The material. PHAs are linear polyesters produced in nature by bacterial fermentation of sugar or lipids derived from soybean oil, corn oil, or palm oil. They are fully biodegradable. More than 100 different monomers can be combined within this family to give materials with a wide range of properties, from stiff and brittle thermoplastics to flexible elastomers. The most common type of PHA is PHB (poly-3-hydroxybutyrate), with properties similar to those of PP though it is stiffer and more brittle. The following data is for PHB.
Composition
(CH(CHs)—CH2—CO—O)n General properties
|
Density |
1230 |
– 1250 |
kg/m3 |
|
Price |
3.2 |
– 4 |
USD/kg |
|
Mechanical properties |
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|
Young’s modulus |
0.8 |
– 4 |
GPa |
|
Yield strength (elastic limit) |
35 |
– 40 |
MPa |
|
Tensile strength |
35 |
– 40 |
MPa |
|
Compressive strength |
*40 |
– 45 |
MPa |
|
Elongation |
6 |
– 25 |
% |
|
Hardness—Vickers |
*11 |
– 13 |
HV |
|
Fatigue strength at 107 cycles |
*12 |
– 17 |
MPa |
|
Fracture toughness |
*0.7 |
– 1.2 |
MPa. m1/2 |
|
Thermal properties |
|||
|
Melting point |
115 |
– 175 |
°C |
|
Glass temperature |
4 |
– 15 |
°C |
|
Maximum service temperature |
*60 |
– 80 |
°C |
|
Thermal conductor or insulator? |
Good insulator |
||
|
Thermal conductivity |
*0.13 |
– 0.23 |
W/m. K |
|
Specific heat capacity |
*1400 |
– 1600 |
J/kg. K |
|
Thermal expansion coefficient |
*180 |
– 240 |
p, strain/°C |
|
Electrical properties |
|||
|
Electrical conductor or insulator? |
Good insulator |
||
|
Electrical resistivity |
*1 X 1016 |
– 1X 1018 |
pnhm. cm |
|
Dielectric constant |
*3 |
– 5 |
|
|
Dissipation factor |
*0.05 |
– 0.15 |
|
|
Dielectric strength |
12 |
– 16 106 |
V/m |
PHB containers. (Kumar and Minocha, Trangenic Plant Research, Harwood Publishers.)
Ecoproperties: material
|
Embodied energy, primary production |
50 |
– 59 |
MJ/kg |
|
CO2 footprint, primary production |
*2.25 |
– 2.66 |
kg/kg |
|
Water usage |
*100 |
– 300 |
l/kg |
|
Ecoproperties: processing |
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|
Polymer molding energy |
*8.24 |
– 9.09 |
MJ/kg |
|
Polymer molding CO2 |
*0.65 |
– 0.72 |
kg/kg |
|
Polymer extrusion energy |
*3.21 |
– 3.54 |
MJ/kg |
|
Polymer extrusion CO2 |
*0.25 |
– 0.28 |
kg/kg |
|
Recycling |
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|
Embodied energy, recycling |
21 |
– 24.8 |
MJ/kg |
|
CO2 footprint, recycling |
*0.94 |
– 1.12 |
kg/kg |
|
Recycle fraction in current supply |
0.5 |
– 1 |
% |
|
Recycle mark |
|
Other |
Typical uses. Packaging, containers, bottles.
