PLA (Polylactic Acid)

polymer

semi-crystalline bio-derived thermoplastic polyester

Polylactic acidPolylactidePLA+PolyLite PLAUltimaker PLAESUN PLABio-PLA

PLA (Polylactic Acid) 3D printed component

Density

1.24 g/cm³

UTS (FDM as-built (XY))

50–65 MPa

Elongation (FDM as-built (XY))

3.0–10.0 %

Elastic modulus

3–4 GPa

Glass transition (Tg)

55–65 °C

Mechanical & thermal properties — 3 conditions

Property	FDM as-built (XY)	FDM as-built (Z — upright)	FDM annealed (55°C / 1 h, XY)
Elastic modulus	3–4 GPa	—	3–4 GPa
Ultimate tensile strength	50–65 MPa	35–45 MPa	—
Elongation at break	3.0–10.0 %	1.0–6.0 %	—
Density	1.22–1.26 g/cm³	—	—
Glass transition (Tg)	55–65 °C

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Engineering considerations

Heat resistance is the decisive selection criterion. If the part will ever exceed 45°C under load (sun exposure, near electronics, automotive interior) — do not use standard PLA. Consider PETG (Tg ~80°C), ABS (Tg ~105°C), or ASA instead.
Orientation strategy: maximise load-bearing in XY direction. Z-direction strength is 70–80% of XY. For critical cross-sections, flat-print with load in the horizontal plane. Wall thickness minimum 1.2 mm for structural parts; 0.8 mm possible for cosmetic features.
Infill pattern and density drive structural properties more than material choice for FDM. At 20% gyroid infill, strength is ~30–40% of solid. Use 100% rectilinear infill in load-bearing cross-sections. Model hollow bodies with thick walls rather than high-infill solids for optimal stiffness-to-weight.
Moisture management: PLA absorbs moisture during storage (Hygroscopic). Wet filament causes bubbles, stringing, poor layer adhesion, and reduced mechanical properties. Dry at 45–50°C for 4h before printing if stored >2 weeks unsealed. Vacuum-seal with desiccant for long-term storage.
Post-processing: PLA cannot be smoothed with acetone (unlike ABS). Ethyl acetate vapour works but is flammable and requires extraction. For smooth surfaces: sand through 220→400→800→1200 grit then prime. Polyurethane or epoxy coating provides UV protection and sealing.
Biodegradability in context: PLA only biodegrades in industrial composting facilities (55°C+, specific microorganism mix). It does not degrade in landfill, ocean, or home compost at a meaningful rate. The bio-derived carbon content reduces lifecycle CO₂ but part longevity is not guaranteed for outdoor applications.
PLA+ grades: many suppliers offer 'PLA+' formulations with toughening additives (PBAT, TPU blends) that significantly increase impact resistance and elongation. These are proprietary blends — verify properties with supplier datasheet. Impact resistance can be 3–5× standard PLA at modest cost increase.

Advantages

Easiest FDM material to print: sticks to build plate, minimal warping, no heated chamber needed, low odour
Highest stiffness of common FDM polymers (~3.5 GPa): stiffer than PETG (~2.2 GPa) and ABS (~2.1 GPa)
Bio-derived from renewable feedstock (corn starch, sugarcane): lower carbon footprint per kg vs petroleum-based polymers
Industrially compostable (EN 13432 certified grades): meets EU single-use plastics legislation for some applications
Wide filament ecosystem: available in every colour, diameter, and specialty blend (PLA+, metal-fill, wood-fill, carbon-fill)
Dimensionally stable: low shrinkage during printing — easier to achieve dimensional accuracy than ABS
Lowest cost of common FDM filaments — commodity grades available from ~£15–25/kg
Good optical clarity in transparent grades; excellent surface finish achievable with sanding and painting

Limitations

Very low heat resistance: HDT ~50–60°C at 0.45 MPa. Parts permanently deform in hot cars, near heating vents, or in direct sunlight
Brittle: lowest impact resistance of the common FDM polymers. Snap-fits and impact-loaded parts require PETG or ABS instead
UV degradation: PLA yellows and loses toughness with prolonged UV exposure. Not suitable for long-term outdoor use without UV-stabiliser coating
Hygroscopic: absorbs moisture in storage, causing print quality problems (bubbles, stringing). Store in sealed containers with desiccant
Not suitable for powder-bed fusion (SLS/MJF): insufficient thermal stability and unsuitable crystallisation kinetics
Biodegrades in industrial composting conditions (not home compost) — may be a limitation for long-life product applications
Low chemical resistance: attacked by ketones (acetone) and some esters; not suitable for chemical-contact applications
Post-processing: acetone smoothing does NOT work on PLA (unlike ABS). Requires sanding or vapour smoothing with ethyl acetate

Typical applications

Visual prototypes, concept models, and display partsLow-stress functional parts at room temperatureEducational and hobby applications — most widely used consumer FDM materialPackaging prototypes and ergonomic handlesMedical device non-implantable mockups and anatomical modelsArchitectural models and scale modelsJigs and fixtures for room-temperature assembly operationsConsumer product housings and enclosures not exposed to heatEco-packaging: compostable in industrial compost facilities

PLA (Polylactic Acid)

Mechanical & thermal properties — 3 conditions

Engineering considerations

Advantages

Limitations

Typical applications

Industries

Standards & certifications

Compatible AM processes (1)

Other polymer materials

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