FDM Part X High Temperature Polymers

FDM Polymers — A Technical Reference ›

Part X — High-temperature polymers

The high-temperature tier: PPS, the sulfones (PSU, PPSU), PEI, and the PAEK family. PPS-CF is the accessible end — routinely printable on Tier 3 prosumer hardware — while the sulfones and PEI sit at or beyond the Tier 3/4 boundary and PAEK is firmly Tier 4. Where a polymer is out of prosumer reach, these chapters say so explicitly rather than pretending otherwise.

18. PPS, PSU, PPSU, PEI

Four high-tem­per­a­ture en­gi­neer­ing poly­mers that share a hard­ware tier — Tier 3/Tier 4 bound­ary hard­ware (noz­zle 300–350 °C, bed 110–150 °C, active chamber 55 °C minimum where the grade specifies one (several PPS-CF products officially print without a heated chamber — see §18.1), >=65 °C for the sulfones, ≥85 °C for PEI (a 65 °C active chamber is demonstrated but marginal)) is manda­to­ry for any of them. The bed and noz­zle de­mands here reach past the §4 Tier 3 en­ve­lope (bed <=120 °C), so a fully Tier 3 ma­chine is the prac­ti­cal min­i­mum only for the lower-tem­per­a­ture grades; full Tier 4 (noz­zle 380–420 °C, cham­ber >=85 °C) is re­quired for un­filled PEI and the high-end PSU/PPSU grades. The poly­mers them­selves have near­ly noth­ing else in com­mon: PPS is semi-crys­talline with chem­i­cal re­sis­tance that ap­proach­es PEEK at sub­stan­tial­ly lower pro­cess­ing tem­per­a­tures; PSU and PPSU are amor­phous sul­fone poly­mers with hy­drolyt­ic sta­bil­i­ty and steam-ster­il­iza­tion com­pat­i­bil­i­ty; PEI is amor­phous with one of the high­est glass tran­si­tions of any amor­phous poly­mer reach­ing com­mer­cial fil­a­ment form (217 °C — above PSU, though just under PPSU) and in­trin­sic flame re­tar­dance.

Con­sumer ac­ces­si­bil­i­ty note. Open-spool filament for this polymer family is concentrated in CF-reinforced PPS and PEI products, but the unfilled grades are not absent from the open-spool market: 3DXTech sells ThermaX PSU and ThermaX PPSU at retail (~$125 per 500 g — see §18.2), and unfilled ULTEM ships open-spool from 3DXTech (ThermaX PEI 9085), Intamsys, and 3D4Makers, though sealed-cartridge industrial ecosystems (out of scope per Part I §1.2) still account for most unfilled-PEI volume. The consumer-accessible products in this chapter are PPS-CF (multiple brands), PEI (CF-reinforced and limited unfilled), and specialty-tier PSU/PPSU.

18.1 PPS (polyphenylene sulfide)

PPS is an aro­mat­ic en­gi­neer­ing poly­mer with a resin RTI of 200–220 °C (printed PPS-CF parts realistically 180–200 °C continuous), chem­i­cal re­sis­tance to vir­tu­al­ly every com­mon sol­vent and acid below 200 °C, in­trin­sic flame re­tar­dance to UL94 V-0 with­out ad­di­tives, and low mois­ture ab­sorp­tion. Semi-crys­talline, T_m ~280 °C, T_g ~90 °C, ten­sile strength 90–110 MPa (filled grades), mod­u­lus rough­ly 5–12 GPa for print­ed CF-filled grades (the 10%-CF con­sumer fil­a­ments sit near the bot­tom of that band — Poly­mak­er Fiberon PPS-CF10 re­ports about 5 GPa from print­ed spec­i­mens — while high­er-CF com­pounds reach into the low teens), HDT @ 1.8 MPa above 130 °C. The poly­mer for parts that load me­chan­i­cal­ly at 150–200 °C con­tin­u­ous, see fuels or oils, or re­quire flame re­tar­dance with­out halo­genat­ed ad­di­tives.

The CF-filled grades are es­sen­tial­ly the en­tire con­sumer mar­ket. Un­filled PPS is chal­leng­ing to print be­cause the rapid cool­ing be­tween de­posit­ed lay­ers below the poly­mer's crys­tal­liza­tion-onset tem­per­a­ture (~120 °C, re­quir­ing cham­ber tem­per­a­tures at the very top of Tier 3) pro­duces in­con­sis­tent crys­tallini­ty that com­pro­mis­es me­chan­i­cal per­for­mance. Car­bon-fiber re­in­force­ment at 10–20 wt% sup­press­es the crys­tal­liza­tion shrink­age, gives the matte black sur­face char­ac­ter­is­tic of CF-filled poly­mers, and pro­duces a print­able en­gi­neer­ing fil­a­ment. Hardened nozzles are mandatory for the CF abrasion; PPS adds a corrosive-wear component on tooling from sulfur-bearing decomposition species rather than any mechanical abrasion from the polymer itself.

Print process. Nozzle 320–350 °C; bed 80–120 °C; chamber product-dependent rather than family-wide — Polymaker Fiberon PPS-CF10 (bed 80–90 °C) and Flashforge PPS-CF officially print without a heated chamber, while Bambu PPS-CF specifies 60–90 °C; follow the spool TDS. Hardened steel nozzle (PCD preferred for production). Drying is likewise per spool TDS: Bambu specifies 100–140 °C for 8–12 h and Flashforge 120 °C for ≥8 h, so a generic 80–110 °C / 6–8 h cycle under-dries those grades. Bed adhesion: G10 garolite is the engineering default; Magigoo PA also works. On the chamber-spec'd grades, print at the upper end of the chamber range; below 50 °C chamber, interlayer adhesion falls off above ~80 mm Z-height. An­neal­ing at 200 °C for 2–4 h with packed-sand sup­port is rec­om­mend­ed for parts that will load at high tem­per­a­tures; the an­nealed crys­tallini­ty holds the heat en­ve­lope.

Brand land­scape. Bambu Lab PPS-CF (mid-2024 launch), Poly­mak­er Fiberon PPS-CF10 (10% CF load­ing doc­u­ment­ed), Flash­forge PPS-CF (LU­VO­COM com­pound), 3DX­Tech Car­bonX PPS+CF, and Raise3D In­dus­tri­al PPS-CF are among the more wide­ly avail­able con­sumer-ac­ces­si­ble prod­ucts. Pric­ing runs $150–280/kg. Poly­mak­er and 3DX­Tech pub­lish the most de­tailed TDS data; the Bambu prod­uct is the most vis­i­ble by com­mu­ni­ty adop­tion. PPS-CF is the right an­swer when the ap­pli­ca­tion loads above 150 °C con­tin­u­ous and PPA-CF (Chap­ter 14) is not enough.

18.2 PSU (polysulfone) and PPSU (polyphenylsulfone)

Poly­sul­fone (PSU) and polyphenyl­sul­fone (PPSU) are amor­phous en­gi­neer­ing poly­mers in the sul­fone fam­i­ly — char­ac­ter­ized by the sul­fone link­age (–SO₂–) in the poly­mer back­bone. Both have very high T_g (PSU ~185 °C, PPSU ~220 °C), ex­cep­tion­al hy­drolyt­ic sta­bil­i­ty (PPSU can survive many repeated steam-autoclave cycles when grade, stress state, and part design are appropriate), and trans­par­ent or amber-tint­ed op­ti­cal ap­pear­ance. The poly­mers be­hind med­i­cal in­stru­ments, air­craft cabin parts, and high-tem­per­a­ture plumb­ing fit­tings in in­dus­tri­al-scale man­u­fac­tur­ing.

Process re­quire­ments push above the pro­sumer en­ve­lope. PSU prints at 350–400 °C noz­zle, 140–155 °C bed, 65 °C cham­ber min­i­mum. PPSU prints at 370–410 °C noz­zle, 140–155 °C bed, 65 °C cham­ber. Both num­bers cross the upper edge of the Tier 3 en­ve­lope this vol­ume de­fines (350 °C noz­zle, 120 °C bed, 65 °C cham­ber). Con­sumer hard­ware that nom­i­nal­ly reach­es those tem­per­a­tures often does so un­sta­bly; re­li­able PSU/PPSU print­ing de­mands hard­ware that is also out of scope here. The poly­mer is in this chap­ter be­cause it ex­ists in the com­mer­cial fil­a­ment mar­ket and con­sumers ask about it, not be­cause it's a prac­ti­cal choice for pro­sumer FDM.

Brand land­scape. 3DX­Tech Ther­maX PSU and Ther­maX PPSU are the con­sumer-ac­ces­si­ble prod­ucts; pric­ing $250–500/kg. The re­al­is­tic pro­cure­ment path for PSU/PPSU parts is in­dus­tri­al out­sourc­ing or sealed-car­tridge in­dus­tri­al print­ers — both out­side this vol­ume's scope. For con­sumer users en­coun­ter­ing an ap­pli­ca­tion that calls for PSU or PPSU, the prac­ti­cal al­ter­na­tive is PPS-CF (for the heat en­ve­lope); for repeated autoclave service there is no prosumer-printable substitute — PC hydrolyzes under steam sterilization — so outsource the part or redesign around EtO or gamma sterilization.

18.3 PEI (polyetherimide / ULTEM-class)

Polyether­im­ide is an amor­phous high-tem­per­a­ture poly­mer best known under the SABIC ULTEM trade name — ULTEM 9085 and ULTEM 1010 are the two dom­i­nant grades in in­dus­tri­al FDM. Ten­sile strength 85–105 MPa, mod­u­lus 3.0–3.5 GPa, T_g 217 °C for 1010-class neat PEI (186 °C for the 9085 PEI/PC-copolymer blend), HDT @ 1.8 MPa ~153–190 °C (9085-class at the bottom of the range, 1010-class at the top), intrinsic flame retardance to UL94 V-0, very low smoke emis­sion dur­ing com­bus­tion (the char­ac­ter­is­tic that drives PEI's aero­space and rail-ve­hi­cle adop­tion). Amor­phous, so no crys­tal­liza­tion-re­lat­ed di­men­sion­al be­hav­ior to man­age — print­ed parts are di­men­sion­al­ly con­sis­tent.

Process re­quire­ments are firm­ly Tier 4. Unfilled and 1010-class PEI print at 370–420 °C nozzle, 140–155 °C bed, 85 °C minimum chamber; 9085-CF runs a lower nozzle (350–390 °C, Table 18.1) with the same 85 °C chamber floor — 65 °C active chambers are demonstrated but marginal. Dry­ing at 130–150 °C for 4–6 h is manda­to­ry — mois­ture at print tem­per­a­tures of 400 °C pro­duces cat­a­stroph­ic flash­ing in­side the melt zone. Hard­ware ca­pa­ble of these tem­per­a­tures sta­bly ex­ists but is not con­sumer-tier.

Con­sumer ac­ces­si­bil­i­ty. Open-spool PEI filament accessible to hobbyist users includes CF-reinforced grades — 3DXTech's ship under the CarbonX name (CarbonX PEI 9085+CF), not ThermaX, which 3DXTech reserves for unfilled grades — and unfilled ULTEM from 3DXTech (ThermaX PEI 9085), Intamsys, and 3D4Makers. Sealed-cartridge industrial ecosystems (out of scope) still account for most unfilled-PEI volume. For ap­pli­ca­tions that re­quire true PEI per­for­mance (UL94 V-0 with high heat en­ve­lope, aero­space cer­ti­fi­ca­tions, low-smoke com­bus­tion), the prac­ti­cal pro­cure­ment path for con­sumer users is in­dus­tri­al out­sourc­ing rather than in-house print­ing. PEI is in this vol­ume pri­mar­i­ly for con­text and to set the bound­ary of what pro­sumer FDM can and can­not reach.

18.4 Consolidated comparison

Polymer	Crystallinity	Tg(°C)	Continuous service (°C)	Nozzle (°C)	Consumer access
PPS-CF	Semi-crystalline	90	180–200	320–350	Mainstream consumer; multiple brands
PSU	Amorphous	185	150–170	350–400	Specialty only (3DXTech); above prosumer envelope
PPSU	Amorphous	220	180–200	370–410	Specialty only (3DXTech); above prosumer envelope
PEI 9085-CF	Amorphous	186	170	350–390	Specialty (3DXTech); straddles the Tier 3 / Tier 4 boundary
PEI 1010-CF	Amorphous	217	~170 (RTI)	370–420	Specialty (3DXTech); Tier 4 hardware required
PEI unfilled	Amorphous	217	~170 (RTI)	370–420	Open-spool from 3DXTech, Intamsys, 3D4Makers; Tier 4 hardware required; most volume remains sealed-cartridge industrial

_{Table 18.1 — High-tem­per­a­ture en­gi­neer­ing poly­mer fam­i­ly at a glance. PPS-CF is the only poly­mer in this group that prints re­li­ably on Tier 3 pro­sumer hard­ware; ev­ery­thing else ei­ther re­quires Tier 4 hard­ware or is locked to in­dus­tri­al-car­tridge ecosys­tems. For con­sumer users with ap­pli­ca­tions in this ther­mal en­ve­lope, PPS-CF is the prac­ti­cal en­gi­neer­ing an­swer; PEI and the sul­fones are as­pi­ra­tional un­less in­dus­tri­al hard­ware or out­sourc­ing is on the pro­cure­ment path.}

19. PAEK family (PEEK, PEKK)

The pol­yarylether­ke­tone (PAEK) fam­i­ly is the apex of FDM ther­mo­plas­tics: con­tin­u­ous-ser­vice tem­per­a­tures around 250 °C, high strength-to-weight at much lower density than metals, chem­i­cal re­sis­tance ap­proach­ing PTFE, and — in im­plant-grade resin for­mu­la­tions — a bio­com­pat­i­bil­i­ty record be­hind decades of cleared med­i­cal de­vices. PAEK parts can replace aluminum where heat, chemistry, weight, and specific strength matter more than absolute stiffness; they do not match aluminum's elastic modulus, and FDM parts remain anisotropic and crystallinity-dependent. PEEK (polyetherether­ke­tone) is the vol­ume lead­er; PEKK (polyether­ke­toneke­tone) ex­ists in amor­phous and semi-crys­talline vari­ants with somewhat lower or grade-dependent T_m. The polymer family is used for engineering metal-replacement in aero­space, au­to­mo­tive, oil-and-gas, and med­i­cal ap­pli­ca­tions when those trade-offs are acceptable.

This chap­ter ex­ists to bound the vol­ume's scope rather than en­able con­sumer PAEK print­ing. PAEK pro­cess­ing re­quires noz­zle 380–440 °C, bed 140–155 °C, ac­tive cham­ber >=85 °C, dry­ing at 120–130 °C, and post-print an­neal­ing for crys­tallini­ty. Every line item ex­ceeds the Tier 3 pro­sumer en­ve­lope this vol­ume cov­ers. Con­sumer-tier FDM hard­ware la­beled as PEEK-ca­pa­ble typ­i­cal­ly reach­es the noz­zle tem­per­a­ture briefly and un­sta­bly, lacks the ac­tive cham­ber that PEEK crys­tallini­ty de­mands, and pro­duces parts whose me­chan­i­cal per­for­mance is a frac­tion of the in­dus­tri­al stan­dard. Con­sumer PAEK print­ing is pos­si­ble on small parts with sub­stan­tial caveats; re­li­able PAEK print­ing is not. Hob­by­ists who need PEEK parts al­most uni­ver­sal­ly find in­dus­tri­al out­sourc­ing the prac­ti­cal pro­cure­ment path.

19.1 PEEK (polyetheretherketone)

Semi-crys­talline. T_g 143 °C, T_m 343 °C, ten­sile strength 90–100 MPa (un­filled), 130–170 MPa (CF-filled), mod­u­lus 3.5–4.0 GPa un­filled and up to 12–15 GPa for CF-filled grades, con­tin­u­ous ser­vice tem­per­a­ture 240–250 °C. The poly­mer chem­istry has been industrially established since the early 1980s (synthesized 1978, commercialized 1981); the FDM-spe­cif­ic com­pound­ing (fil­a­ment-grade resin pro­cess­ing, di­am­e­ter tol­er­ance, mois­ture pro­tec­tion) is a more re­cent de­vel­op­ment.

Crys­tallini­ty is the dom­i­nant print­ed-part vari­able. Rapid cool­ing dur­ing FDM de­po­si­tion pro­duces par­tial­ly amor­phous PEEK with me­chan­i­cal per­for­mance well below the resin spec. Ac­tive cham­ber tem­per­a­tures of 150–200 °C dur­ing print­ing — in­dus­tri­al-tier ter­ri­to­ry — pro­duce semi-crys­talline parts with the full PEEK en­ve­lope. Cham­ber tem­per­a­tures of 85–110 °C (already above the 65 °C Tier 3 chamber ceiling — entry-level Tier 4 territory) pro­duce in­ter­me­di­ate re­sults that still re­quire post-print an­neal­ing (140–200 °C for 2–4 hours) to de­vel­op full crys­tallini­ty. The an­neal­ing step shrinks the part 1–3% and can warp thin walls.

19.2 PEKK (polyetherketoneketone)

PEKK is a PAEK fam­i­ly mem­ber dif­fer­en­ti­at­ed by molec­u­lar struc­ture — a dif­fer­ent ratio of ether link­ages to ke­tone link­ages along the back­bone. Com­mer­cial PEKK ex­ists in two prin­ci­pal vari­ants: PEKK-A (amor­phous, T_g ~165 °C, no T_m, pro­cess­es amor­phous­ly and stays amor­phous) and semi-crys­talline PEKK (T_g ~165 °C, T_m ~310–340 °C de­pend­ing on grade, de­vel­ops crys­tallini­ty on cool­ing and dur­ing an­neal­ing). Amor­phous PEKK pro­cess­es more eas­i­ly than PEEK be­cause it does not re­quire ac­tive cham­ber crys­tal­liza­tion; semi-crys­talline PEKK be­haves sim­i­lar­ly to PEEK in print­ing. PEKK is the prac­ti­cal PAEK-fam­i­ly choice for print­ers that can­not reach PEEK's process tem­per­a­tures sta­bly.

19.3 Consumer accessibility and brand landscape

Open-spool PAEK fil­a­ment ac­ces­si­ble to hob­by­ist users clus­ters around a small set of spe­cial­ty ven­dors:

Brand	Products	Notes
3DXTech	ThermaX PEEK; ThermaX PEKK-A (unfilled); CarbonX PEEK+CF; CarbonX PEKK-A+CF15	The US specialty leader for consumer-accessible PAEK; ISO 9001; comprehensive published TDS; pricing $300–500/kg
Polymaker	Fiberon PA12-CF10, formerly PolyMide PA12-CF (positioned as PEEK alternative)	Polymaker does not currently ship a true PAEK product; targets the application space with reinforced polyamide
Flashforge / specialty Asian	PEEK / PEEK-CF (limited)	Available but TDS documentation thin; pricing competitive but mechanical envelope variable
Generic Chinese specialty	PEEK / PEEK-CF	Budget tier with substantial quality variance; mechanical envelope below specialty leaders; appropriate for prototyping only

_{Table 19.1 — Con­sumer-ac­ces­si­ble PAEK fil­a­ments. The re­al­is­tic pro­cure­ment path for hob­by­ist PAEK ap­pli­ca­tions is 3DX­Tech Ther­maX PEEK-CF or PEKK-CF on hard­ware that meets the Tier 4 en­ve­lope. Sealed-car­tridge in­dus­tri­al PAEK ecosys­tems (Strata­sys F900 with PEKK, in­dus­tri­al Roboze with PEEK) are out of scope. Treat con­sumer PAEK as a niche spe­cial­ty fil­a­ment ac­ces­si­ble only to users who have in­vest­ed in the sup­port­ing hard­ware tier.}

19.4 Application fit

Choose PEEK when: the ap­pli­ca­tion re­quires con­tin­u­ous ser­vice above 200 °C with full me­chan­i­cal per­for­mance; the part will be made from an im­plant- or med­i­cal-grade PEEK resin through a qual­i­fied, val­i­dat­ed process where bio­com­pat­i­bil­i­ty is a re­quire­ment; chem­i­cal re­sis­tance and ther­mal en­durance to­geth­er ex­ceed what PPS-CF can de­liv­er; and the sup­port­ing hard­ware tier is avail­able. Choose PEKK when: the ap­pli­ca­tion tol­er­ates PEKK's slight­ly lower ther­mal en­ve­lope (typ­i­cal 220–240 °C con­tin­u­ous vs PEEK's 250 °C); amor­phous PEKK-A is ac­cept­able be­cause post-print crys­tal­liza­tion is op­er­a­tional­ly dif­fi­cult — the case for PEKK is process simplicity (amorphous-grade handling, relaxed crystallization discipline) rather than cost; PEKK filament typically prices above PEEK.

A cau­tion on med­i­cal and im­plant claims. PEEK's bio­com­pat­i­bil­i­ty record be­longs to spe­cif­ic im­plant-grade resin grades used in cleared, val­i­dat­ed de­vice work­flows — not to PEEK fil­a­ment gener­i­cal­ly. The first FDA-cleared 3D-print­ed PEEK im­plant was cleared as a com­plete sys­tem: a named im­plant-grade resin, a spec­i­fied print­er, de­fined mod­el­ing soft­ware, and a pre-val­i­dat­ed pro­duc­tion process, with full lot trace­abil­i­ty and post-build test­ing. Reg­u­la­to­ry clear­ance at­tach­es to that de­vice and process, and is grant­ed de­vice-by-de­vice. A part print­ed from or­di­nary PEEK fil­a­ment on pro­sumer hard­ware is not an im­plant and car­ries no bio­com­pat­i­bil­i­ty sta­tus; treat any med­i­cal-con­tact use as re­quir­ing its own qual­i­fi­ca­tion against the rel­e­vant stan­dards (e.g. ISO 10993) and reg­u­la­to­ry path­way.

For most con­sumer users: PPS-CF (Chap­ter 18), PPA-CF (Chap­ter 14), or PA6-CF (Chap­ter 13) al­most cer­tain­ly meets the ap­pli­ca­tion re­quire­ment at a frac­tion of the cost and process dis­ci­pline. The PAEK fam­i­ly is the right an­swer when the ap­pli­ca­tion re­quire­ment is gen­uine­ly above what those poly­mers can de­liv­er, and that bound­ary is high: con­tin­u­ous ser­vice above 200 °C, au­to­clave com­pat­i­bil­i­ty, cer­tain bio­com­pat­i­bil­i­ty cer­ti­fi­ca­tions. Below that bound­ary, choos­ing PAEK is over-en­gi­neer­ing.

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