Polyhydroxybutyrate (PHB)
PHB is a thermoplastic, further classified as a polyester plastic. It has a moderately low tensile strength among the polyester plastics in the database. The graph bars on the material properties cards below compare PHB to: polyester plastics (top), all thermoplastics (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Elastic (Young's, Tensile) Modulus
1.3 GPa 0.19 x 106 psi
Elongation at Break
7.5 %
Flexural Strength
20 MPa 2.9 x 103 psi
Tensile Strength: Ultimate (UTS)
30 MPa 4.4 x 103 psi
Thermal Properties
Heat Deflection Temperature At 1.82 MPa (264 psi)
60 °C 140 °F
Maximum Temperature: Mechanical
120 °C 250 °F
Melting Onset (Solidus)
180 °C 350 °F
Vicat Softening Temperature
58 °C 140 °F
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 Hz
3.0
Electrical Resistivity Order of Magnitude
14 10x Ω-m
Otherwise Unclassified Properties
Density
1.3 g/cm3 78 lb/ft3
Water Absorption After 24 Hours
0.75 %
Common Calculations
Stiffness to Weight: Axial
0.58 points
Stiffness to Weight: Bending
29 points
Strength to Weight: Axial
6.7 points
Strength to Weight: Bending
17 points
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