Polylactic acid, also known as poly(lactic acid) or polylactide (PLA), is a

thermoplastic A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...

polyester Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natural ...

with backbone formula or , formally obtained by

condensation Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to ...

lactic acid Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as natu ...

with loss of water (hence its name). It can also be prepared by ring-opening polymerization of lactide , the cyclic dimer of the basic repeating unit. PLA has become a popular material due to it being economically produced from

renewable resource A renewable resource, also known as a flow resource, is a natural resource which will replenish to replace the portion resource depletion, depleted by usage and consumption, either through natural reproduction or other recurring processes in a ...

s. In 2021, PLA had the highest consumption volume of any bioplastic of the world, although it is still not a commodity polymer. Its widespread application has been hindered by numerous physical and processing shortcomings. PLA is the most widely used plastic filament material in

3D printing 3D printing or additive manufacturing is the Manufacturing, construction of a three-dimensional object from a computer-aided design, CAD model or a digital 3D modeling, 3D model. It can be done in a variety of processes in which material is ...

. Its low melting point, high strength, low thermal expansion, good layer adhesion, and high heat resistance when annealed make it an ideal material for this purpose. Without annealing, however, PLA has the lowest heat resistance of the common 3D printing plastics. Although the name "polylactic acid" is widely used, it does not comply with

IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...

standard nomenclature, which is "poly(lactic acid)". The name "polylactic acid" is potentially ambiguous or confusing, because PLA is not a polyacid ( polyelectrolyte), but rather a polyester.

Chemical properties

Synthesis

The monomer is typically made from fermented plant starch such as from

corn Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...

cassava ''Manihot esculenta'', common name, commonly called cassava (), manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America. Although a perennial plant, cassava is extensively ...

sugarcane Sugarcane or sugar cane is a species of (often hybrid) tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with ...

sugar beet pulp Beet pulp is a byproduct from the processing of sugar beet which is used as fodder for horses and other livestock. Beet pulp is the fibrous material left over after the sugar is extracted from sugar beets. It is supplied either as dried flakes or ...

. Several industrial routes afford usable (i.e. high molecular weight) PLA. Two main monomers are used:

, and the cyclic di-ester, lactide. The most common route to PLA is the ring-opening

polymerization In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer, monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are ...

of lactide with various metal

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

s (typically

tin octoate Tin(II) 2-ethylhexanoate or tin(II) octoate or stannous octoate (Sn(Oct)2) is a compound of tin. Produced by the reaction of tin(II) oxide and 2-ethylhexanoic acid, it is a clear colorless liquid at room temperature, though often appears yellow du ...

) in solution or as a suspension. The metal-catalyzed reaction tends to cause racemization of the PLA, reducing its stereoregularity compared to the starting material (usually corn starch). The direct condensation of lactic acid monomers can also be used to produce PLA. This process needs to be carried out at less than 200 °C; above that temperature, the entropically favored lactide monomer is generated. This reaction generates one equivalent of water for every condensation ( esterification) step. The condensation reaction is reversible and subject to equilibrium, so removal of water is required to generate high molecular weight species. Water removal by application of a vacuum or by

azeotropic distillation In chemistry, azeotropic distillation is any of a range of techniques used to break an azeotrope in distillation. In chemical engineering, ''azeotropic distillation'' usually refers to the specific technique of adding another component to genera ...

is required to drive the reaction toward polycondensation. Molecular weights of 130 kDa can be obtained this way. Even higher molecular weights can be attained by carefully crystallizing the crude polymer from the melt. Carboxylic acid and alcohol end groups are thus concentrated in the amorphous region of the solid polymer, and so they can react. Molecular weights of 128–152 kDa are obtainable thus. : PLA from lactic acid & lactide

Another method devised is by contacting lactic acid with a zeolite. This condensation reaction is a one-step process, and runs about 100 °C lower in temperature.

Stereoisomers

Due to the chiral nature of lactic acid, several distinct forms of polylactide exist: poly-L-lactide (PLLA) is the product resulting from polymerization of L,L-lactide (also known as L-lactide). Progress in biotechnology has resulted in the development of commercial production of the D enantiomer form. Polymerization of a

racemic mixture In chemistry, a racemic mixture, or racemate (), is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule or salt. Racemic mixtures are rare in nature, but many compounds are produced industrially as racemates. ...

of L- and D-lactides usually leads to the synthesis of poly-DL-lactide (PDLLA), which is amorphous. Use of stereospecific catalysts can lead to heterotactic PLA which has been found to show crystallinity. The degree of crystallinity, and hence many important properties, is largely controlled by the ratio of D to L enantiomers used, and to a lesser extent on the type of catalyst used. Apart from lactic acid and lactide, lactic acid ''O''-carboxyanhydride ("lac-OCA"), a five-membered cyclic compound has been used academically as well. This compound is more reactive than lactide, because its polymerization is driven by the loss of one equivalent of carbon dioxide per equivalent of lactic acid. Water is not a co-product. The direct biosynthesis of PLA, in a manner similar to production of poly(hydroxyalkanoate)s, has been reported.

Physical and mechanical properties

PLA polymers range from amorphous glassy polymer to semi-crystalline and highly crystalline polymer with a

glass transition The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle "glassy" state into a viscous or rubb ...

60–65 °C, a melting temperature 130-180 °C, and a

Young's modulus Young's modulus E, the Young modulus, or the modulus of elasticity in tension or compression (i.e., negative tension), is a mechanical property that measures the tensile or compressive stiffness of a solid material when the force is applied leng ...

2.7–16 GPa. Heat-resistant PLA can withstand temperatures of 110 °C. The basic mechanical properties of PLA are between those of

polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a ...

and PET. The melting temperature of PLLA can be increased by 40–50 °C and its heat deflection temperature can be increased from approximately 60 °C to up to 190 °C by physically blending the polymer with PDLA (poly-D-lactide). PDLA and PLLA form a highly regular stereocomplex with increased crystallinity. The temperature stability is maximised when a 1:1 blend is used, but even at lower concentrations of 3–10% of PDLA, there is still a substantial improvement. In the latter case, PDLA acts as a nucleating agent, thereby increasing the crystallization rate.

Biodegradation Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegrada ...

of PDLA is slower than for PLA due to the higher crystallinity of PDLA. The flexural modulus of PLA is higher than polystyrene and PLA has good heat sealability. Several technologies such as annealing, adding

nucleating In thermodynamics, nucleation is the first step in the formation of either a new thermodynamic phase or structure via self-assembly or self-organization within a substance or mixture. Nucleation is typically defined to be the process that determ ...

agents, forming composites with fibers or nano-particles, chain extending and introducing crosslink structures have been used to enhance the mechanical properties of PLA polymers. Polylactic acid can be processed like most thermoplastics into

fiber Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...

(for example, using conventional melt spinning processes) and film. PLA has similar mechanical properties to

PETE Pete or Petes or ''variation'', may refer to: People * Pete (given name) * Pete (nickname) * Pete (surname) Fictional characters * Pete (Disney), a cartoon character in the ''Mickey Mouse'' universe * Pete the Pup (a.k.a. 'Petey'), a character ...

polymer, but has a significantly lower maximum continuous use temperature. Racemic PLA and pure PLLA have low

temperatures, making them undesirable because of low strength and melting point. A stereocomplex of PDLA and PLLA has a higher glass transition temperature, lending it more mechanical strength. The high surface energy of PLA results in good printability, making it widely used in 3D printing. The tensile strength for 3D printed PLA was previously determined.

Solvents

PLA is soluble in a range of organic solvents. Ethyl acetate is widely used because of its ease of access and low risk. It is useful in 3D printers for cleaning the extruder heads and for removing PLA supports. Other safe solvents include

propylene carbonate Propylene carbonate (often abbreviated PC) is an organic compound with the formula C4H6O3. It is a cyclic carbonate ester derived from propylene glycol. This colorless and odorless liquid is useful as a polar, aprotic solvent. Propylene carbonat ...

, which is safer than ethyl acetate but is difficult to purchase commercially.

Pyridine Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a d ...

can be used, but it has a distinct fish odor and is less safe than ethyl acetate. PLA is also soluble in hot

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...

tetrahydrofuran Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water-miscible organic liquid with low viscosity. It is ma ...

, and

dioxane 1,4-Dioxane () is a heterocyclic organic compound, classified as an ether. It is a colorless liquid with a faint sweet odor similar to that of diethyl ether. The compound is often called simply dioxane because the other dioxane isomers ( 1,2- ...

Fabrication

PLA objects can be fabricated by 3D printing, casting,

injection moulding Injection moulding (U.S. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals (for ...

extrusion Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex c ...

, machining, and solvent welding. Bobina PLA

PLA is used as a feedstock material in desktop fused filament fabrication by

3D printers 3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer co ...

, such as RepRap printers. The boiling point of ethyl acetate is low enough to smooth PLA surfaces in a vapor chamber, similar to using acetone vapor to smooth ABS. PLA can be solvent welded using

dichloromethane Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible with ...

Acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscib ...

also softens the surface of PLA, making it sticky without dissolving it, for welding to another PLA surface. PLA-printed solids can be encased in plaster-like moulding materials, then burned out in a furnace, so that the resulting void can be filled with molten metal. This is known as "lost PLA casting", a type of

investment casting Investment casting is an industrial process based on lost-wax casting, one of the oldest known metal-forming techniques. The term "lost-wax casting" can also refer to modern investment casting processes. Investment casting has been used in vari ...

Applications

Consumer goods

PLA is used in a large variety of consumer products such as

disposable tableware Disposable tableware includes all disposable tableware like * disposable cups made of paper, plastic, coated paper, * plates *tablecloths, * placemats *plastic cutlery, *paper napkins, etc. These products are prevalent in fast food restaurants, ...

cutlery Cutlery (also referred to as silverware, flatware, or tableware), includes any hand implement used in preparing, serving, and especially eating food in Western culture. A person who makes or sells cutlery is called a cutler. The city of Sheffie ...

, housings for kitchen appliances and electronics such as laptops and handheld devices, and microwavable trays. (However, PLA is not suitable for microwavable containers because of its low glass transition temperature.) It is used for compost bags, food packaging and loose-fill packaging material that is cast, injection molded, or spun. In the form of a film, it shrinks upon heating, allowing it to be used in shrink tunnels. In the form of fibers, it is used for monofilament fishing line and netting. In the form of

nonwoven fabric Nonwoven fabric is a fabric-like material made from staple fibre (short) and long fibres (continuous long), bonded together by chemical, mechanical, heat or solvent treatment. The term is used in the textile manufacturing industry to denote fabri ...

s, it is used for

upholstery Upholstery is the work of providing furniture, especially seats, with padding, springs, webbing, and fabric or leather covers. The word also refers to the materials used to upholster something. ''Upholstery'' comes from the Middle English word ...

, disposable garments,

awning An awning or overhang is a secondary covering attached to the exterior wall of a building. It is typically composed of canvas woven of acrylic, cotton or polyester yarn, or vinyl laminated to polyester fabric that is stretched tightly over a lig ...

s, feminine hygiene products, and diapers. PLA has applications in engineering plastics, where the stereocomplex is blended with a rubber-like polymer such as ABS. Such blends have good form stability and visual transparency, making them useful in low-end packaging applications. PLA is used for automotive parts such as floor mats, panels, and covers. Its heat resistance and durability are inferior to the widely used

polypropylene Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene. Polypropylene belongs to the group of polyolefins and ...

(PP), but its properties are improved by means such as capping of the end groups to reduce hydrolysis.

Agricultural

In the form of fibers, PLA is used for monofilament fishing line and netting for vegetation and weed prevention. It is used for sandbags, planting pots, binding tape and ropes .

Medical

PLA can degrade into innocuous lactic acid, making it suitable for use as medical implants in the form of anchors, screws, plates, pins, rods, and mesh. Depending on the type used, it breaks down inside the body within 6 months to 2 years. This gradual degradation is desirable for a support structure, because it gradually transfers the load to the body (e.g., to the bone) as that area heals. The strength characteristics of PLA and PLLA implants are well documented. Thanks to its bio-compatibility and biodegradability, PLA found interest as a polymeric scaffold for drug delivery purposes. The composite blend of poly(L-lactide-''co''-D,L-lactide) (PLDLLA) with tricalcium phosphate (TCP) is used as PLDLLA/TCP scaffolds for bone engineering. Poly-L-lactic acid (PLLA) is the main ingredient in

Sculptra Sculptra, , is a proprietary formulation of poly-L-lactic acid (PLLA) that is an FDA-approved dermal filler manufactured by Dermik Laboratories, which conducts the American business of Aventis Dermatology, the global dermatology unit of Aventis (of ...

, a facial volume enhancer used for treating

lipoatrophy Lipoatrophy is the term describing the localized loss of fat tissue. This may occur as a result of subcutaneous injections of insulin in the treatment of diabetes, from the use of human growth hormone or from subcutaneous injections of copaxone use ...

of the cheeks. PLLA is used to stimulate collagen synthesis in fibroblasts via foreign body reaction in the presence of macrophages. Macrophages act as a stimulant in secretion of cytokines and mediators such as

TGF-β Transforming growth factor beta (TGF-β) is a multifunctional cytokine belonging to the transforming growth factor superfamily that includes three different mammalian isoforms (TGF-β 1 to 3, HGNC symbols TGFB1, TGFB2, TGFB3) and many other sign ...

, which stimulate the fibroblast to secrete collagen into the surrounding tissue. Therefore, PLLA has potential applications in the dermatological studies. PLLA is under investigation as a scaffold that can generate a small amount of

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...

via the piezoelectric effect that stimulates the growth of mechanically robust

cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...

in multiple animal models. File:Mulch Film made of PLA-Blend Bio-Flex.jpg, Mulch film made of PLA-blend "bio-flex" File:Cmglee PLA cups.jpg, Biodegradable PLA cups File:Teebeutel Polylactid 2009.jpg, Tea bags made of PLA. Peppermint tea is enclosed. File:3D printing of PLA-CNT microcoil.webm, 3D printing of a

microcoil A microcoil is a tiny electrical conductor such as a wire in the shape of a spiral or helix which could be a solenoid or a planar structure. Uses NMR spectroscopy and micro-MRI One field where these are found is nuclear magnetic resonance ( ...

using a conductive mixture of polylactide and

carbon nanotube A scanning tunneling microscopy image of a single-walled carbon nanotube Rotating single-walled zigzag carbon nanotube A carbon nanotube (CNT) is a tube made of carbon with diameters typically measured in nanometers. ''Single-wall carbon na ...

s. File:3D Printed Macrognathism.jpg, 3D printed human skull with data from

computed tomography A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...

. Transparent PLA.

Degradation

PLA is degraded abiotically by three mechanisms: #

Hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

: The ester groups of the main chain are cleaved, thus reducing molecular weight. # Thermal decomposition: A complex phenomenon leading to the appearance of different compounds such as lighter molecules and linear and cyclic oligomers with different ''Mw'', and lactide. # Photodegradation: UV radiation induces degradation. This is a factor mainly where PLA is exposed to sunlight in its applications in plasticulture, packaging containers and films. The hydrolytic reaction is: -COO + H2O -> - COOH + -OH- The degradation rate is very slow in ambient temperatures. A 2017 study found that at 25 °C in seawater, PLA showed no loss of mass over a year, but the study did not measure breakdown of the polymer chains or water absorption. As a result, it degrades poorly in

landfill A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials. Landfill is the oldest and most common form of waste disposal, although the systematic burial of the waste ...

s and household composts, but is effectively digested in hotter industrial composts, usually degrading best at temperatures of over . Pure PLA foams are selectively hydrolysed in Dulbecco's modified Eagle's medium (DMEM) supplemented with fetal bovine serum (FBS) (a solution mimicking body fluid). After 30 days of submersion in DMEM+FBS, a PLLA scaffold lost about 20% of its weight. PLA samples of various molecular weights were degraded into

methyl lactate Methyl lactate, also known as lactic acid methyl ester, is the organic compound with the formula CH3CH(OH)CO2CH3. It is the methyl ester of lactic acid. A colorless liquid, it is the simplest chiral ester. Being naturally derived, it is readily ...

(a green solvent) by using a metal complex catalyst. PLA can also be degraded by some bacteria, such as ''

Amycolatopsis ''Amycolatopsis'' is a genus of high GC-content bacteria within the family Pseudonocardiaceae. The genus is known for producing many types of antibiotics, including * Epoxyquinomicin, related to ''Amycolatopsis sulphurea'', are a class of weak ...

'' and '' Saccharothrix''. A purified protease from ''

'' sp.,

PLA depolymerase PLA may refer to: Organizations Politics and military * People's Liberation Army, the armed forces of China and of the ruling Chinese Communist Party * People's Liberation Army (disambiguation) ** Irish National Liberation Army, formerly called th ...

, can also degrade PLA. Enzymes such as pronase and most effectively proteinase K from '' Tritirachium album'' degrade PLA.

End of life

Four possible end-of-life scenarios are the most common: #

Recycling Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...

: which can be either chemical or mechanical. Currently, the SPI resin identification code 7 ("others") is applicable for PLA. In Belgium, Galactic started the first pilot unit to chemically recycle PLA (Loopla). Unlike mechanical recycling, waste material can hold various contaminants. Polylactic acid can be chemically recycled to monomer by thermal depolymerization or hydrolysis. When purified, the monomer can be used for the manufacturing of virgin PLA with no loss of original properties ( cradle-to-cradle recycling). End-of-life PLA can be chemically recycled to

by transesterification. #

Compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plant, food waste, recycling organic materials and manure. The resulting m ...

ing: PLA is biodegradable under industrial composting conditions, starting with chemical hydrolysis process, followed by microbial digestion, to ultimately degrade the PLA. Under industrial composting conditions (), PLA can partly (about half) decompose into water and carbon dioxide in 60 days, after which the remainder decomposes much more slowly, with the rate depending on the material's degree of crystallinity. Environments without the necessary conditions will see very slow decomposition akin to that of non-bioplastics, not fully decomposing for hundreds or thousands of years. # Incineration: PLA can be

incinerated Incineration is a waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities. Incineration and other high ...

without producing chlorine-containing chemicals or heavy metals because it contains only

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

, and

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

atoms. Since it does not contain chlorine it does not produce

dioxins Dioxin may refer to: * 1,2-Dioxin or 1,4-Dioxin, two unsaturated heterocyclic 6-membered rings where two carbon atoms have been replaced by oxygen atoms, giving the molecular formula C4H4O2 *Dibenzo-1,4-dioxin, the parent compound also known as ...

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

during incineration. PLA can be combusted with no remaining residue. This and other results suggest that incineration is an environmentally friendly disposal of waste PLA. #

Landfill A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials. Landfill is the oldest and most common form of waste disposal, although the systematic burial of the waste ...

: the least preferable option is landfilling because PLA degrades very slowly in ambient temperatures, often as slowly as other plastics.

References

External links

"Your plastic pal" , ''The Economist''
{{Use dmy dates, date=January 2018 Biodegradable plastics Bioplastics Polyesters Synthetic fibers Transparent materials Thermoplastics Articles containing video clips Fused filament fabrication