C578 Type IV FR-POLY
Flame-retardant grade
FR-POLY = hBCD-free polymeric brominated flame-retardant formulation
Current standard chemistry for markets restricting HBCD (EU POP, GB 8624 B1 class); same thermal and mechanical performance.
Values for the FR-POLY condition
Other C578 Type IV grades and fills
C578 Type IV is listed in 3 conditions; see the grade overview at C578 Type IV.
Compare all 3 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Thin (6–13 mm) scored fanfold underlayment bundles | Thin Type IV-class sheet used as siding underlayment / re-side board where only a small added R-value and a flat plane are needed. | 0.28 | 0.32 | 3 | — |
High recycled-content (post-industrial/post-consumer PS) board | Specified for green-building credits; property spread is slightly wider than virgin-resin board. | 0.3 | 0.35 | 2.5 | — |
FR-POLYThis page HBCD-free polymeric brominated flame-retardant formulation | Current standard chemistry for markets restricting HBCD (EU POP, GB 8624 B1 class); same thermal and mechanical performance. | 0.35 | 0.4 | 3 | — |
What is C578 Type IV FR-POLY?
C578 Type IV FR-POLY is C578 Type IV in the FR-POLY grade — current standard chemistry for markets restricting HBCD (EU POP, GB 8624 B1 class); same thermal and mechanical performance. C578 Type IV FR-POLY has a tensile strength of 0.4 MPa (0.058 ksi), weaker than 91% of polymer grades. The elastic modulus is 0.01 GPa (0.0019 Msi). C578 Type IV FR-POLY has a density of 0.03 g/cm³ (0.001 lb/in³), lighter than 95% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Advantages
- Lightweight — 0.03 g/cm³ (0.001 lb/in³), better than 95% of polymer grades
- Easy to machine — 90/100, better than 95% of polymer grades
- Low moisture uptake — 0.1%, better than 77% of polymer grades
Limitations
- Hard to polish — 5/100, worse than 99% of polymer grades
- Poor heat conductor — 0.03 W/m·K (0.0168 BTU/hr·ft·°F), worse than 98% of polymer grades
- Degrades in UV without stabilisers — 15/100, worse than 95% of polymer grades
- Low stiffness — 0.01 GPa (0.0019 Msi), worse than 78% of polymer grades
C578 Type IV FR-POLY properties
Typical room-temperature values for C578 Type IV FR-POLY; 17 are specific to this condition. Other listed values are C578 Type IV reference data and may not represent this condition. Bars are the position among polymer grades.
Physical4
C578 Type IV FR-POLY has a density of 0.03 g/cm³ (0.001 lb/in³), lighter than 95% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Mechanical7
C578 Type IV FR-POLY has a tensile strength of 0.4 MPa (0.058 ksi), weaker than 91% of polymer grades. The elastic modulus is 0.01 GPa (0.0019 Msi).
Thermal7
C578 Type IV FR-POLY is rated for continuous service to 74°C (165 °F). It conducts heat at 0.03 W/m·K (0.0168 BTU/hr·ft·°F), worse than 98% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical4
C578 Type IV FR-POLY has an electrical resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of polymer grades. UV resistance is poor.
Sustainability3
Producing a kilogram of C578 Type IV FR-POLY takes about 105 MJ of energy and emits 5.5 kg of CO₂ — more than 54% of polymer grades. Typical recycled content is 15%.
Manufacturability4
C578 Type IV FR-POLY's machinability is excellent (90/100, better than 95% of polymer grades); weldability poor (20/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C578 Type IV FR-POLY
Is C578 Type IV easy to machine?
Cut with hot wire, serrated knife or a sharp router bit at high rpm/low feed; vacuum chip extraction is essential because dust is static-charged.
Can C578 Type IV be welded?
Not thermally welded in practice — panels are joined with T&G edges, low-VOC foam adhesive or mechanical plate anchors.
Can C578 Type IV be formed, bent or molded?
Produced by continuous extrusion with direct gas injection through a slot die and calibrated by cooling plates; boards can be kerf-bent but not thermoformed.
What surface finishes work on C578 Type IV?
Skin must be planed or roughened before cementitious render; protect from UV and from solvent-based mastics, and always cover with a code-required thermal/fire barrier.
C578 Type IV 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 |
|---|---|---|
| blowing agent (HFO-1234ze / CO2 / isobutlegacy grades used HCFC-142b/HFC-134a | 1 – 5 | 3 |
| brominated flame retardant (polymeric bu | 0.5 – 2 | 1 |
| talc / nucleating agentcell-size control | 0.1 – 1 | 0.4 |
| pigment (blue/pink/green identification) | 0 – 0.5 | 0.2 |
| polystyrene (GPPS resin)virgin + recycled PS matrix | ≥ 92 (balance) | — |
C578 Type IV FR-POLY — frequently asked
What is C578 Type IV FR-POLY used for?
C578 Type IV FR-POLY is typically used for below-grade wall insulation, roof insulation and foundation insulation. In short: baseline below-grade XPS; low moisture absorption; widest stock form range.
What is the tensile strength of C578 Type IV FR-POLY?
C578 Type IV FR-POLY has a typical tensile strength of 0.4 MPa (0.058 ksi) — weaker than 91% of polymer grades. Strength varies by condition: see the 3 listed tempers.
Is C578 Type IV FR-POLY easy to machine?
Yes — machinability is rated excellent (90/100, better than 95% of polymer grades). Cut with hot wire, serrated knife or a sharp router bit at high rpm/low feed; vacuum chip extraction is essential because dust is static-charged.
Can C578 Type IV FR-POLY be welded?
Not readily — weldability is rated poor (20/100). Not thermally welded in practice — panels are joined with T&G edges, low-VOC foam adhesive or mechanical plate anchors.
What surface finishes work on C578 Type IV FR-POLY?
Skin must be planed or roughened before cementitious render; protect from UV and from solvent-based mastics, and always cover with a code-required thermal/fire barrier.
Can C578 Type IV FR-POLY be formed, bent or molded?
Produced by continuous extrusion with direct gas injection through a slot die and calibrated by cooling plates; boards can be kerf-bent but not thermoformed.
What is the maximum service temperature of C578 Type IV FR-POLY?
C578 Type IV FR-POLY is rated for continuous use to about 74°C (165 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM C578 — Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation — ASTM International (2022)
- FOAMULAR 250 Extruded Polystyrene Insulation product data — Owens Corning (2023)
- STYROFOAM Brand Extruded Polystyrene Insulation technical data — DuPont Performance Building Solutions (2022)
- ASM Engineered Materials Handbook Vol. 2 — Engineering Plastics (polystyrene foams) — ASM International (1988)
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.