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PPS (polyphenylene sulfide) and PEEK (polyetheretherketone) are both semi-crystalline, high-temperature thermoplastics with excellent chemical resistance — and each holds a clear advantage the other does not. PPS offers the broader chemical inertness in acids, bases and solvents, continuous service of 200–240°C (typical), and a material cost of roughly a third to a half of PEEK; its limits are a ~90°C glass transition, low unfilled ductility, and no short-term peak headroom above its rating. PEEK offers a 143°C glass transition, 260°C continuous service with 300°C short-term peaks, high toughness, and strong hydrolysis and wear performance; its limits are a substantially higher price and a chemical-resistance profile that, while excellent, is not wider than PPS's. Neither material is "better": they optimize for different requirement sets.
This comparison keeps to that framing. Every section below states what each material does well, where each falls short, and which numbers separate them — so the trade-offs can be matched against your own application rather than against a vendor's preference.
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PPS is the chemical-resistance and value specialist: best-in-class inertness to acids, bases and organic solvents, 200–240°C continuous service (typical), stable electrical properties, and a price around a third to half of PEEK. Its trade-offs: a ~90°C glass transition, brittle unfilled behavior (~2–4% elongation), and wear capability that depends heavily on fillers.
PEEK is the high-temperature structural benchmark: 143°C glass transition, 260°C continuous service with 300°C short-term peaks, ~25–30% elongation (tough, impact-tolerant), superb hydrolysis resistance, and strong bearing and wear capability especially in filled grades. Its trade-offs: a multiple of PPS's price, and chemical resistance that is excellent but not broader than PPS's.
Compare grades, not just polymers: glass fiber changes both materials dramatically — filled PPS HDT approaches 260°C but stays brittle and keeps its 90°C glass transition; filled PEEK keeps its toughness. The grade tables matter as much as the polymer names.
| Property | PEEK (unfilled) | PEEK GF30 | PPS (unfilled, typical) | PPS GF40 |
|---|---|---|---|---|
| Melting point (Tm) | 343°C | 343°C | 278°C | ~280°C |
| Glass transition (Tg) | 143°C | 143°C | ~90°C | ~90°C |
| Continuous service | 260°C (300°C short-term) | 260°C (300°C short-term) | 200–240°C | 200–240°C |
| HDT (1.8 MPa, unfilled) | 152°C | 315°C | 105°C | 265°C |
| Tensile strength | 100 MPa | 175 MPa | 85 MPa | 170MPa |
| Flexural modulus | 4.1 GPa | 11GPa | 3.9 GPa | 10.5GPa |
| Ductility | Tough (elongation ~45%) | 2.7% | 8% | 1.9% |
| Relative price | $$$$$ | $$$$$ | $$ (~1/3–1/2 of PEEK) | $$ (~1/3–1/2 of PEEK) |
PEEK values are PRES stock-grade data. PPS data are Torelina A900(Unfilled),Torelina 1130A64 (30% Glass-filled grades)
PPS — advantages: widest chemical inertness among engineering thermoplastics (acids, bases, fuels, solvents); stable dielectric properties across temperature; inherently flame-retardant without additives; low cost per kg and mature, high-volume injection molding supply; very low moisture uptake.
PPS — limitations: glass transition near 90°C caps self-supporting stiffness under sustained hot loads; unfilled grades are brittle (elongation 8%) and can crack on impact; unfilled wear and bearing capability is limited; continuous ratings (200–240°C, grade-dependent) carry little short-term peak headroom; stock shapes are less widely held than PEEK.
PEEK — advantages: highest structural temperature headroom in mainstream use (260°C continuous, 300°C peaks, Tg 143°C); tough and impact-tolerant (elongation ~25–30%); outstanding hydrolysis resistance in superheated water and steam; strong wear, bearing and sealing performance, especially in bearing and carbon-filled grades; excellent machinability with tight tolerances after annealing.
PEEK — limitations: material cost several times that of PPS, which dominates economics in high-volume molded parts; chemical resistance, while excellent, is not broader than PPS's outside hydrolysis; unfilled wear performance still benefits from fillers; melt processing demands high tooling temperatures (~380°C+), which narrows the field of molders.
On paper the service gap is 20–60°C depending on grade. The more decisive number is the glass transition: PPS softens structurally above ~90°C (typical), PEEK above 143°C. Below its Tg a semi-crystalline polymer still behaves as a rigid solid; above it, stiffness drops sharply. That is why unfilled PPS has an HDT around 110°C against PEEK's 152°C, and why glass-filled PPS — despite HDT readings near 260°C — still behaves as a filled composite rather than a self-supporting high-temperature plastic at those levels. PEEK's 260°C continuous rating also survives 300°C short-term peaks; PPS ratings do not include that headroom. For duty that stays under 200°C, both materials are comfortably inside their range — the gap only becomes decisive above it.
For PEEK's thermal numbers in isolation — melting point, HDT by grade, continuous ratings — the walkthrough is in our PEEK chemical and high temperature resistance guide.
Unfilled, the room-temperature strength numbers are close — 100 vs ~85 MPa tensile, 4.1 vs ~3.8 GPa flexural. The meaningful difference is behavior under temperature and time, and it runs in both directions. PEEK's higher Tg keeps it stiff under sustained load at heat, and its 45% elongation makes it impact-tolerant: a dropped part dents rather than cracks — an advantage in thin-wall machined parts and handling-intensive assembly. Unfilled PPS trades that toughness for rigidity and dimensional stability, which suits precision electrical and fluid components that see chemical exposure but little mechanical abuse; a dropped or impact-loaded PPS part is the scenario where its brittleness shows. Glass-fiber fillers close much of the static strength gap for PPS (see our 40% glass-filled PPS data), but they make it stiffer and more brittle, and do not change its low-Tg behavior under sustained hot loads. For rotating or wearing parts — bearings, bushings, wear rings, seals — filled PEEK grades carry the stronger data set; the wear test data is in our bearing grade vs CF30 comparison.
Both plastics are chemical-resistant heavyweights, and each leads in a different domain. PPS is arguably the single best engineering thermoplastic against acids, bases, fuels and organic solvents — its sulfur backbone simply does not react with much. The full PPS data set is on our PPS material page. PEEK leads in hydrolysis: in superheated water and steam above 200°C, PEEK holds its properties while many chemically excellent resins (including PPS in some conditions) degrade. In practice the two domains overlap heavily — both resist most solvents, both fail only against a short list of strong oxidizers — and the split only matters at the edges: strong chemicals below ~150°C sit in PPS's strongest territory; steam, hot water and repeated sterilization sit in PEEK's. Verify your exact medium against the producer's TDS either way.
PPS typically costs a third to a half of PEEK — the widest quality-per-dollar gap in the high-performance tier — and it reflects more than cheapness: decades of volume production, mature compounding, and melt processing at temperatures ordinary molding shops already run. That makes PPS the natural fit for high-volume molded parts — pump housings, sensor bodies, lamp sockets, fluid handling — where its per-part economics compound. We supply injection molding grades as PPS pellets for exactly this case.
PEEK's premium buys its temperature headroom, toughness and wear life, and its supply chain differs in kind: it is our core extrusion line with deep rod, sheet and PEEK material inventory for machined prototypes and low-volume parts. For machined stock shapes, one practical asymmetry worth planning around: PEEK stock is broadly held, while PPS stock shapes are thinner on the ground — see what we carry in PPS sheet before committing a machining project to it. On machining itself, neither is difficult: PEEK cuts with rigid chips and holds tolerances after annealing, while unfilled PPS is brittle at the cutting edge and glass-filled PPS is abrasive on tooling — sharp carbide, light passes and good support cover it.
The requirement sets that point toward PPS are the mirror image of those that point toward PEEK — neither list is longer or more legitimate than the other:
PPS fits requirement sets where continuous temperature stays below ~200°C, chemical exposure dominates the specification, electrical stability matters, and the part is molded in volume — its cost advantage does the rest.
PEEK fits requirement sets with sustained loads above 150°C, service at 240–260°C with short peaks to 300°C, steam or superheated water, wear or sealing duty, or impact-loaded thin-wall parts — its temperature and toughness headroom does the rest.
For the deeper numbers behind either column: PEEK's grade-by-grade property tables are in our PEEK material selection guide, the premium is unpacked in our PEEK price per kg guide, and PPS's full profile is on our PPS material page linked above.
Q1: Is PPS cheaper than PEEK?
A: Yes, typically a third to a half of PEEK's price, and the gap widens for glass-filled molded volumes. The lower price reflects decades of volume production rather than lower quality — PPS is the correct economic choice for high-volume parts within its temperature and toughness envelope.
Q2: Can PPS replace PEEK in my part?
A: It depends on which requirement dominates. If continuous temperature stays under ~200°C, loads are light or carried by glass fiber, and there is no steam, wear or impact requirement, PPS delivers the function at half the material cost. If the part carries load above 150°C, sees steam or wear duty, or must survive impact, those requirements sit outside PPS's envelope and PEEK is the match. Listing the requirements side by side settles it faster than any general rule.
Q3: Which is more chemically resistant, PPS or PEEK?
A: Each leads in a different domain: PPS has the edge against acids, bases, fuels and solvents; PEEK leads in superheated water, steam and repeated sterilization. Against most media — solvents, oils, mild reagents — both perform at the same high level, and both fail only against a short list of strong oxidizers. Verify your exact medium against the producer's TDS.
Q4: What temperature can PPS withstand?
A: Unfilled PPS serves continuously at 200–240°C (typical, grade-dependent), with a melting point near 280°C and a glass transition around 90°C. Under sustained mechanical load the practical ceiling is lower — near the 110°C unfilled HDT. Glass-filled grades read far higher on HDT (toward 260°C) but the load-bearing margin still comes from the fiber, not the base resin.
Q5: Do glass-filled grades change the comparison?
A: Significantly. Glass fiber lifts PPS stiffness and HDT dramatically but adds brittleness and does not raise the 90°C glass transition. Filled PEEK grades follow the same logic while keeping their toughness — our stock list covers GF30 and CF30. The practical takeaway is the same for both: compare the grade data sheets, not just the polymer names.
Q6: Why is PEEK so much more expensive than PPS?
A: Monomer and polymerization costs: PEEK is built from high-purity intermediates and polymerized in small-batch, tightly controlled processes at ~380°C+ melt temperatures, while PPS benefits from decades of volume production. The premium corresponds to specific properties — the 143°C glass transition, 260°C structural service, and the toughness and wear life that come with them — which matter only when your requirements use them.
Q7: Which machines better, PPS or PEEK?
A: Both machine well within their working styles. PEEK cuts with rigid chips, holds tolerances after annealing, and its toughness resists chipping on thin walls. Unfilled PPS is brittle at the cutting edge and glass-filled PPS is abrasive on tooling, so it wants sharp carbide, light passes and careful support — with those settings it machines to fine tolerances too. For thin-wall or deeply profiled parts, PEEK's toughness gives it more margin.
Q8: Do you really sell both?
A: Yes — PEEK is our core line with PPS, PEI and PPSU alongside, all extruded and machined in-house. That is why this comparison states the strengths and limits of both materials plainly: the right answer is whichever matches your requirement set.
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