MDPE vs PEX
Polymer · grade comparison
MDPE and PEX are both polymer grades. MDPE is the stronger of the two: yield strength 19 MPa (2.76 ksi) against 17 MPa (2.47 ksi) for PEX, about 12% more; tensile strength follows at 24 MPa (3.48 ksi) vs 22 MPa (3.19 ksi). MDPE is the more ductile: elongation 700% versus 500% for PEX. MDPE is stiffer (0.75 GPa vs 0.68 GPa) and PEX runs hotter in service (95°C vs 65°C continuous). On the shop floor, MDPE machines more easily (good vs fair), MDPE welds better (excellent vs not recommended), and MDPE sits in a lower cost tier (budget, $) than PEX (standard, $$).
MDPEChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
PEXChoose it when the part sees heat.
MDPE vs PEX: 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
Shear Modulus
Bulk Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Fracture Toughness (K_IC)
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell R
Hardness, Shore A
Tear Strength
Physical
Density and transition temperatures.
Density
Melting Temperature (Tm)
Glass Transition (Tg)
Refractive Index
Light Transmission
Same in both: Water Absorption (24 h) 0.01% · Water Absorption (Saturation) 0.03%
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
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: Thermal Expansion (CTE, 20–100 °C) 170 µm/m·K94.4 µin/in·°F · Limiting Oxygen Index 18%
Electrical
Conductivity and insulation.
Dielectric Strength
Dissipation Factor (1 MHz)
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Dielectric Constant (1 MHz) 2.3 · Volume Resistivity 1×10¹⁶ Ω·cm · Surface Resistivity 1×10¹⁵ Ω · Comparative Tracking Index (CTI) 600 V
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: UV / Weathering Resistance 25 / 100
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)
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 0.2 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 | MDPE | PEX |
|---|---|---|
| Default condition | — | — |
| Relative cost | $ Budget | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
MDPE vs PEX — frequently asked
Is MDPE stronger than PEX?
Yes. MDPE has a typical yield strength of 19 MPa (2.76 ksi) against 17 MPa (2.47 ksi) for PEX — about 12% more. Tensile strength is 24 MPa (3.48 ksi) vs 22 MPa (3.19 ksi).
Which is cheaper, MDPE or PEX?
MDPE is the lower-cost material: it sits in the budget tier ($) while PEX 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, MDPE or PEX?
MDPE. Its machinability rates good (55/100) against fair (42/100) for PEX; for welding the order is MDPE first (excellent, 95/100) then PEX (not recommended, 10/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in MDPE and PEX 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.