easily be sanded, painted or post processed. A user friendly material, this plastic works with low extrusion temperatures and there is no need for a heated bed, printer chamber or reinforced nozzle. Another benefit is that PLA behaves better than many tougher plastics and also doesn’t release fumes or bad odours. Storage is easy and it can be produced in a variety of colours and as the base for a range of composites with additional properties (see above).
Because PLA can degrade into lactic acid, it can be used for medical implants such as anchors, screws, plates, pins, rods or as a mesh. It breaks down in between 6 months and 2 years, depending on the exact type of material used. This means that these products can gradually transfer a load from a PLA support structure to the body as it heals.
PLA, created with injection moulding, casting or by being spun, is also used as a decomposable packaging material, film or for cups and bags. It is used for compost bags, food packaging, disposable tableware, and loose fill packaging. As a fibre or nonwoven fabric, PLA is used for upholstery, disposable clothing, feminine hygiene products and nappies.
Made from a recyclable and renewable resource, PLA has a lot of positives for the future, plus with rising oil prices, a corn-based plastic has financial benefits too. For all of these positives the low melting point of PLA compared to plastics like PET means that it has not been picked up for as many applications as of yet.
The cost of PLA production has also reduced over the decades, but care needs to be taken to decompose this material, which needs special composting in facilities that can heat the material to 140°C degrees for ten days. However, while this requires a plant to achieve, it is by far more preferable to sending used PLA to landfill, where it is estimated it would take as long as 100 to 1,000 years to break down.
While PLA is not quite a miracle substance, the lack of fossil fuels and lower air pollution in production mean it certainly has a place in the future of materials.
Used in a variety of applications, PLA has many advantages over other plastics – including environmentally. Widely used for 3D printing and able to be used as part of a composite, PLA is also used in the food and medical industries.
In the last decade, interest in biodegradable plastics and biodegradable packaging has skyrocketed. Indeed, when more than 67 million kilos of packaging waste is generated in the EU alone, and a substantial amount turns into everyday waste. Food packaging, in particular, is one of the most common sources of packaging waste in the UK.
Biodegradable packaging – sometimes referred to more generally as ‘green packaging’ – has often had an exceptionally positive reception among the general public. This is not surprising, because, more than ever, we need to try and reduce our carbon footprint as much as possible. However, there is still much misinformation around the topic. In this post, we aim to explain the biggest advantages and disadvantages around biodegradable shrink wrap in particular.
According to the ISO (the International Organization for Standardization), biodegradation of plastic waste refers to degradation caused by biological activity, such as enzymatic action, leading to a significant change in the material’s chemical structure. Something has ‘biodegraded’ when about 90% of the maximum level of biodegradation has been reached.
Biodegradability is an end of life option that allows one to harness the power of microorganisms present in the selected disposal environment to completely remove biodegradable plastic products from the environmental compartment in a timely, safe and efficient manner. Biodegradation that can take place in water is sometimes referred to as hydro-degradable material.
Typically, biodegradation has to take place as a result of microorganisms found in either water or carbon dioxide. The nature of the environment, the degree of microbial utilisation (biodegradation), and the time frame in which biodegradation occurs are specified in an ASTM (formerly the American Society for Testing and Materials) standard. When we commonly refer to biodegradable plastics, we tend to be talking about things that biodegrade in a matter of years – some petroleum-based plastics technically will biodegrade over much longer time frames but are hardly environmentally friendly.
The most common types of biodegradable plastics are PLA and PCL – polylactic acid and polycaprolactone respectively. PCL’s low melting point (60 degrees Celsius) makes it unsuitable as a shrink wrap material. By contrast, PLA is not only biodegradable but also a bio-based plastic, typically made from vegetables such as corn that are transformed to lactic acid before polymerisation. You can read more about the varieties of bioplastic in our past blog post.
As we have established, PLA is one of the more popular kinds of biodegradable shrink wrap. This means that we can significantly mitigate the environmental impact of said shrink wrap in the environment, something which adds value to any business’ offerings. To evaluate biodegradable shrink wrap, we’ll take PLA as an example and go through its supposed strengths and its weaknesses.
However, to biodegrade, PLA requires a laundry list of conditions to effectively break down, specifically a temperature of over 140 degrees, high humidity, plenty of oxygen and a 2/3 cocktail of organic substrate mixed alongside PLA. Collectively, these are absent in any scenario outside of industrial composting facilities. This means that, without proper disposal, PLA plastic will sit in landfills and will not degrade. Furthermore, the high costs of proper disposal can come as a big surprise to many businesses.
Secondly, PLA is a bio-based plastic. As PLA is produced from polylactic acid, which in turn is produced from vegetables like sugarcane or corn. This reduces one’s reliance on petroleum-based products, which makes PLA seem environmentally friendly.
However, as we’ve talked about before on resource minimisation, using bio-based plastics can give you a false sense of security. Limited resources that have to be spent producing bio-based PLA could be spent in the food production or water supply, and the tools used to convert vegetables into PLA still have a significant environmental footprint.
Thirdly, PLA is a compostable plastic. Compostable plastics are a new generation of plastics which are degradable through composting. They are generally derived from renewable raw materials like starch, cellulose, soy protein, or lactic acid. They are not hazardous in production and decompose back to carbon dioxide, water and biomass when composted. Counterintuitively, some compostable plastics may not be derived from renewable materials at all but instead derived from petroleum or made by bacteria through a process of microbial fermentation.
However, PLA is not an easily compostable plastic. Compostability requires a commercial composting facility, where higher temperatures can be achieved, and total composting is realised in 90 to 180 days. As such, unless you send your plastic to a dedicated composting facility, it is unlikely to compost. Indeed, recent investigations at Berkeley show that compostable plastics don’t even often end up composted. PLA plastic will last as long as any non-compostable alternative if not properly degraded, meaning your environmental footprint might be the same.
There is a lot of talk in the industry in the last few years about the development of oxo-biodegradable, sometimes called oxo-degradable, plastics. Oxo-biodegradation proposes that, indeed, the plastic progresses from degradation to being entirely assimilated by the microbial populations in the disposal infrastructure, but this requires complete decomposition within a reasonably short period under customary methods of disposal.
Current technology in display shrink film offers only oxo-biodegradable material; unfortunately, there are no compostable resins available that would work in shrink wrap. Should any high-quality shrink film come to market, rest assured we would be the first to offer it.
Kempner is consistently at the forefront of sourcing the most technologically advanced films. From our polyolefin shrink wrap to our PVC shrink wrap film, we are known for the most sophisticated shrink films in the lowest thicknesses yet with unbeatable performance. However, at the moment, all current thinking concerns reuse and recycling as the best ways to minimise our carbon footprint. That’s why Kempner remains focussed on resource minimisation to reduce the environmental impact of our films.
If you are looking for shrink wrapping machinery or a shrink wrap provider for your business, get in touch, and we would be happy to provide you with our expertise. Call us at 020 or leave us a message in our enquiry box on the right-hand side of this webpage to get in touch.
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