EPP FR (Flame-retardant EPP)
Flame-retardant grade
Specify where transport, rail-interior or appliance fire requirements demand better than plain HB behaviour.
Values for the FR condition
Other EPP grades and fills
EPP is listed in 8 conditions; see the grade overview at EPP.
Compare all 8 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
EPP 20 g/L | Lightest standard grade for low-mass void fill and light protective packaging where loads are small. | 0.18 | 0.25 | 15 | 15 Shore A |
FRThis page Flame-retardant EPP | Specify where transport, rail-interior or appliance fire requirements demand better than plain HB behaviour. | 0.26 | 0.35 | 14 | 18 Shore A |
Cold drawn | Use for ESD-protective trays and shielding-class dunnage needing permanent, humidity-independent conductivity. | — | 0.36 | 15 | — |
EPP30Default EPP 30 g/L | The general-purpose density for reusable packaging, dunnage and automotive trim energy absorbers. | — | 0.4 | 18 | — |
EPP 45 g/L | Choose when heavier parts or higher crush loads must be carried with still-good multi-impact recovery. | 0.45 | 0.6 | 20 | 25 Shore A |
EPP 60 g/L | Used for bumper cores, knee bolsters and heavy-duty returnable containers needing higher plateau stress. | 0.65 | 0.85 | 22 | 30 Shore A |
EPP 90 g/L | For load-bearing cores, tool trays and crash structures where stiffness matters more than mass saving. | 1 | 1 | 24 | 40 Shore A |
EPP 120 g/L | Highest standard density, for severe repeated impact and semi-structural inserts where crush stress must be maximised. | 1 | 2 | 25 | 46 Shore A |
What is EPP FR?
EPP FR is EPP in the FR grade — specify where transport, rail-interior or appliance fire requirements demand better than plain HB behaviour. EPP FR has a tensile strength of 0.35 MPa (0.0508 ksi), weaker than 92% of polymer grades. Elongation at break is 14% and the elastic modulus is 0 GPa (5.08×10⁻⁴ Msi). EPP FR has a density of 0.03 g/cm³ (0.0011 lb/in³), lighter than 94% of polymer grades. Its glass-transition temperature is -12°C (10 °F). EPP30 is the default condition FabDigit quotes; FR is available on request or by drawing note.
Advantages
- Lightweight — 0.03 g/cm³ (0.0011 lb/in³), better than 94% of polymer grades
Limitations
- High mold shrinkage — 2.6%, worse than 96% of polymer grades
- Poor heat conductor — 0.04 W/m·K (0.0202 BTU/hr·ft·°F), worse than 93% of polymer grades
- Low stiffness — 0 GPa (5.08×10⁻⁴ Msi), worse than 92% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
- Absorbs moisture — dry before molding — 0.6%, worse than 75% of polymer grades
EPP FR properties
Typical room-temperature values for EPP FR; 22 are specific to this condition. Other listed values are EPP reference data and may not represent this condition. Bars are the position among polymer grades.
Physical5
EPP FR has a density of 0.03 g/cm³ (0.0011 lb/in³), lighter than 94% of polymer grades. Its glass-transition temperature is -12°C (10 °F).
Mechanical10
EPP FR has a tensile strength of 0.35 MPa (0.0508 ksi), weaker than 92% of polymer grades. Elongation at break is 14% and the elastic modulus is 0 GPa (5.08×10⁻⁴ Msi).
Thermal8
EPP FR is rated for continuous service to 95°C (203 °F). It conducts heat at 0.04 W/m·K (0.0202 BTU/hr·ft·°F), worse than 93% of polymer grades. Thermal expansion is 90 µm/m·K (50 µin/in·°F).
Electrical5
EPP FR has an electrical resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of EPP FR takes about 100 MJ of energy and emits 3.8 kg of CO₂ — less than 61% of polymer grades. Typical recycled content is 10%.
Manufacturability4
EPP FR's machinability is good (58/100, worse than 55% of polymer grades); weldability fair (50/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with EPP FR
Is EPP easy to machine?
Blocks cut cleanly with hot wire, band knife or CNC router at high feed; avoid slow, high-friction tooling that melts and smears the skin.
Can EPP be welded?
Beads fuse to each other by saturated steam in the mould; parts can be joined by hot-air/hot-plate welding, ultrasonic staking or PP-compatible hot-melt and double-sided tape—solvent glues do not bond PP.
Can EPP be formed, bent or molded?
Made by steam-chest bead moulding (typ. 0.20–0.40 MPa steam, ~130–145 °C) after bead pre-expansion; allow 1.5–3.5% shrink plus post-mould stabilization/drying, and design generous draft and steam-hole layout.
What surface finishes work on EPP?
Surfaces accept flame or corona pre-treatment then PP-compatible primer/water-based paint, in-mould films and skins; no plating or anodizing, and printing needs low-tack, low-solvent inks.
EPP chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| ethylene comonomerin random-copolymer EPP beads, lowers fusion temperature | 0 – 8 | 4 |
| blowing agent residue (CO2 / pentane / acell gas largely replaced by air after ageing | 0 – 1 | 0.3 |
| stabilizers / nucleants / pigmentsantioxidant, talc nucleant, colour; carbon black in conductive grades | 0.1 – 3 | 1 |
| propylene (PP repeat unit)high-melt-strength homopolymer or random copolymer base resin | ≥ 92 (balance) | — |
EPP FR — frequently asked
What is EPP FR used for?
EPP FR is typically used for automotive bumper energy absorbers, reusable protective packaging, sound/vibration insulation, sports protective gear and returnable dunnage trays. In short: lightest structural PP form; multi-impact energy absorber; reusable packaging foam.
What is the tensile strength of EPP FR?
EPP FR has a typical tensile strength of 0.35 MPa (0.0508 ksi) — weaker than 92% of polymer grades. Strength varies by condition: see the 8 listed tempers.
Is EPP FR easy to machine?
Reasonably — machinability is rated good (58/100, worse than 55% of polymer grades). Blocks cut cleanly with hot wire, band knife or CNC router at high feed; avoid slow, high-friction tooling that melts and smears the skin.
Can EPP FR be welded?
With care — weldability is rated fair (50/100). Beads fuse to each other by saturated steam in the mould; parts can be joined by hot-air/hot-plate welding, ultrasonic staking or PP-compatible hot-melt and double-sided tape—solvent glues do not bond PP.
What surface finishes work on EPP FR?
Surfaces accept flame or corona pre-treatment then PP-compatible primer/water-based paint, in-mould films and skins; no plating or anodizing, and printing needs low-tack, low-solvent inks.
Can EPP FR be formed, bent or molded?
Made by steam-chest bead moulding (typ. 0.20–0.40 MPa steam, ~130–145 °C) after bead pre-expansion; allow 1.5–3.5% shrink plus post-mould stabilization/drying, and design generous draft and steam-hole layout.
What is the maximum service temperature of EPP FR?
EPP FR is rated for continuous use to about 95°C (203 °F), and briefly to 130°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between EPP30 and EPP120?
EPP30 is the default condition — the general-purpose density for reusable packaging, dunnage and automotive trim energy absorbers. EPP120: highest standard density, for severe repeated impact and semi-structural inserts where crush stress must be maximised.
Sources
- ARPRO Expanded Polypropylene technical data (density range 20–120 g/L) — JSP (2023)
- Neopolen P particle foam product information — BASF (2022)
- Eperan-PP expanded polypropylene data sheets — Kaneka (2022)
- Engineered Materials Handbook Vol. 2: Engineering Plastics (polypropylene) — ASM International (1988)
- Cellular Solids: Structure and Properties — Cambridge University Press (Gibson & Ashby) (1997)
- Polypropylene foam property records — CAMPUS / UL Prospector (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.