PBS vs PBT
Polymer · grade comparison
PBS and PBT are both polymer grades. PBT is the stronger of the two: yield strength 55 MPa (7.98 ksi) against 32 MPa (4.64 ksi) for PBS, about 72% more; tensile strength follows at 55 MPa (7.98 ksi) vs 34 MPa (4.93 ksi). In exchange, PBS is the more ductile: elongation 300% versus 100% for PBT, and PBT is harder (82 Shore D vs 60 Shore D). PBS is lighter (1.26 g/cm³ vs 1.31 g/cm³ for PBT) and PBT is stiffer (2.6 GPa vs 0.6 GPa). On the shop floor, PBT machines more easily (good vs fair) and PBS welds better (excellent vs very good).
PBSChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
PBTChoose it when strength drives the design, or when the part sees heat.
PBS vs PBT: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all polymer grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all polymer grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Flexural Strength
Flexural Modulus
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell R
Shear Modulus
Bulk Modulus
Compressive Strength
Compressive Modulus
Shear Strength
Fracture Toughness (K_IC)
Hardness, Rockwell M
Same in both: Poisson's Ratio 0.4
Physical
Density and transition temperatures.
Density
Melting Temperature (Tm)
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Vicat Softening Point (B50)
Max Service Temperature (short-term)
Same in both: Limiting Oxygen Index 21%
Electrical
Conductivity and insulation.
Volume Resistivity
Electrical Resistivity
Dielectric Strength
Dissipation Factor (1 MHz)
Surface Resistivity
Comparative Tracking Index (CTI)
Same in both: Dielectric Constant (1 MHz) 3.1
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
UV / Weathering Resistance
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Polishability
Mold Shrinkage
Melt Flow Rate
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Typical Recycled Content
Embodied Water
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Same in both: Thermal Diffusivity 0.1 mm²/s · Thermal Shock Resistance Index 0
Strength versus weight
Yield strength against density for every polymer grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | PBS | PBT |
|---|---|---|
| Injection molding | — | Yes |
| Default condition | — | Unfilled |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
| Chrome Plating (Plastic) | — | Yes |
| EMI Shielding Coating | — | Yes |
| Soft Touch Coating | — | Yes |
| Spray Painting | — | Yes |
| UV Coating | — | Yes |
PBS vs PBT — frequently asked
Is PBT stronger than PBS?
Yes. PBT has a typical yield strength of 55 MPa (7.98 ksi) against 32 MPa (4.64 ksi) for PBS — about 72% more. Tensile strength is 55 MPa (7.98 ksi) vs 34 MPa (4.93 ksi).
Which is cheaper, PBS or PBT?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, PBS or PBT?
PBT. Its machinability rates good (68/100) against fair (50/100) for PBS; for welding the order is PBS first (excellent, 85/100) then PBT (very good, 70/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in PBS and PBT side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.