Polyetherketoneketone PEKK
Poly(ether ketone ketone), a semi-crystalline PAEK copolymer of terephthalic and isophthalic moieties
PEKK is a semi-crystalline PAEK thermoplastic with a high ketone content and a terephthalic/isophthalic copolymer structure.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Stiffness
4000 MPa
Heat
162 °C glass transition
Fire
V-0 at 0.8 mm
Printed strength
93.9 MPa
Recipe, share of the weight
- T not statedTerephthalic moiety
- I not statedIsophthalic moiety
- O, CO not statedEther and ketone links
Best for
Stiff, flame-resistant thermoplastic for filament-printed or fibre-reinforced structural parts that must stay rigid at 150 °C and above (LOI 38 %, V-0 at 0.8 mm)
Weakest at
Printed parts, where crystallinity in the printed layers sets strength and ductility (tensile strength fell about 49 % when the top layer crystallized), and where printed stiffness fell far below the datasheet value. No space ageing data.
Risk at a glance
- People None found. Not classified in the sources read
- If it fails High. Strength loss at elevated temperature
- Corrosion Low. PEKK takes up about 0.4 % water at 50 % humidity and 0.7 % in immersion, at equilibrium.
Quick facts: PEKK
| Property | Value | Basis |
|---|---|---|
| Density | 1.29 g/cm³ | 1 sourced value |
| Yield strength | 110 to 120 MPa | 1 sourced value |
| Tensile strength | 93.9 to 116 MPa | 2 sourced values across conditions |
| Young's modulus | 1.06 to 4 GPa | 4 sourced values across conditions |
| Thermal expansion (CTE) | 23 µm/m/K | 1 sourced value |
| Melting point | 325 to 360 °C | 3 sourced values across conditions |
| Specific heat | 1.02 J/g/K | 1 sourced value |
What is the density of Polyetherketoneketone (PEKK)?
Polyetherketoneketone (PEKK) has a density of 1.29 g/cm³. The source and test conditions are listed in the properties table on this page.
What is the coefficient of thermal expansion of Polyetherketoneketone (PEKK)?
Polyetherketoneketone (PEKK) has a coefficient of thermal expansion of 23 µm/m/K. The source and test conditions are listed in the properties table on this page.
What is the melting point of Polyetherketoneketone (PEKK)?
Polyetherketoneketone (PEKK) has a melting point of 325 to 360 °C. The range covers 3 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the yield strength of Polyetherketoneketone (PEKK)?
Polyetherketoneketone (PEKK) has a yield strength of 110 to 120 MPa. The source and test conditions are listed in the properties table on this page.
What is the tensile strength of Polyetherketoneketone (PEKK)?
Polyetherketoneketone (PEKK) has a tensile strength of 93.9 to 116 MPa. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is Polyetherketoneketone (PEKK) used for?
Uses recorded in the sources include Fused-filament-printed PEKK parts from an open-chamber printer (ground tests only); Continuous-fibre composites and filament printing with the 7000 series grades (manufacturer application statement).
Why it exists
PEKK is a semi-crystalline thermoplastic in the PAEK family. Its ketone-rich chain and aromatic rings keep it stiff at high temperature, and the choice of terephthalic and isophthalic units sets how fast it crystallizes. That lets one family cover amorphous grades for low-temperature processing and semi-crystalline grades for stiffness. The Kepstan 7000 series is sold for filament printing, because its slower crystallization eases interlayer adhesion, and the same paper family reports that PEKK keeps no observable difference between filament and printed parts, while PEEK loses some glass transition on printing.
Where it's used
Printed structural parts
Printed PEKK C filament reached a tensile strength of 93.9 MPa in an open-chamber printer, which the authors compare with enclosed systems. These are ground test coupons, not flight parts.
Composite and filament structures
Arkema describes the 7000 series as highly enabling for continuous-fibre composite structures and for filament additive manufacturing. The datasheet does not name a specific part.
Recipe
Poly(ether ketone ketone), a semi-crystalline PAEK copolymer of terephthalic and isophthalic moieties
PEKK is a poly(aryl ether ketone ketone) copolymer. Arkema builds its Kepstan grades on a PEKK backbone with a high ketone content and a copolymer of terephthalic and isophthalic units, with the ratio setting crystallization speed (6000 series amorphous, 7000 and 8000 series semi-crystalline). The chain is stiff because of the aromatic rings and ketone links.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Terephthalic moiety T | not stated | Para-linked aromatic unit in the copolymer. It favours a more regular chain and faster crystallization. |
| Isophthalic moiety I | not stated | Meta-linked aromatic unit. It lowers crystallinity and slows crystallization, which is why the 6000 series is pseudo-amorphous. |
| Ether and ketone links O, CO | not stated | Ether links give flexibility of the chain; ketone links give the high-temperature stiffness. |
Weight shares are as printed in the sources.
What it can do
Stiffness
4000 MPa
The 7003 grade has a tensile modulus of 4000 MPa and a yield stress of 110 to 120 MPa at 23 °C, from injection-moulded specimens. The printed PEKK in the Rodzen paper was far less stiff, at 1060.4 MPa.
Heat
162 °C glass transition
The 7003 grade has a glass transition of 162 °C and a heat deflection temperature of 164 °C at 1.8 MPa. The 8003 grade melts at 360 °C and has a glass transition of 165 °C.
Fire
V-0 at 0.8 mm
The 7003 sheet gives a limiting oxygen index of 38 % and a V-0 rating at a nominal thickness of 0.8 mm (IEC 60695-11-10).
Printed strength
93.9 MPa
Printed PEKK C in the amorphous top-layer condition reached 93.9 ± 5.5 MPa tensile strength, with 12.2 ± 1.5 % strain at break.
How it compares
Against PEI, the Glaskova study found PEKK stiffer and stronger when printed at a 0 degree raster angle (18.2 % and 6.0 % higher in modulus and strength) and much stronger at 45 degrees (41.1 % higher modulus and 104.4 % higher tensile strength), with more uniform behaviour across print directions. Against PEEK, the Garcia 2021 study found that printed PEEK bars had a glass transition of 146.8 °C, about 8 °C below the 154.8 °C of the parent filament, while printed PEKK showed no observable difference from its filament. Arkema's 6000 series also states a high ketone content and a copolymer structure, which is how PEKK differs from PEEK in chemistry, but no PEEK value from the same run is used here.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | PEKK | PAI | PBI | PBO (Zylon) | PEEK | PEI | PEK | PES | PPS | PPSU | PSU |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Thermal behavior and safety | |||||||||||
| Melting temperature, Kepstan 8003 | 360 °C2 | no data | no data | no data | 343 °C | no data | 373 °C | no data | 536 °F | no data | no data |
| Melting temperature, Kepstan 7003 | 336 °C3 | no data | no data | no data | 343 °C | no data | 373 °C | no data | 536 °F | no data | no data |
| Melting temperature, Kepstan 7001 | 325 °C4 | no data | no data | no data | 343 °C | no data | 373 °C | no data | 536 °F | no data | no data |
| Heat deflection temperature at 1.8 MPa, Kepstan 7003 | 164 °C8 | 278 °C | 435 °C | no data | no data | 173 °C | 163 °C | 205 °C | 400 °F | 207 °C | 174 °C |
| Specific heat capacity, Kepstan 7003 | 1.02 J/g/K21 | no data | no data | no data | no data | no data | 2200 J/kg/°C | no data | no data | no data | no data |
| Physical and electrical | |||||||||||
| Density, Kepstan 7003 | 1.29 g/cm³1 | 1.41 g/cc | 1.276 g/cm³ | 1.398 g/cm³ | 1.3 g/cm³ | 1.34 g/cm³ | 1.3 g/cm³ | 1370 kg/m3 | 1.36 g/cm³ | 1.29 g/cm³ | 1.22 g/cm³ |
| Temperature behavior | |||||||||||
| Glass transition temperature, Kepstan 8003 | 165 °C5 | 275 °C | 425 °C | no data | no data | 186 °C | 160 °C | 225 °C | 90 °C | 220 °C | 190 °C |
| Glass transition temperature, Kepstan 7003 | 162 °C6 | 275 °C | 425 °C | no data | no data | 186 °C | 160 °C | 225 °C | 90 °C | 220 °C | 190 °C |
| Glass transition temperature, Kepstan 6002 (amorphous) | 158 °C7 | 275 °C | 425 °C | no data | no data | 186 °C | 160 °C | 225 °C | 90 °C | 220 °C | 190 °C |
| Other measurements | |||||||||||
| Tensile modulus, Kepstan 7003 | 4000 MPa9 | 4136 MPa | 5.9 GPa | 147.1 GPa | no data | 3200 MPa | 4300 MPa | 2640 MPa | 8.37×10^5 psi | 2340 MPa | 2480 MPa |
| Tensile modulus, Kepstan 8002 | 3.8 GPa10 | 4136 MPa | 5.9 GPa | 147.1 GPa | no data | 3200 MPa | 4300 MPa | 2640 MPa | 8.37×10^5 psi | 2340 MPa | 2480 MPa |
| Tensile modulus, Kepstan 6002 (amorphous) | 2.9 GPa11 | 4136 MPa | 5.9 GPa | 147.1 GPa | no data | 3200 MPa | 4300 MPa | 2640 MPa | 8.37×10^5 psi | 2340 MPa | 2480 MPa |
| Tensile modulus of printed PEKK (open-chamber FFF, amorphous top layer) | 1060 MPa12 | 4136 MPa | 5.9 GPa | 147.1 GPa | no data | 3200 MPa | 4300 MPa | 2640 MPa | 8.37×10^5 psi | 2340 MPa | 2480 MPa |
| Tensile yield stress, Kepstan 7003 | 110 to 120 MPa13 | no data | no data | no data | no data | 110 MPa | 115 MPa | 86 MPa | 13700 psi | 74 MPa | no data |
| Tensile strength (maximum strength), Kepstan 8002 | 116 MPa14 | 138 MPa | 160 MPa | 5.34 GPa | no data | no data | no data | no data | 200 MPa | 69.6 MPa | 70.3 MPa |
| Tensile strength of printed PEKK (open-chamber FFF, amorphous top layer) | 93.9 MPa15 | 138 MPa | 160 MPa | 5.34 GPa | no data | no data | no data | no data | 200 MPa | 69.6 MPa | 70.3 MPa |
| Elongation at break, Kepstan 7003 | 3 to 10 %16 | 20 % | 3 % | 3.52 % | no data | 50 % | 15 % | no data | 2.5 % | 60 to 120 % | 50 % |
| Elongation at break, Kepstan 8002 | 20 %17 | 20 % | 3 % | 3.52 % | no data | 50 % | 15 % | no data | 2.5 % | 60 to 120 % | 50 % |
| Flexural modulus, Kepstan 8002 | 3.9 GPa18 | 4136 MPa | no data | no data | no data | 2400 MPa | 4000 MPa | no data | 6.31×10^5 psi | 2410 MPa | 2690 MPa |
| Flexural strength (maximum), Kepstan 8002 | 180 MPa19 | 165 MPa | no data | no data | no data | 100 MPa | 170 MPa | no data | 20400 psi | 91 MPa | 106 MPa |
| Coefficient of thermal expansion, -100 °C to Tg, Kepstan 8002 | 23 µm/m/K20 | 3.1×10^-5 1/°C | 23 10-6 K-1 | no data | no data | 5.2×10^-5 1/°C | 55 ppm/K | 52 E-6/K | 2.6×10^-5 cm/cm/°C | 55 E-6/K | 5.6×10^-5 1/°C |
| Water absorption at equilibrium, 23 °C and 50 % RH, Kepstan 7003 | 0.4 %22 | 0.4 % | 0.4 % | no data | no data | 0.25 % | 0.6 % | 2.2 % | 0.01 % | 1.1 % | 0.3 % |
| Dielectric strength, 100 µm film, Kepstan 7003 | 84 kV/mm23 | 580 V/mil | 21 kV/mm | no data | no data | no data | 23 kV/mm | 37 kV/mm | 450 V/mil | 15 kV/mm | 17 kV/mm |
| Relative permittivity, 23 °C and 1 MHz, Kepstan 7003 | 3 -24 | 4.2 - | 3.2 - | no data | no data | no data | no data | 3.9 - | 3 - | 3.44 - | 3.03 - |
| Loss tangent, 23 °C and 1 kHz, Kepstan 8002 | 0.002 -25 | no data | no data | no data | no data | no data | no data | 17 E-4 | 0.001 - | no data | no data |
| Limiting oxygen index, Kepstan 7003 | 38 % O226 | no data | 58 % | no data | no data | no data | no data | no data | no data | no data | no data |
| Charpy notched impact strength, 23 °C, Kepstan 7003 | 4.5 kJ/m227 | no data | no data | no data | no data | no data | 3.8 kJ/m2 | no data | no data | no data | no data |
Why choose it, and why not
Good for
- Stiffness at temperature. The 7003 grade has a tensile modulus of 4000 MPa and a glass transition of 162 °C.
- Flame resistance. A limiting oxygen index of 38 % and V-0 at 0.8 mm.
- Printed parts with control. Printed PEKK reached 93.9 MPa when the top layer stayed amorphous.
Watch out for
- Printed stiffness. Printed PEKK had a tensile modulus of 1060.4 MPa against 4000 MPa for injection-moulded material.
- Crystallized top layers. Tensile strength fell by about 49 % when the top layer crystallized.
- Heat. Tensile strength at the yield point fell to 24 MPa at 175 °C for the 8002 grade.
- Ageing. No UV or long-term heat-ageing number for PEKK was found, so long service in sunlight or hot environments is untested.
PEKK is a stiff, flame-resistant, heat-tolerant thermoplastic with good datasheet properties, but the printed-part numbers are much lower than the datasheet. Test printed parts directly before using them in a load-bearing design, and treat any space use as untested.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density, Kepstan 7003 | Value in the manufacturer's technical data sheet, Other properties table | grade KEPSTAN 7003 (unfilled, pellet)test standard ISO 1183-1temperature 23 °C | The same density, 1.29 g/cm3, is printed for every 7000 and 8000 series grade, and 1.27 g/cm3 for the 6000 series (amorphous). |
| 2 | Melting temperature, Kepstan 8003 | Value in the manufacturer's technical data sheet, Thermal properties table | grade KEPSTAN 8003 (high flow, 8000 series)test standard DSC, 20 °C/min, 2nd heating | The 8001 grade is 355 °C and the 8002 grade 360 °C in the 8000 series sheet. |
| 3 | Melting temperature, Kepstan 7003 | Value in the manufacturer's technical data sheet, Thermal properties table | grade KEPSTAN 7003 (high flow, 7000 series)test standard DSC, 20 °C/min, 2nd heating | The 7001 grade melts at 325 °C; the 7000 series is chosen where a lower melting point and slower crystallization help printing and thermoforming. |
| 4 | Melting temperature, Kepstan 7001 | Value in the 7000 series technical data sheet, thermal table | grade KEPSTAN 7001 (very low flow, 7000 series)test standard DSC, 20 °C/min, 2nd heating | — |
| 5 | Glass transition temperature, Kepstan 8003 | Value in the manufacturer's technical data sheet, Thermal properties table | grade KEPSTAN 8003test standard DSC, 20 °C/min | The 8000 series sheet gives 165 °C for all three grades (8001, 8002 and 8003). |
| 6 | Glass transition temperature, Kepstan 7003 | Value in the manufacturer's technical data sheet, Thermal properties table | grade KEPSTAN 7003test standard DSC, 20 °C/min | — |
| 7 | Glass transition temperature, Kepstan 6002 (amorphous) | Value in the 6000 series technical data sheet, thermal table; the sheet says the properties correspond to the amorphous state | grade KEPSTAN 6002 (pseudo-amorphous, 6000 series)test standard DSC, 20 °C/minstate amorphous | The 6000 series has no melting point in the sheet (n/a), so it can be processed as low as 320 to 330 °C. |
| 8 | Heat deflection temperature at 1.8 MPa, Kepstan 7003 | Value in the manufacturer's technical data sheet, Mechanical and thermal properties | grade KEPSTAN 7003test standard ISO 75-1/-2 at 1.8 MPa | — |
| 9 | Tensile modulus, Kepstan 7003 | Value in the manufacturer's technical data sheet, Mechanical properties table | grade KEPSTAN 7003 (injection-moulded specimens)test standard ISO 527-1/-2 (1BA), 23 °C | — |
| 10 | Tensile modulus, Kepstan 8002 | Value in the 8000 series technical data sheet, mechanical table | grade KEPSTAN 8002 (medium flow, 8000 series)test standard ISO 527-A12, 1 mm/min, 23 °C | Per the same table, the 8001 grade is 3.6 GPa and the 8003 grade 4.1 GPa. |
| 11 | Tensile modulus, Kepstan 6002 (amorphous) | Value in the 6000 series technical data sheet, mechanical table | grade KEPSTAN 6002 (amorphous)test standard ISO 527-A12, 1 mm/min, 23 °Cstate amorphous injection-moulded | — |
| 12 | Tensile modulus of printed PEKK (open-chamber FFF, amorphous top layer) | Mean of five specimens reported by the paper, Table 2 | specimen FFF-printed PEKK C (ThermaX filament, 3DXTech; the paper says it is believed to be Kepstan 7002), amorphous top-layer specimenstest tensile, N = 5 | Uncertainty: standard deviation 30.6 MPaRoughly a quarter of the 4000 MPa datasheet value for Kepstan 7003, so the printed part is far less stiff than injection-moulded material. |
| 13 | Tensile yield stress, Kepstan 7003 | Range in the manufacturer's technical data sheet, Mechanical properties table | grade KEPSTAN 7003 (injection-moulded specimens)test standard ISO 527-1/-2 (1BA), 23 °C | The 7000 series sheet prints 100 to 120 MPa for 7003 under the same heading, so the two Arkema sheets differ slightly. |
| 14 | Tensile strength (maximum strength), Kepstan 8002 | Value in the 8000 series technical data sheet, mechanical table | grade KEPSTAN 8002 (injection-moulded specimens)test standard ISO 527-A12, 23 °C | Tensile strength of the 8001 grade is 110 MPa and the 8003 range 100 to 120 MPa on the same sheet. |
| 15 | Tensile strength of printed PEKK (open-chamber FFF, amorphous top layer) | Mean of five specimens reported by the paper, Table 2 | specimen FFF-printed PEKK C (ThermaX filament, 3DXTech), amorphous top-layer specimenstest tensile, N = 5 | Uncertainty: standard deviation 5.5 MPaThe paper's abstract gives the same figure. Strain at break was 12.2 ± 1.5 % for these specimens. |
| 16 | Elongation at break, Kepstan 7003 | Range in the manufacturer's technical data sheet, Mechanical properties table | grade KEPSTAN 7003 (injection-moulded specimens)test standard ISO 527-1/-2 (1BA), 23 °C | — |
| 17 | Elongation at break, Kepstan 8002 | Value in the 8000 series technical data sheet, mechanical table | grade KEPSTAN 8002 (injection-moulded specimens)test standard ISO 527-A12, 23 °C | The 8003 grade on the same sheet breaks at 3 to 10 %, so strain at break depends strongly on the flow grade. |
| 18 | Flexural modulus, Kepstan 8002 | Value in the 8000 series technical data sheet, mechanical table | grade KEPSTAN 8002test standard ISO 178, 23 °C | — |
| 19 | Flexural strength (maximum), Kepstan 8002 | Value in the 8000 series technical data sheet, mechanical table | grade KEPSTAN 8002test standard ISO 178, 23 °C | The same sheet gives 25 MPa for the 8002 grade at 175 °C, so the flexural strength drops sharply with heat. |
| 20 | Coefficient of thermal expansion, -100 °C to Tg, Kepstan 8002 | Value in the 8000 series technical data sheet, thermal table | grade KEPSTAN 8002method detail DMA, tension, average from -100 °C to Tg | Above Tg and up to 300 °C the sheet gives 225 µm/m/K. |
| 21 | Specific heat capacity, Kepstan 7003 | Value in the manufacturer's technical data sheet, Thermal properties table | grade KEPSTAN 7003temperature 23 °C | — |
| 22 | Water absorption at equilibrium, 23 °C and 50 % RH, Kepstan 7003 | Value in the manufacturer's technical data sheet, Other properties table | grade KEPSTAN 7003test standard ISO 62, 23 °C, 50 % RH, equilibrium | At equilibrium in immersion the same sheet gives 0.7 %, and after 24 h in 50 % RH 0.05 % for a 2 mm specimen. |
| 23 | Dielectric strength, 100 µm film, Kepstan 7003 | Value in the manufacturer's technical data sheet, Electrical properties table | grade KEPSTAN 7003test standard IEC 60243-1, 100 µm thickness | — |
| 24 | Relative permittivity, 23 °C and 1 MHz, Kepstan 7003 | Value in the manufacturer's technical data sheet, Electrical properties table | grade KEPSTAN 7003test standard IEC 62631-2-1, 23 °C, 1 MHz | — |
| 25 | Loss tangent, 23 °C and 1 kHz, Kepstan 8002 | Value in the 8000 series technical data sheet, electrical table | grade KEPSTAN 8002test standard IEC 60250, 23 °C, 1 kHz | — |
| 26 | Limiting oxygen index, Kepstan 7003 | Value in the manufacturer's technical data sheet, Thermal properties table | grade KEPSTAN 7003test standard ISO 4589-1/-2, nominal thickness 3.2 mm | The same sheet gives burning behaviour of V-0 at a nominal thickness of 0.8 mm (IEC 60695-11-10). |
| 27 | Charpy notched impact strength, 23 °C, Kepstan 7003 | Value in the manufacturer's technical data sheet, Mechanical properties table | grade KEPSTAN 7003test standard ISO 179 1eA, 23 °C | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Water vapour and immersion at 23 °C | low | PEKK takes up about 0.4 % water at 50 % humidity and 0.7 % in immersion, at equilibrium.1 |
| Heat over service life | not rated | No long-term heat-ageing test was found; the datasheets give short-term heat deflection and glass transition only.2 |
| Ultraviolet light | not rated | No UV-ageing number for PEKK was read; the datasheet only asks for UV-protected storage.3 |
| Chemicals and solvents | not rated | Arkema describes chemical resistance in general terms only; no chemical-resistance table was read.4 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Water vapour and immersion at 23 °C | Equilibrium water absorption is 0.4 % at 23 °C and 50 % relative humidity, and 0.7 % in immersion (ISO 62, KEPSTAN 7003). These are uptake figures; no wet-and-dry ageing test was read in this run. | grade KEPSTAN 7003test standard ISO 62 |
| 2 | Heat over service life | KEPSTAN 7003 has a heat deflection temperature of 164 °C at 1.8 MPa and a glass transition of 162 °C. For the 8002 grade the sheet gives a yield stress of 24 MPa at 175 °C in a short tensile test at 25 mm/min, which is not an ageing result. | basis short-term tests on datasheets |
| 3 | Ultraviolet light | KEPSTAN 7003 gives an indefinite shelf life when stored sealed with appropriate UV protection and temperature. The 2016 carbon-fibre PEKK ageing paper (J. Thermoplastic Composite Materials, DOI 10.1177/0892705714564283) could not be opened (HTTP 403), so its UV findings are not used. | basis storage statement only |
| 4 | Chemicals and solvents | The 8000 series product description cites chemical and fire resistance from the semi-crystalline solid state. No acid, base or solvent test was read in this run. | basis product description only |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
No Arkema safety data sheet was read, so there is no hazard classification for the resin, only processing guidance.
- The resin
- The datasheets describe handling and processing only. They give no toxicology or hazard statements, so treat the resin as unknown rather than safe.
- Melt
- The 8000 series is processed at 375 to 385 °C, so hot polymer and fume from melting are a concern. The sources read do not give fume or burn data.
If a part fails
These results come from printed test coupons and datasheet tests, not from failures of finished parts.
- Printed layers
- When the top layer of a printed part crystallized, tensile strength fell by about 49 %, because the layer interface became brittle.
- Printed stiffness
- Printed tensile modulus was 1060.4 MPa, far below the 4000 MPa of injection-moulded Kepstan 7003.
- Heat
- Tensile strength at the yield point fell to 24 MPa at 175 °C for the 8002 grade, against 116 MPa maximum strength at 23 °C.
Handling and storage
- Drying
- Dry the pellets before processing, at 150 °C for 3 to 4 hours or 120 °C for 6 to 8 hours.
- Storage
- Keep the resin sealed and UV-protected; Arkema gives an indefinite shelf life under those conditions.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Brittle interlayer in printed PEKKmoderate severity | Top layer of a printed part allowed to crystallize (open-chamber FFF, no top-layer temperature control)Excess crystallization causes brittleness through poor chain entanglement at the layer interface. The paper reports the tensile strength of the crystallized batch was reduced by about 49 % relative to the amorphous top layer. |
| Low stiffness of printed PEKKmoderate severity | Fused-filament printing of PEKK C filament, amorphous top layer, tensile testPrinted tensile modulus was 1060.4 MPa, against the 4000 MPa datasheet value for injection-moulded Kepstan 7003, so stiffness-critical printed parts need their own test data. |
| Strength loss at elevated temperaturehigh severity | Tensile test at 175 °C (8002 grade, ISO 527-A12, 25 mm/min)Tensile strength at the yield point falls to 24 MPa at 175 °C, against 116 MPa maximum strength at 23 °C, so a loaded part should stay well below this temperature. |
Handling and storage
- Melt-process the 8000 series at 375 to 385 °C (extrusion and injection), and dry the resin first: 150 °C for 3 to 4 hours, or 120 °C for 6 to 8 hours.
- Store sealed, with UV protection and at a controlled temperature; the 7003 sheet gives an indefinite shelf life under those conditions.
Mitigations
- Keep the top layer below its crystallization threshold and control its temperature (halogen heater on an open-chamber printer) to keep ductility.
Supply and geography
How common the raw materials are and where they come from.
PEKK polymer (Kepstan)
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
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spore: profile
id: pekk
spore_version: 0.2
family: high-performance-polymers
name: Polyetherketoneketone
abbreviation: PEKK
role: structural/insulating polymer
category: polymers
type: high-performance
summary: |
PEKK is a semi-crystalline PAEK thermoplastic with a high ketone content and a terephthalic/isophthalic copolymer structure. Arkema's Kepstan 7003 datasheet, a grade sold for filament printing, gives a density of 1.29 g/cm3, a glass transition of 162 °C and a melting point of 336 °C; the 8003 grade melts at 360 °C. Parts printed from ThermaX PEKK C filament in an open-chamber printer reached a tensile strength of 93.9 ± 5.5 MPa, but their tensile modulus was 1060.4 MPa, about a quarter of the 4000 MPa datasheet value, so print conditions matter as much as the grade. No flight, atomic-oxygen or UV-ageing number for PEKK was read in this run.
best_for: Stiff, flame-resistant thermoplastic for filament-printed or fibre-reinforced structural parts that must stay rigid at 150 °C and above (LOI 38 %, V-0 at 0.8 mm)
weakest_at: Printed parts, where crystallinity in the printed layers sets strength and ductility (tensile strength fell about 49 % when the top layer crystallized), and where printed stiffness fell far below the datasheet value. No space ageing data.
identity:
formula: Poly(ether ketone ketone), a semi-crystalline PAEK copolymer of terephthalic and isophthalic moieties
source: arkema-6000
where: 'Product description of the Kepstan 6000 series datasheet (Rev Nov 2024): PEKK backbone with a high ketone content and a copolymer structure incorporating terephthalic and isophthalic moieties. No repeat-unit formula or CAS number for PEKK was confirmed on a fetched page; the Wikipedia infobox gives CAS 29658-26-2 but that number is not confirmed for PEKK, so it is not entered.'
tags:
environments: []
stresses:
- extreme-heat
applications:
- structures
properties:
- benchmark: density
label: Density, Kepstan 7003
value: 1.29
unit: g/cm3
scope: material
conditions:
grade: KEPSTAN 7003 (unfilled, pellet)
test_standard: ISO 1183-1
temperature: 23 degC
method: Value in the manufacturer's technical data sheet, Other properties table
status: ground
note: The same density, 1.29 g/cm3, is printed for every 7000 and 8000 series grade, and 1.27 g/cm3 for the 6000 series (amorphous).
source: arkema-7003
where: Other properties table
- benchmark: melting_point
label: Melting temperature, Kepstan 8003
value: 360
unit: °C
scope: material
conditions:
grade: KEPSTAN 8003 (high flow, 8000 series)
test_standard: DSC, 20 °C/min, 2nd heating
method: Value in the manufacturer's technical data sheet, Thermal properties table
status: ground
note: The 8001 grade is 355 °C and the 8002 grade 360 °C in the 8000 series sheet.
source: arkema-8003
where: Thermal properties table
- benchmark: melting_point
label: Melting temperature, Kepstan 7003
value: 336
unit: °C
scope: material
conditions:
grade: KEPSTAN 7003 (high flow, 7000 series)
test_standard: DSC, 20 °C/min, 2nd heating
method: Value in the manufacturer's technical data sheet, Thermal properties table
status: ground
note: The 7001 grade melts at 325 °C; the 7000 series is chosen where a lower melting point and slower crystallization help printing and thermoforming.
source: arkema-7003
where: Thermal properties table
- benchmark: melting_point
label: Melting temperature, Kepstan 7001
value: 325
unit: °C
scope: material
conditions:
grade: KEPSTAN 7001 (very low flow, 7000 series)
test_standard: DSC, 20 °C/min, 2nd heating
method: Value in the 7000 series technical data sheet, thermal table
status: ground
source: arkema-7000
where: Material properties table, Thermal, Melting point row
- benchmark: glass_transition_temperature
label: Glass transition temperature, Kepstan 8003
value: 165
unit: °C
scope: material
conditions:
grade: KEPSTAN 8003
test_standard: DSC, 20 °C/min
method: Value in the manufacturer's technical data sheet, Thermal properties table
status: ground
note: The 8000 series sheet gives 165 °C for all three grades (8001, 8002 and 8003).
source: arkema-8003
where: Thermal properties table
- benchmark: glass_transition_temperature
label: Glass transition temperature, Kepstan 7003
value: 162
unit: °C
scope: material
conditions:
grade: KEPSTAN 7003
test_standard: DSC, 20 °C/min
method: Value in the manufacturer's technical data sheet, Thermal properties table
status: ground
source: arkema-7003
where: Thermal properties table
- benchmark: glass_transition_temperature
label: Glass transition temperature, Kepstan 6002 (amorphous)
value: 158
unit: °C
scope: material
conditions:
grade: KEPSTAN 6002 (pseudo-amorphous, 6000 series)
test_standard: DSC, 20 °C/min
state: amorphous
method: Value in the 6000 series technical data sheet, thermal table; the sheet says the properties correspond to the amorphous state
status: ground
note: The 6000 series has no melting point in the sheet (n/a), so it can be processed as low as 320 to 330 °C.
source: arkema-6000
where: Material properties table, Thermal; product description
- benchmark: heat_deflection_temperature
label: Heat deflection temperature at 1.8 MPa, Kepstan 7003
value: 164
unit: °C
scope: material
conditions:
grade: KEPSTAN 7003
test_standard: ISO 75-1/-2 at 1.8 MPa
method: Value in the manufacturer's technical data sheet, Mechanical and thermal properties
status: ground
source: arkema-7003
where: Thermal properties table
- benchmark: elastic_modulus
label: Tensile modulus, Kepstan 7003
value: 4000
unit: MPa
scope: material
conditions:
grade: KEPSTAN 7003 (injection-moulded specimens)
test_standard: ISO 527-1/-2 (1BA), 23 °C
method: Value in the manufacturer's technical data sheet, Mechanical properties table
status: ground
source: arkema-7003
where: Mechanical properties table
- benchmark: elastic_modulus
label: Tensile modulus, Kepstan 8002
value: 3.8
unit: GPa
scope: material
conditions:
grade: KEPSTAN 8002 (medium flow, 8000 series)
test_standard: ISO 527-A12, 1 mm/min, 23 °C
method: Value in the 8000 series technical data sheet, mechanical table
status: ground
note: Per the same table, the 8001 grade is 3.6 GPa and the 8003 grade 4.1 GPa.
source: arkema-8000
where: Material properties table, Mechanical, Tensile modulus row
- benchmark: elastic_modulus
label: Tensile modulus, Kepstan 6002 (amorphous)
value: 2.9
unit: GPa
scope: material
conditions:
grade: KEPSTAN 6002 (amorphous)
test_standard: ISO 527-A12, 1 mm/min, 23 °C
state: amorphous injection-moulded
method: Value in the 6000 series technical data sheet, mechanical table
status: ground
source: arkema-6000
where: Material properties table, Mechanical, Tensile modulus row
- benchmark: elastic_modulus
label: Tensile modulus of printed PEKK (open-chamber FFF, amorphous top layer)
value: 1060.4
unit: MPa
scope: material
conditions:
specimen: FFF-printed PEKK C (ThermaX filament, 3DXTech; the paper says it is believed to be Kepstan 7002), amorphous top-layer specimens
test: tensile, N = 5
method: Mean of five specimens reported by the paper, Table 2
status: ground
uncertainty: standard deviation 30.6 MPa
note: Roughly a quarter of the 4000 MPa datasheet value for Kepstan 7003, so the printed part is far less stiff than injection-moulded material.
source: rodzen2025
where: Section 5.3 and Table 2
- benchmark: yield_strength
label: Tensile yield stress, Kepstan 7003
value: 110
value_high: 120
bound: range
unit: MPa
scope: material
conditions:
grade: KEPSTAN 7003 (injection-moulded specimens)
test_standard: ISO 527-1/-2 (1BA), 23 °C
method: Range in the manufacturer's technical data sheet, Mechanical properties table
status: ground
note: The 7000 series sheet prints 100 to 120 MPa for 7003 under the same heading, so the two Arkema sheets differ slightly.
source: arkema-7003
where: Mechanical properties table, Yield stress row
- benchmark: ultimate_tensile_strength
label: Tensile strength (maximum strength), Kepstan 8002
value: 116
unit: MPa
scope: material
conditions:
grade: KEPSTAN 8002 (injection-moulded specimens)
test_standard: ISO 527-A12, 23 °C
method: Value in the 8000 series technical data sheet, mechanical table
status: ground
note: Tensile strength of the 8001 grade is 110 MPa and the 8003 range 100 to 120 MPa on the same sheet.
source: arkema-8000
where: Material properties table, Mechanical, Tensile strength row
- benchmark: ultimate_tensile_strength
label: Tensile strength of printed PEKK (open-chamber FFF, amorphous top layer)
value: 93.9
unit: MPa
scope: material
conditions:
specimen: FFF-printed PEKK C (ThermaX filament, 3DXTech), amorphous top-layer specimens
test: tensile, N = 5
method: Mean of five specimens reported by the paper, Table 2
status: ground
uncertainty: standard deviation 5.5 MPa
note: The paper's abstract gives the same figure. Strain at break was 12.2 ± 1.5 % for these specimens.
source: rodzen2025
where: Abstract; Section 5.3 and Table 2
- benchmark: elongation
label: Elongation at break, Kepstan 7003
value: 3
value_high: 10
bound: range
unit: '%'
scope: material
conditions:
grade: KEPSTAN 7003 (injection-moulded specimens)
test_standard: ISO 527-1/-2 (1BA), 23 °C
method: Range in the manufacturer's technical data sheet, Mechanical properties table
status: ground
source: arkema-7003
where: Mechanical properties table, Nominal strain at break row
- benchmark: elongation
label: Elongation at break, Kepstan 8002
value: 20
unit: '%'
scope: material
conditions:
grade: KEPSTAN 8002 (injection-moulded specimens)
test_standard: ISO 527-A12, 23 °C
method: Value in the 8000 series technical data sheet, mechanical table
status: ground
note: The 8003 grade on the same sheet breaks at 3 to 10 %, so strain at break depends strongly on the flow grade.
source: arkema-8000
where: Material properties table, Mechanical, Elongation at break row
- benchmark: flexural_modulus
label: Flexural modulus, Kepstan 8002
value: 3.9
unit: GPa
scope: material
conditions:
grade: KEPSTAN 8002
test_standard: ISO 178, 23 °C
method: Value in the 8000 series technical data sheet, mechanical table
status: ground
source: arkema-8000
where: Material properties table, Flexural modulus row
- benchmark: flexural_strength
label: Flexural strength (maximum), Kepstan 8002
value: 180
unit: MPa
scope: material
conditions:
grade: KEPSTAN 8002
test_standard: ISO 178, 23 °C
method: Value in the 8000 series technical data sheet, mechanical table
status: ground
note: The same sheet gives 25 MPa for the 8002 grade at 175 °C, so the flexural strength drops sharply with heat.
source: arkema-8000
where: Material properties table, Flexural strength row
- benchmark: cte
label: Coefficient of thermal expansion, -100 °C to Tg, Kepstan 8002
value: 23
unit: µm/m/K
scope: material
conditions:
grade: KEPSTAN 8002
method_detail: DMA, tension, average from -100 °C to Tg
method: Value in the 8000 series technical data sheet, thermal table
status: ground
note: Above Tg and up to 300 °C the sheet gives 225 µm/m/K.
source: arkema-8000
where: Material properties table, Thermal, Coefficient of thermal expansion row
- benchmark: specific_heat
label: Specific heat capacity, Kepstan 7003
value: 1.02
unit: J/g/K
scope: material
conditions:
grade: KEPSTAN 7003
temperature: 23 °C
method: Value in the manufacturer's technical data sheet, Thermal properties table
status: ground
source: arkema-7003
where: Thermal properties table
- benchmark: moisture_absorption
label: Water absorption at equilibrium, 23 °C and 50 % RH, Kepstan 7003
value: 0.4
unit: '%'
scope: material
conditions:
grade: KEPSTAN 7003
test_standard: ISO 62, 23 °C, 50 % RH, equilibrium
method: Value in the manufacturer's technical data sheet, Other properties table
status: ground
note: At equilibrium in immersion the same sheet gives 0.7 %, and after 24 h in 50 % RH 0.05 % for a 2 mm specimen.
source: arkema-7003
where: Other properties table, Water absorption rows
- benchmark: dielectric_strength
label: Dielectric strength, 100 µm film, Kepstan 7003
value: 84
unit: kV/mm
scope: material
conditions:
grade: KEPSTAN 7003
test_standard: IEC 60243-1, 100 µm thickness
method: Value in the manufacturer's technical data sheet, Electrical properties table
status: ground
source: arkema-7003
where: Electrical properties table
- benchmark: dielectric_constant
label: Relative permittivity, 23 °C and 1 MHz, Kepstan 7003
value: 3
unit: '-'
scope: material
conditions:
grade: KEPSTAN 7003
test_standard: IEC 62631-2-1, 23 °C, 1 MHz
method: Value in the manufacturer's technical data sheet, Electrical properties table
status: ground
source: arkema-7003
where: Electrical properties table, Relative permittivity row
- benchmark: dissipation_factor
label: Loss tangent, 23 °C and 1 kHz, Kepstan 8002
value: 0.002
unit: '-'
scope: material
conditions:
grade: KEPSTAN 8002
test_standard: IEC 60250, 23 °C, 1 kHz
method: Value in the 8000 series technical data sheet, electrical table
status: ground
source: arkema-8000
where: Electrical table, Loss tangent row
- benchmark: limiting_oxygen_index
label: Limiting oxygen index, Kepstan 7003
value: 38
unit: '% O2'
scope: material
conditions:
grade: KEPSTAN 7003
test_standard: ISO 4589-1/-2, nominal thickness 3.2 mm
method: Value in the manufacturer's technical data sheet, Thermal properties table
status: ground
note: The same sheet gives burning behaviour of V-0 at a nominal thickness of 0.8 mm (IEC 60695-11-10).
source: arkema-7003
where: Thermal properties table, Limiting oxygen index row
- benchmark: charpy_notched_impact
label: Charpy notched impact strength, 23 °C, Kepstan 7003
value: 4.5
unit: kJ/m2
scope: material
conditions:
grade: KEPSTAN 7003
test_standard: ISO 179 1eA, 23 °C
method: Value in the manufacturer's technical data sheet, Mechanical properties table
status: ground
source: arkema-7003
where: Mechanical properties table, Charpy notched impact row
sources:
arkema-8000:
title: 'Technical Data: KEPSTAN 8000 Series (PEKK; 8001, 8002 and 8003)'
id: Arkema technical data sheet, Rev. Nov 2024
url: https://hpp.arkema.com/assets/arkema/TDS%20ARKEMA%20KEPSTAN%20serie%208000.pdf
year: 2024
kind: datasheet
license: manufacturer document, linked not reproduced
arkema-7000:
title: 'Technical Data: KEPSTAN 7000 Series (PEKK; 7001, 7002 and 7003)'
id: Arkema technical data sheet, Rev Nov 2024
url: https://hpp.arkema.com/assets/arkema/TDS%20ARKEMA%20KEPSTAN%20serie%207000.pdf
year: 2024
kind: datasheet
license: manufacturer document, linked not reproduced
arkema-6000:
title: 'Technical Data: KEPSTAN 6000 Series (pseudo-amorphous PEKK; 6001, 6002 and 6003)'
id: Arkema technical data sheet, Rev Nov 2024
url: https://hpp.arkema.com/assets/arkema/TDS%20ARKEMA%20KEPSTAN%20serie%206000.pdf
year: 2024
kind: datasheet
license: manufacturer document, linked not reproduced
arkema-7003:
title: 'KEPSTAN 7003: Polyetherketoneketone pellet or flake, technical data sheet'
id: Arkema HPP technical data sheet, footer dated 2026-09-29
url: https://hpp.arkema.com/assets/arkema/TDS_KEPSTAN%C2%AE%207003_en_WW.pdf
year: 2026
kind: datasheet
license: manufacturer document, linked not reproduced
arkema-8003:
title: 'KEPSTAN 8003: Polyetherketoneketone pellet or flake, technical data sheet'
id: Arkema HPP technical data sheet, footer dated 2026-09-29
url: https://hpp.arkema.com/assets/arkema/TDS_KEPSTAN%C2%AE%208003_en_WW.pdf
year: 2026
kind: datasheet
license: manufacturer document, linked not reproduced
rodzen2025:
title: Crystallization and microstructure effects on interlayer performance and ductility of Polyetherketoneketone in open-chamber fused filament fabrication
id: doi:10.1016/j.mtcomm.2025.114253 (Materials Today Communications 49, 114253)
url: https://pure.ulster.ac.uk/ws/files/235453217/1-s2.0-S2352492825027655-main.pdf
year: 2025
kind: paper
license: CC BY 4.0
glaskova2024:
title: The Tensile, Thermal and Flame-Retardant Properties of Polyetherimide and Polyetherketoneketone Processed via Fused Filament Fabrication
id: doi:10.3390/polym16030336 (Polymers 16(3), 336)
url: https://doi.org/10.3390/polym16030336
year: 2024
kind: paper
license: CC BY 4.0
note: 'Section 3 text of the open-access PDF: versus PEI, PEKK elastic modulus 18.2 % and tensile strength 6.0 % higher at 0 degree raster; at 45 degrees, elastic modulus 41.1 % and tensile strength 104.4 % higher. The paper gives relative figures only.'
garcia2021:
title: Characterization of polyaryletherketone (PAEK) filaments and parts printed by extrusion-based additive manufacturing
id: doi:10.1002/pi.6231 (Polymer International 70(8), 1128-1136)
url: https://researchdiscovery.drexel.edu/esploro/outputs/journalArticle/Characterization-of-polyaryletherketone-PAEK-filaments-and/991019168382304721
year: 2021
kind: paper
license: publisher record, linked not reproduced
note: 'Abstract, read through the publisher record: Tg of printed PEEK bars 146.8 °C against 154.8 °C for the parent PEEK filament; no observable difference between PEKK filament and printed bars.'
wiki-pekk:
title: Polyetherketoneketone (Wikipedia)
id: Wikipedia article, accessed 2026-10-26; history, manufacturer and infobox context only
url: https://en.wikipedia.org/wiki/Polyetherketoneketone
year: 2026
kind: web
license: CC BY-SA 4.0
license: CC-BY-4.0
updated: '2026-10-26'
review:
status: draft
method: assistant
checked_values: 27
unreachable: 1
caveats: 4
note: Written by an AI assistant on 2026-10-26. Values come from the Arkema datasheets and the Rodzen 2025 paper, read as text in this run. The 2016 CF/PEKK ageing paper (SAGE, 403) could not be opened; no Arkema SDS was found.
corrosion:
- environment: Water vapour and immersion at 23 °C
headline: PEKK takes up about 0.4 % water at 50 % humidity and 0.7 % in immersion, at equilibrium.
effect: Equilibrium water absorption is 0.4 % at 23 °C and 50 % relative humidity, and 0.7 % in immersion (ISO 62, KEPSTAN 7003). These are uptake figures; no wet-and-dry ageing test was read in this run.
rating: low
conditions:
grade: KEPSTAN 7003
test_standard: ISO 62
source: arkema-7003
where: Other properties table, Water absorption rows
- environment: Heat over service life
headline: No long-term heat-ageing test was found; the datasheets give short-term heat deflection and glass transition only.
effect: KEPSTAN 7003 has a heat deflection temperature of 164 °C at 1.8 MPa and a glass transition of 162 °C. For the 8002 grade the sheet gives a yield stress of 24 MPa at 175 °C in a short tensile test at 25 mm/min, which is not an ageing result.
rating: unknown
conditions:
basis: short-term tests on datasheets
source: arkema-8000
where: Thermal table (heat deflection rows); Mechanical table (tensile strength at HT rows)
- environment: Ultraviolet light
headline: No UV-ageing number for PEKK was read; the datasheet only asks for UV-protected storage.
effect: KEPSTAN 7003 gives an indefinite shelf life when stored sealed with appropriate UV protection and temperature. The 2016 carbon-fibre PEKK ageing paper (J. Thermoplastic Composite Materials, DOI 10.1177/0892705714564283) could not be opened (HTTP 403), so its UV findings are not used.
rating: unknown
conditions:
basis: storage statement only
source: arkema-7003
where: Shelf life section
- environment: Chemicals and solvents
headline: Arkema describes chemical resistance in general terms only; no chemical-resistance table was read.
effect: The 8000 series product description cites chemical and fire resistance from the semi-crystalline solid state. No acid, base or solvent test was read in this run.
rating: unknown
conditions:
basis: product description only
source: arkema-8000
where: Product description
risks:
hazards: []
failure_risks:
- mode: Brittle interlayer in printed PEKK
trigger: Top layer of a printed part allowed to crystallize (open-chamber FFF, no top-layer temperature control)
consequence: Excess crystallization causes brittleness through poor chain entanglement at the layer interface. The paper reports the tensile strength of the crystallized batch was reduced by about 49 % relative to the amorphous top layer.
severity: moderate
source: rodzen2025
where: Abstract; Section 5.3
- mode: Low stiffness of printed PEKK
trigger: Fused-filament printing of PEKK C filament, amorphous top layer, tensile test
consequence: Printed tensile modulus was 1060.4 MPa, against the 4000 MPa datasheet value for injection-moulded Kepstan 7003, so stiffness-critical printed parts need their own test data.
severity: moderate
source: rodzen2025
where: Table 2
- mode: Strength loss at elevated temperature
trigger: Tensile test at 175 °C (8002 grade, ISO 527-A12, 25 mm/min)
consequence: Tensile strength at the yield point falls to 24 MPa at 175 °C, against 116 MPa maximum strength at 23 °C, so a loaded part should stay well below this temperature.
severity: high
source: arkema-8000
where: Material properties table, Mechanical, Tensile strength (yield point) at HT row
side_effects: []
handling:
- text: 'Melt-process the 8000 series at 375 to 385 °C (extrusion and injection), and dry the resin first: 150 °C for 3 to 4 hours, or 120 °C for 6 to 8 hours.'
source: arkema-8000
where: Recommended processing conditions
- text: Store sealed, with UV protection and at a controlled temperature; the 7003 sheet gives an indefinite shelf life under those conditions.
source: arkema-7003
where: Shelf life section
mitigations:
- text: Keep the top layer below its crystallization threshold and control its temperature (halogen heater on an open-chamber printer) to keep ductility.
source: rodzen2025
where: Abstract
uses:
- application: structures
device: Fused-filament-printed PEKK parts from an open-chamber printer (ground tests only)
example: A PEKK C filament was printed without an enclosed chamber and reached 93.9 ± 5.5 MPa tensile strength in the amorphous-top-layer condition, with the authors claiming comparable results to enclosed systems.
source: rodzen2025
where: Abstract; Section 5.3
- application: structures
device: Continuous-fibre composites and filament printing with the 7000 series grades (manufacturer application statement)
example: Arkema says the 7000 series is 'highly enabling' for continuous fibre composites for structural applications and for filament additive manufacturing, with or without continuous fibres.
source: arkema-7000
where: Product description
supply:
- subject: PEKK polymer (Kepstan)
producers: []
source: arkema-8000
where: Arkema France, Colombes (France), named in the datasheet footer. No country shares for PEKK resin were read. Filament-grade PEKK C was bought from 3DXTech (Michigan, USA) per Rodzen 2025, Section 3.1.
documents:
- title: KEPSTAN 8000 Series technical data sheet (Rev Nov 2024)
type: datasheet
url: https://hpp.arkema.com/assets/arkema/TDS%20ARKEMA%20KEPSTAN%20serie%208000.pdf
year: 2024
- title: KEPSTAN 7000 Series technical data sheet (Rev Nov 2024)
type: datasheet
url: https://hpp.arkema.com/assets/arkema/TDS%20ARKEMA%20KEPSTAN%20serie%207000.pdf
year: 2024
- title: KEPSTAN 6000 Series technical data sheet (Rev Nov 2024)
type: datasheet
url: https://hpp.arkema.com/assets/arkema/TDS%20ARKEMA%20KEPSTAN%20serie%206000.pdf
year: 2024
- title: KEPSTAN 7003 technical data sheet
type: datasheet
url: https://hpp.arkema.com/assets/arkema/TDS_KEPSTAN%C2%AE%207003_en_WW.pdf
year: 2026
- title: KEPSTAN 8003 technical data sheet
type: datasheet
url: https://hpp.arkema.com/assets/arkema/TDS_KEPSTAN%C2%AE%208003_en_WW.pdf
year: 2026
- title: Crystallization and microstructure effects on interlayer performance and ductility of PEKK in open-chamber FFF (open access)
type: paper
url: https://pure.ulster.ac.uk/ws/files/235453217/1-s2.0-S2352492825027655-main.pdf
year: 2025
- title: The Tensile, Thermal and Flame-Retardant Properties of PEI and PEKK Processed via FFF (open access)
type: paper
url: https://doi.org/10.3390/polym16030336
year: 2024
- title: Characterization of PAEK filaments and parts printed by extrusion-based additive manufacturing
type: paper
url: https://researchdiscovery.drexel.edu/esploro/outputs/journalArticle/Characterization-of-polyaryletherketone-PAEK-filaments-and/991019168382304721
year: 2021
gaps:
- No media (images) were added to this profile; no PEKK picture with a checked licence was read in this run.
- No Arkema safety data sheet or PubChem GHS record for PEKK was read, so hazards is empty. The datasheets give no hazard classification and point to other documents.
- No CAS number is entered. The Wikipedia infobox gives 29658-26-2, but I could not confirm it for PEKK on a second page, and no PubChem record was found.
- No repeat-unit formula, monomer atoms or monomer supply was read; the recipe below uses the copolymer description only.
- No atomic-oxygen erosion, outgassing (ECSS), vacuum, radiation or flight result for PEKK was found. Search returned only PEEK and PEI flight records.
- No UV-ageing or long-term heat-ageing number for PEKK was read. The 2016 CF/PEKK ageing paper (J. Thermoplastic Composite Materials, DOI 10.1177/0892705714564283) returned HTTP 403 at SAGE, so only a search snippet was seen and it is not used.
- No country shares, feedstock source or critical-mineral listing for PEKK was found; only the Arkema head office is documented.
- PEK (polyetherketone) was not covered. The Victrex PEK search returned only PEEK grades 90G and 151G, which are PEEK, not PEK.
- The two Arkema sheets disagree on some values (7003 yield stress 110 to 120 MPa against 100 to 120 MPa on the 7000 series sheet; volume resistivity given in different units). Only the standalone 7003 values are entered for the 7003 grade, and the volume resistivity is left out.
- Printed PEKK values come from one filament (ThermaX PEKK C, believed to be Kepstan 7002, per the paper) and one printer, so they are not a datasheet grade.
- Garcia et al. 2021 (PEEK and PEKK printed parts) gave no PEKK numbers in its abstract, only the statement that printed PEKK shows no difference from the filament; its PEEK numbers are used only in the comparison text.
- limiting_oxygen_index and charpy_notched_impact are not canonical property names in property-canon.yaml; they are kept as snake_case names for this profile.
- Elevated-temperature strength is taken from one 8002 row (175 °C yield strength); no 125 °C or 175 °C value is entered as a benchmark.
- A 2026 FFF PEKK biomedical paper (UCL, Biomaterials Advances) is restricted to UCL staff until 12 August 2026 and was not read.
- The Kimya PEKK-A filament page returned no property table (behind a sign-in), so it is not used.
story:
recipe:
line: PEKK is a poly(aryl ether ketone ketone) copolymer. Arkema builds its Kepstan grades on a PEKK backbone with a high ketone content and a copolymer of terephthalic and isophthalic units, with the ratio setting crystallization speed (6000 series amorphous, 7000 and 8000 series semi-crystalline). The chain is stiff because of the aromatic rings and ketone links.
parts:
- name: Terephthalic moiety
symbol: T
role: Para-linked aromatic unit in the copolymer. It favours a more regular chain and faster crystallization.
- name: Isophthalic moiety
symbol: I
role: Meta-linked aromatic unit. It lowers crystallinity and slows crystallization, which is why the 6000 series is pseudo-amorphous.
- name: Ether and ketone links
symbol: O, CO
role: Ether links give flexibility of the chain; ketone links give the high-temperature stiffness.
risk_groups:
- title: For people
level: 0
verdict: Not classified in the sources read
lead: No Arkema safety data sheet was read, so there is no hazard classification for the resin, only processing guidance.
points:
- label: The resin
line: The datasheets describe handling and processing only. They give no toxicology or hazard statements, so treat the resin as unknown rather than safe.
- label: Melt
line: The 8000 series is processed at 375 to 385 °C, so hot polymer and fume from melting are a concern. The sources read do not give fume or burn data.
- title: If a part fails
lead: These results come from printed test coupons and datasheet tests, not from failures of finished parts.
points:
- label: Printed layers
line: When the top layer of a printed part crystallized, tensile strength fell by about 49 %, because the layer interface became brittle.
- label: Printed stiffness
line: Printed tensile modulus was 1060.4 MPa, far below the 4000 MPa of injection-moulded Kepstan 7003.
- label: Heat
line: Tensile strength at the yield point fell to 24 MPa at 175 °C for the 8002 grade, against 116 MPa maximum strength at 23 °C.
- title: Handling and storage
points:
- label: Drying
line: Dry the pellets before processing, at 150 °C for 3 to 4 hours or 120 °C for 6 to 8 hours.
- label: Storage
line: Keep the resin sealed and UV-protected; Arkema gives an indefinite shelf life under those conditions.
why: PEKK is a semi-crystalline thermoplastic in the PAEK family. Its ketone-rich chain and aromatic rings keep it stiff at high temperature, and the choice of terephthalic and isophthalic units sets how fast it crystallizes. That lets one family cover amorphous grades for low-temperature processing and semi-crystalline grades for stiffness. The Kepstan 7000 series is sold for filament printing, because its slower crystallization eases interlayer adhesion, and the same paper family reports that PEKK keeps no observable difference between filament and printed parts, while PEEK loses some glass transition on printing.
uses:
- where: Printed structural parts
line: Printed PEKK C filament reached a tensile strength of 93.9 MPa in an open-chamber printer, which the authors compare with enclosed systems. These are ground test coupons, not flight parts.
- where: Composite and filament structures
line: Arkema describes the 7000 series as highly enabling for continuous-fibre composite structures and for filament additive manufacturing. The datasheet does not name a specific part.
can_do:
- label: Stiffness
value: 4000 MPa
line: The 7003 grade has a tensile modulus of 4000 MPa and a yield stress of 110 to 120 MPa at 23 °C, from injection-moulded specimens. The printed PEKK in the Rodzen paper was far less stiff, at 1060.4 MPa.
- label: Heat
value: 162 °C glass transition
line: The 7003 grade has a glass transition of 162 °C and a heat deflection temperature of 164 °C at 1.8 MPa. The 8003 grade melts at 360 °C and has a glass transition of 165 °C.
- label: Fire
value: V-0 at 0.8 mm
line: The 7003 sheet gives a limiting oxygen index of 38 % and a V-0 rating at a nominal thickness of 0.8 mm (IEC 60695-11-10).
- label: Printed strength
value: 93.9 MPa
line: Printed PEKK C in the amorphous top-layer condition reached 93.9 ± 5.5 MPa tensile strength, with 12.2 ± 1.5 % strain at break.
compare: Against PEI, the Glaskova study found PEKK stiffer and stronger when printed at a 0 degree raster angle (18.2 % and 6.0 % higher in modulus and strength) and much stronger at 45 degrees (41.1 % higher modulus and 104.4 % higher tensile strength), with more uniform behaviour across print directions. Against PEEK, the Garcia 2021 study found that printed PEEK bars had a glass transition of 146.8 °C, about 8 °C below the 154.8 °C of the parent filament, while printed PEKK showed no observable difference from its filament. Arkema's 6000 series also states a high ketone content and a copolymer structure, which is how PEKK differs from PEEK in chemistry, but no PEEK value from the same run is used here.
compare_rows:
- label: Density
benchmark: density
- label: Melting point
benchmark: melting_point
- label: Tensile modulus
benchmark: elastic_modulus
handling:
- Dry the pellets before melt processing; 150 °C for 3 to 4 hours is the datasheet's first option.
- Keep the resin sealed and UV-protected in storage.
- Control the top-layer temperature of printed parts to keep the layer ductile.
- Do not use the datasheet numbers as design values for printed parts without test data.
good_for:
- Stiffness at temperature. The 7003 grade has a tensile modulus of 4000 MPa and a glass transition of 162 °C.
- Flame resistance. A limiting oxygen index of 38 % and V-0 at 0.8 mm.
- Printed parts with control. Printed PEKK reached 93.9 MPa when the top layer stayed amorphous.
watch_out:
- Printed stiffness. Printed PEKK had a tensile modulus of 1060.4 MPa against 4000 MPa for injection-moulded material.
- Crystallized top layers. Tensile strength fell by about 49 % when the top layer crystallized.
- Heat. Tensile strength at the yield point fell to 24 MPa at 175 °C for the 8002 grade.
- Ageing. No UV or long-term heat-ageing number for PEKK was found, so long service in sunlight or hot environments is untested.
verdict: PEKK is a stiff, flame-resistant, heat-tolerant thermoplastic with good datasheet properties, but the printed-part numbers are much lower than the datasheet. Test printed parts directly before using them in a load-bearing design, and treat any space use as untested.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.