PBT vs RPET
Polymer · grade comparison
PBT and RPET are both polymer grades. PBT is the stronger of the two: yield strength 55 MPa (7.98 ksi) against 52 MPa (7.54 ksi) for RPET, about 6% more. PBT is the more ductile: elongation 100% versus 60% for RPET. PBT is lighter (1.31 g/cm³ vs 1.37 g/cm³ for RPET) and PBT runs hotter in service (110°C vs 65°C continuous). On the shop floor, RPET sits in a lower cost tier (budget, $) than PBT (standard, $$).
PBTChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
RPETChoose it when cost is the deciding factor.
PBT vs RPET: 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.
Shear Modulus
Bulk Modulus
Yield Strength (0.2% offset)
Elongation at Break
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Fracture Toughness (K_IC)
Izod Impact, Notched
Hardness, Rockwell M
Same in both: Elastic (Young's) Modulus 2.6 GPa0.38 Msi · Poisson's Ratio 0.4 · Tensile Strength (Ultimate) 55 MPa8 ksi · Compressive Strength 85 MPa12.3 ksi · Hardness, Shore D 82 Shore D · Hardness, Rockwell R 118 HRR
Physical
Density and transition temperatures.
Density
Melting Temperature (Tm)
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
Refractive Index
Light Transmission
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)
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Vicat Softening Point (B50)
Max Service Temperature (short-term)
Same in both: Min Service Temperature -40°C-40 °F · Limiting Oxygen Index 21%
Electrical
Conductivity and insulation.
Dielectric Strength
Dielectric Constant (1 MHz)
Comparative Tracking Index (CTI)
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Dissipation Factor (1 MHz) 0.02 · Volume Resistivity 1×10¹⁶ Ω·cm · Surface Resistivity 1×10¹⁵ Ω
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: UV / Weathering Resistance 35 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Formability (cold)
Polishability
Mold Shrinkage
Melt Flow Rate
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Same in both: Weldability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
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 | PBT | RPET |
|---|---|---|
| Injection molding | Yes | — |
| Default condition | Unfilled | — |
| Relative cost | $$ Standard | $ Budget |
| Min. machined wall | — | — |
| Best machined surface | — | — |
| Chrome Plating (Plastic) | Yes | — |
| EMI Shielding Coating | Yes | — |
| Soft Touch Coating | Yes | — |
| Spray Painting | Yes | — |
| UV Coating | Yes | — |
PBT vs RPET — frequently asked
Is PBT stronger than RPET?
Yes. PBT has a typical yield strength of 55 MPa (7.98 ksi) against 52 MPa (7.54 ksi) for RPET — about 6% more. Tensile strength is 55 MPa (7.98 ksi) vs 55 MPa (7.98 ksi).
Which is cheaper, PBT or RPET?
RPET is the lower-cost material: it sits in the budget tier ($) while PBT is standard ($$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, PBT or RPET?
PBT, by a small margin. Both rate good for machinability — 68/100 against 60/100 for RPET.
Ready to make it?
Upload a CAD file and FabDigit prices the part in PBT and RPET 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.