LDPE vs PEX
Polymer · grade comparison
LDPE and PEX are both polymer grades. PEX is the stronger of the two: yield strength 17 MPa (2.47 ksi) against 10 MPa (1.45 ksi) for LDPE, about 70% more; tensile strength follows at 22 MPa (3.19 ksi) vs 11 MPa (1.6 ksi). PEX is the more ductile: elongation 500% versus 450% for LDPE, and PEX is harder (60 Shore D vs 47 Shore D). PEX is stiffer (0.68 GPa vs 0.22 GPa) and PEX runs hotter in service (95°C vs 70°C continuous). On the shop floor, LDPE welds better (excellent vs not recommended) and LDPE sits in a lower cost tier (budget, $) than PEX (standard, $$).
LDPEChoose it when it will be welded, or when cost is the deciding factor.
PEXChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
LDPE 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
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 A
Hardness, Shore D
Tear Strength
Hardness, Rockwell R
Same in both: Poisson's Ratio 0.45
Physical
Density and transition temperatures.
Density
Melting Temperature (Tm)
Glass Transition (Tg)
Water Absorption (Saturation)
Refractive Index
Light Transmission
Same in both: Water Absorption (24 h) 0.01%
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 18%
Electrical
Conductivity and insulation.
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Dielectric Strength 25 kV/mm635 V/mil · 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
UV / Weathering Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Polishability
Melt Flow Rate
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Same in both: Formability (cold) 90 / 100 · Mold Shrinkage 2.5%
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Typical Recycled Content
Same in both: Embodied Water 120 L/kg14.4 gal/lb
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 | LDPE | PEX |
|---|---|---|
| Sheet metal | Yes | — |
| Injection molding | Yes | — |
| Default condition | Unfilled | — |
| Relative cost | $ Budget | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
| Chrome Plating (Plastic) | Yes | — |
| EMI Shielding Coating | Yes | — |
| Painting | Yes | — |
| Soft Touch Coating | Yes | — |
| Spray Painting | Yes | — |
| UV Coating | Yes | — |
LDPE vs PEX — frequently asked
Is PEX stronger than LDPE?
Yes. PEX has a typical yield strength of 17 MPa (2.47 ksi) against 10 MPa (1.45 ksi) for LDPE — about 70% more. Tensile strength is 22 MPa (3.19 ksi) vs 11 MPa (1.6 ksi).
Which is cheaper, LDPE or PEX?
LDPE 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 welds better, LDPE or PEX?
LDPE. Its weldability rates excellent (95/100) against not recommended (10/100) for PEX.
Ready to make it?
Upload a CAD file and FabDigit prices the part in LDPE 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.