Polylactic Acid (PLA, Polylactide)
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PLA is a thermoplastic, further classified as a polyester plastic. It has the highest heat capacity and the lowest thermal conductivity relative to other polyester plastics. The graph bars on the material properties cards below compare PLA to: polyester plastics (top), all thermoplastics (middle), and the entire database (bottom). The length of each bar shows the given value as a % of the largest value in the relevant set.
Mechanical Properties
Elastic (Young's, Tensile) Modulus
3.5 GPa 0.51 x 106 psi
Elongation at Break
6.0 %
Flexural Modulus
4.0 GPa 0.58 x 106 psi
Flexural Strength
80 MPa 12 x 103 psi
Shear Modulus
2.4 GPa 0.35 x 106 psi
Tensile Strength: Ultimate (UTS)
50 MPa 7.3 x 103 psi
Other Material Properties
Density
1.3 g/cm3 78 lb/ft3
Glass Transition Temperature
60 °C 140 °F
Heat Deflection Temperature At 455 kPa (66 psi)
65 °C 150 °F
Melting Onset (Solidus)
160 °C 320 °F
Specific Heat Capacity
1800 J/kg-K 0.43 BTU/lb-°F
Thermal Conductivity
0.13 W/m-K 0.075 BTU/h-ft-°F
Common Calculations
Stiffness to Weight: Axial
1.6 points
Stiffness to Weight: Bending
40 points
Strength to Weight: Axial
11 points
Strength to Weight: Bending
24 points
Thermal Diffusivity
0.058 m2/s
Followup Questions
Further Reading
SPI Plastics Engineering Handbook of the Society of the Plastics Industry, Inc., 5th ed., Michael L. Berins (editor), 2000
Modern Plastics Handbook, Charles A. Harper (editor), 1999
Plastics Materials, 7th ed., J. A. Brydson, 1999