PEKK (Polyetherketoneketone)

polymer

semi-crystalline high-performance aromatic thermoplastic (PAEK family)

PolyetherketoneketoneArkema Kepstan® PEKKKepstan 6002Kepstan 7002Stratasys Antero 800NAStratasys Antero 840CN03Oxford Performance Materials OPM100Solvay KetaSpire KT (PEEK-related)

Density

1.30 g/cm³

YS (FDM as-printed (XY) — Kepstan 6002 grade)

80–98 MPa

UTS (FDM as-printed (XY) — Kepstan 6002 grade)

82–102 MPa

Elongation (FDM as-printed (XY) — Kepstan 6002 grade)

1.8–4.0 %

Elastic modulus

4–4 GPa

Thermal conductivity

0.3 W/m·K

Glass transition (Tg)

150–162 °C

Max service temp

240–260 °C

Mechanical & thermal properties — 3 conditions

Property	FDM as-printed (XY) — Kepstan 6002 grade	FDM annealed 200°C/2h (XY) — increased crystallinity	SLS as-printed (Kepstan 7001/7002 grade) — near-isotropic
Elastic modulus	4–4 GPa	4–5 GPa	4–5 GPa
Yield strength (0.2%)	80–98 MPa	87–106 MPa	78–96 MPa
Ultimate tensile strength	82–102 MPa	90–112 MPa	82–100 MPa
Elongation at break	1.8–4.0 %	—	1.5–3.8 %
Density	1.27–1.33 g/cm³	—	1.27–1.33 g/cm³
Thermal conductivity	0.3 W/m·K	—	—
Glass transition (Tg)	150–162 °C	—	150–162 °C
Max service temperature	240–260 °C	—	240–260 °C

Values shown as min–max where a spread is reported, otherwise as typical ± unit. Ranges reflect inter-source variation, not single-sample scatter. All values are for AM-processed specimens unless noted.

Engineering considerations

Grade selection is critical: Kepstan 6002 (60/40 T/I, slow-crystallising) for FDM; Kepstan 7001 (70/30 T/I, faster-crystallising) for SLS. Using the wrong grade for the process produces poor part quality — verify grade with Arkema or Stratasys material specification before ordering.
Annealing recommendation: anneal FDM PEKK at 200°C/2h in a circulating-air oven (free-standing or lightly fixtured). Crystallinity increases from ~10–15% to ~20–28%, improving stiffness ~10%, HDT ~9°C, and fatigue resistance. Standard practice for structural and medical applications.
Comparison with PEEK: if SLS near-isotropy is required and PEEK HP3 is unavailable or too expensive, SLS PEKK (Kepstan 7001) is the natural alternative. For FDM applications where Z-direction strength is critical, PEKK outperforms PEEK FDM. If absolute maximum service temperature (>280°C) is needed, only PEEK is suitable.
Medical applications: use Kepstan biocompatible grades (PEKK-C, per ISO 10993-1 test programme). Verify FDA 510(k) status for implantable use — OPM OPM100 has cleared this pathway for spinal interbody devices. Document sterilisation cycle compatibility (gamma, EtO, autoclave).
ESD/static dissipation: for electronics and semiconductor applications, specify Antero 840CN03 (10% CF, ESD-safe) or equivalent CF-PEKK grade. Pure PEKK is an insulator (resistivity >10¹⁶ Ω·cm) — suitable for electrical insulation but not static-sensitive environments.
Dimensional change on annealing: expect 0.3–0.8% linear shrinkage during 200°C/2h annealing as crystallinity develops. Account for this in pre-anneal dimensions or iterate on a test print before production run.
Chemical resistance: PEKK has excellent resistance to organic solvents, acids (except concentrated H₂SO₄), and hydrocarbons — comparable to PEEK. Verify compatibility for extended immersion in specific chemicals; PEKK resistance data is less comprehensive than PEEK in published literature.

Advantages

Lower crystallisation rate than PEEK → superior FDM interlayer bonding: Z-direction strength ~75–80 MPa vs PEEK FDM Z ~50–65 MPa
Lower FDM processing temperature than PEEK (355°C vs 400°C) — accessible on a wider range of high-temperature FDM systems (Apium, Thought3D, some desktop HT machines)
Near-isotropic in SLS — avoids the severe Z-direction weakness of FDM PEEK and PEKK
Higher Tg than PEEK (155°C vs 143°C) — superior performance in applications just above 143°C
CF-PEKK FDM grades available (Antero 840CN03 with 10% short CF): improves stiffness and ESD/static dissipation for electronics manufacturing
Good biocompatibility — Arkema Kepstan grades have ISO 10993 data; suitable for medical device components
UL94 V-0 without additives — inherent flame retardance for aerospace and industrial applications
Can be post-annealed to increase crystallinity ~10–13%, improving stiffness and HDT

Limitations

SLS PEKK still requires high-temperature systems (~260–290°C chamber) — not compatible with standard PA12 SLS machines
FDM PEKK requires high-temperature printers (nozzle ~360°C, chamber ~150–180°C) — not compatible with standard desktop FDM
Properties still below injection-moulded PEKK (~80–85% of IM values) — crystallinity deficit limits maximum achievable performance
Lower melting point than PEEK (Kepstan 6002 ~305°C vs PEEK ~340°C) — reduces maximum upper service temperature margin
High material cost: comparable to PEEK powder/filament (~3–5× PA12). The PEKK grade (6002 vs 7001) must be matched to the process — specifying wrong grade risks processing failure
Limited machine ecosystem for SLS PEKK: fewer qualified systems than SLS PEEK (EOS P 800 is the primary platform)
Anisotropy in FDM remains significant: even with better interlayer bonding than PEEK, Z-direction is still 15–25% weaker than XY — FDM PEKK is not isotropic
Limited long-term fatigue and creep data for LPBF/FDM PEKK vs PEEK: less published literature makes conservative design necessary

Typical applications

Aerospace structural brackets and housings (FAR 25.853 FST compliance achievable)FDM spinal cage and orthopaedic device prototyping and production (biocompatible grades)Autoclave-sterilisable surgical instrument handles and components (134°C, 3 bar)Satellite and spacecraft structural components (low outgassing, thermal stability)Oil & gas downhole sensor housings and seals (chemical resistance, 200°C+ service)High-performance electrical connector bodies and insulator componentsSemiconductor handling fixtures (clean-room compatible, low particle generation)Industrial jigs and fixtures for composite lay-up and autoclave toolingCF-PEKK FDM for high-stiffness lightweight structures where CF-PEEK SLS is unavailable