XPP FR (Flame-retardant grade)
Flame-retardant grade
GB GB/T 25325
Pick for rail-vehicle and appliance liners required to meet UL 94 HF-1 or GB 8624 B1, usually via a halogen-free phosphorus system; service temperature is capped at 95 °C.
Values for the FR condition
Other XPP grades and fills
XPP is listed in 7 conditions; see the grade overview at XPP.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
XPP-30 | Choose for light cushioning and insulation where minimum weight is the priority and loads are small; the 0.006 GPa modulus limits any load-bearing use. | — | 0.3 | 30 | — |
FRThis page Flame-retardant grade | Pick for rail-vehicle and appliance liners required to meet UL 94 HF-1 or GB 8624 B1, usually via a halogen-free phosphorus system; service temperature is capped at 95 °C. | — | 0.55 | 18 | — |
Carbon-black conductive grade | Choose the carbon-black grade when genuinely conductive shielding packaging at 10⁴–10⁶ Ω is needed to ship sensitive devices; colour is fixed black and tensile strength falls to 0.55 MPa. | — | 0.55 | 15 | — |
Antistatic / dissipative grade | Use for electronic-component cushions and returnable-box liners that must dissipate static charge, holding 0.06 g/cm³ density and 0.6 MPa tensile strength. | — | 0.6 | 22 | — |
D60Default XPP-60 | Use as the default density for general cushioning, thermoformed liners and light sandwich cores, balancing 0.65 MPa tensile strength against a 0.015 GPa modulus. | — | 0.65 | 25 | — |
XPP-90 | Pick for heavy-duty packaging and tooling trays that need higher bearing load and dent resistance; the 0.09 g/cm³ density adds weight and cost over the standard board. | — | 1 | 22 | — |
XPP-130 | Choose as a composite sandwich core co-pressed with GF/PP skins, where the 0.038 GPa modulus and shear strength are highest; 130 kg/m³ is the heaviest and least compliant option. | — | 2 | 18 | — |
What is XPP FR?
XPP FR is XPP in the FR grade — pick for rail-vehicle and appliance liners required to meet UL 94 HF-1 or GB 8624 B1, usually via a halogen-free phosphorus system; service temperature is capped at 95 °C. XPP FR has a tensile strength of 0.55 MPa (0.0798 ksi), weaker than 88% of polymer grades. Elongation at break is 18% and the elastic modulus is 0.01 GPa (0.002 Msi). XPP FR has a density of 0.07 g/cm³ (0.0023 lb/in³), lighter than 87% of polymer grades. Its glass-transition temperature is -10°C (14 °F). D60 is the default condition FabDigit quotes; FR is available on request or by drawing note.
Advantages
- Lightweight — 0.07 g/cm³ (0.0023 lb/in³), better than 87% of polymer grades
- Low embodied carbon — 2.8 kg CO₂/kg, better than 86% of polymer grades
Limitations
- Poor heat conductor — 0.04 W/m·K (0.0225 BTU/hr·ft·°F), worse than 88% of polymer grades
- Low stiffness — 0.01 GPa (0.002 Msi), worse than 77% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
XPP FR properties
Typical room-temperature values for XPP FR; 19 are specific to this condition. Other listed values are XPP reference data and may not represent this condition. Bars are the position among polymer grades.
Physical5
XPP FR has a density of 0.07 g/cm³ (0.0023 lb/in³), lighter than 87% of polymer grades. Its glass-transition temperature is -10°C (14 °F).
Mechanical12
XPP FR has a tensile strength of 0.55 MPa (0.0798 ksi), weaker than 88% of polymer grades. Elongation at break is 18% and the elastic modulus is 0.01 GPa (0.002 Msi).
Thermal8
XPP FR is rated for continuous service to 95°C (203 °F). It conducts heat at 0.04 W/m·K (0.0225 BTU/hr·ft·°F), worse than 88% of polymer grades. Thermal expansion is 90 µm/m·K (50 µin/in·°F).
Electrical5
XPP FR has an electrical resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 74% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of XPP FR takes about 85 MJ of energy and emits 2.8 kg of CO₂ — less than 79% of polymer grades. Typical recycled content is 10%.
Manufacturability6
XPP FR's machinability is good (58/100, worse than 55% of polymer grades); weldability good (65/100); formability very good (78/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with XPP FR
Is XPP easy to machine?
Hot knife or hot wire, die cutting, waterjet and high-speed CNC milling all work. For milling use sharp single-flute cutters at high spindle speed and low feed to prevent melting and chip welding.
Can XPP be welded?
PP-to-PP joints can be made by hot-plate, hot-air or ultrasonic welding. Double-sided tape and hot-melt adhesive are also used; flame or corona treatment first raises surface energy.
Can XPP be formed, bent or molded?
Sheet softens at about 150-165 C for vacuum or pressure thermoforming and can be press-laminated with GF-PP skins into sandwich panels. Unlike EPP beads it cannot be steam-molded into complex three-dimensional parts.
What surface finishes work on XPP?
Surface energy is low, so corona or plasma treatment plus a PP-specific primer is required before painting or printing. Co-extruded PP film or laminated nonwoven facings give a finished surface directly.
XPP 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 |
|---|---|---|
| talc / nucleating agent | 0.3 – 3 | 1 |
| physical blowing agent residue (CO2 / n- | 0.1 – 2 | 0.5 |
| cell-size regulator, antioxidant, proces | 0.2 – 1.5 | 0.5 |
| optional flame retardant (halogen-free PFR variant only | 0 – 12 | 0 |
| optional carbon black / antistatCN / ESD variants only | 0 – 8 | 0 |
| polypropylene (high melt strength homopo | ≥ 90 (balance) | — |
XPP FR — frequently asked
What is XPP FR used for?
XPP FR is typically used for lightweight structural core panels, thermoformed packaging trays, automotive underbody shields, construction insulation boards and reusable container panels. In short: stiffest extruded polyolefin foam; 100 C service temperature; thermoformable board stock.
What is the tensile strength of XPP FR?
XPP FR has a typical tensile strength of 0.55 MPa (0.0798 ksi) — weaker than 88% of polymer grades. Strength varies by condition: see the 7 listed tempers.
Is XPP FR easy to machine?
Reasonably — machinability is rated good (58/100, worse than 55% of polymer grades). Hot knife or hot wire, die cutting, waterjet and high-speed CNC milling all work. For milling use sharp single-flute cutters at high spindle speed and low feed to prevent melting and chip welding.
Can XPP FR be welded?
Yes — weldability is rated good (65/100). PP-to-PP joints can be made by hot-plate, hot-air or ultrasonic welding. Double-sided tape and hot-melt adhesive are also used; flame or corona treatment first raises surface energy.
What surface finishes work on XPP FR?
Surface energy is low, so corona or plasma treatment plus a PP-specific primer is required before painting or printing. Co-extruded PP film or laminated nonwoven facings give a finished surface directly.
Can XPP FR be formed, bent or molded?
Sheet softens at about 150-165 C for vacuum or pressure thermoforming and can be press-laminated with GF-PP skins into sandwich panels. Unlike EPP beads it cannot be steam-molded into complex three-dimensional parts.
What is the maximum service temperature of XPP FR?
XPP 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.
Sources
- ASTM D3575 Standard Test Methods for Flexible Cellular Materials Made from Olefin Polymers — ASTM International (2020)
- UL 94 Tests for Flammability of Plastic Materials (HBF/HF-1 foam classes) — UL (2023)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
- High melt strength PP foam sheet technical data (extruded PP foam producers) — various (Borealis/JSP/Sekisui-type suppliers) (2023)
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.