LDPE vs PP
Polymer · grade comparison
LDPE and PP are both polymer grades, both corrosion resistant plastic. PP is the stronger of the two: yield strength 33 MPa (4.79 ksi) against 10 MPa (1.45 ksi) for LDPE, about 3.3 times as much; tensile strength follows at 35 MPa (5.08 ksi) vs 11 MPa (1.6 ksi). In exchange, LDPE is the more ductile: elongation 450% versus 150% for PP, and PP is harder (72 Shore D vs 47 Shore D). PP is stiffer (1.5 GPa vs 0.22 GPa) and PP runs hotter in service (100°C vs 70°C continuous). On the shop floor, PP machines more easily (good vs fair).
LDPEChoose it when the part is bent, formed or impact-loaded.
PPChoose it when strength drives the design, or when the part sees heat.
LDPE vs PP: 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 A
Hardness, Shore D
Tear Strength
Hardness, Rockwell R
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)
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)
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Dielectric Strength 25 kV/mm635 V/mil · Dissipation Factor (1 MHz) 3×10⁻⁴ · 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 20 / 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
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 | LDPE | PP |
|---|---|---|
| CNC machining | — | Yes |
| 3D printing | — | Yes |
| Default condition | Unfilled | Homopolymer |
| Relative cost | $ Budget | $ Budget |
| Min. machined wall | — | 0.5 mm |
| Best machined surface | — | Ra 0.8 µm |
| Conductive Coating | — | Yes |
| Dyeing (Nylon) | — | Yes |
| Primer Coating | — | Yes |
| Tinted Coating | — | Yes |
| Vacuum Metallization | — | Yes |
| Waterproof Coating | — | Yes |
Both are offered for Sheet metal and Injection molding. They share 6 finishes: Chrome Plating (Plastic), EMI Shielding Coating, Painting, Soft Touch Coating, Spray Painting, UV Coating.
LDPE vs PP — frequently asked
Is PP stronger than LDPE?
Yes. PP has a typical yield strength of 33 MPa (4.79 ksi) against 10 MPa (1.45 ksi) for LDPE — about 3.3 times as much. Tensile strength is 35 MPa (5.08 ksi) vs 11 MPa (1.6 ksi).
Which is cheaper, LDPE or PP?
Both sit in the same relative cost tier ($, budget); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, LDPE or PP?
PP. Its machinability rates good (60/100) against fair (45/100) for LDPE.
Ready to make it?
Upload a CAD file and FabDigit prices the part in LDPE and PP 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.