EPP vs PP-R
Polymer · grade comparison
EPP and PP-R are both polymer grades. PP-R is the stronger of the two: tensile strength 26 MPa (3.77 ksi) against 0.4 MPa (0.058 ksi) for EPP, about 65 times as much. PP-R is the more ductile: elongation 600% versus 18% for EPP. EPP is lighter (0.03 g/cm³ vs 0.91 g/cm³ for PP-R) and PP-R is stiffer (0.85 GPa vs 0 GPa). On the shop floor, PP-R welds better (excellent vs good) and PP-R sits in a lower cost tier (budget, $) than EPP (premium, $$$).
EPPChoose it when weight is the constraint, or when the part sees heat.
PP-RChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
EPP vs PP-R: 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
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Compressive Strength
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Compression Set (22 h, 70 °C)
Shear Modulus
Bulk Modulus
Yield Strength (0.2% offset)
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell R
Physical
Density and transition temperatures.
Density
Melting Temperature (Tm)
Water Absorption (24 h)
Water Absorption (Saturation)
Refractive Index
Same in both: Glass Transition (Tg) -12°C10 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Max Service Temperature (short-term)
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Vicat Softening Point (B50)
Same in both: Specific Heat Capacity 1,900 J/kg·K0.45 BTU/lb·°F · Limiting Oxygen Index 18%
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Constant (1 MHz)
Volume Resistivity
Surface Resistivity
Dielectric Strength
Comparative Tracking Index (CTI)
Same in both: Dissipation Factor (1 MHz) 4×10⁻⁴
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
UV / Weathering Resistance
Same in both: Corrosion Resistance 90 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Mold Shrinkage
Polishability
Melt Flow Rate
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
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)
Thermal Diffusivity
Same in both: 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 | EPP | PP-R |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$ Premium | $ Budget |
| Min. machined wall | — | — |
| Best machined surface | — | — |
EPP vs PP-R — frequently asked
Is PP-R stronger than EPP?
Yes. PP-R has a typical tensile strength of 26 MPa (3.77 ksi) against 0.4 MPa (0.058 ksi) for EPP — about 65 times as much.
Which is cheaper, EPP or PP-R?
PP-R is the lower-cost material: it sits in the budget tier ($) while EPP is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which welds better, EPP or PP-R?
PP-R. Its weldability rates excellent (95/100) against good (55/100) for EPP.
Ready to make it?
Upload a CAD file and FabDigit prices the part in EPP and PP-R 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.