PPS Ryton Properties — Mechanical, Thermal & Chemical
PPS (polyphenylene sulfide) delivers a combination of properties that is difficult to match at its price point: a continuous-use temperature of 425°F (218°C), near-universal chemical resistance below 392°F, water absorption of only 0.02%, and an inherent UL 94 V-0 flame rating. This page provides the full mechanical, thermal, chemical, and electrical property dataset needed to evaluate PPS Ryton against your application requirements.
At a glance:
- Tensile strength 13,000 psi (unfilled); glass-filled grades reach 18,000–19,000 psi
- Flexural modulus 600,000 psi unfilled; GF-33 grades reach ~2,000,000 psi
- Continuous service 425°F (218°C); short-term peaks tolerable above that
- Water absorption 0.02% — one of the lowest of any engineering thermoplastic
- Resists essentially all acids, bases, and organic solvents below 392°F
- Dielectric strength approximately 500 V/mil
- Density 1.35 g/cc — substantially lighter than aluminum (2.7 g/cc)
Mechanical Properties
Tensile and Compressive
Unfilled PPS exhibits tensile strength of 13,000 psi at room temperature. This value reflects the crystalline backbone performing as expected in a slow-loading tensile test (ASTM D638 conditions). Compressive strength is higher — typically 16,000–18,000 psi — which is relevant for valve seat and pump wear-ring designs where the primary stress mode is compressive contact load.
Elongation at break of 1.0–1.6% confirms that unfilled PPS is a brittle material in tensile loading. Design stress concentrators conservatively and specify generous corner radii in machined parts.
Flexural Modulus and Stiffness
The 600,000 psi unfilled modulus puts PPS in the same stiffness league as 33% glass-filled nylon 6/6 — but without nylon's moisture-driven dimensional shift. For applications requiring even greater stiffness (large-span structural parts, thin ribs under bending load), glass-filled PPS (33% GF) raises modulus to 1,900,000–2,000,000 psi at the cost of reduced toughness.
Creep Resistance
PPS shows low creep relative to most thermoplastics at elevated temperature. The crystalline structure resists time-dependent deformation under sustained load at service temperatures up to 400°F. For long-dwell compressive loading — valve seats held closed for extended periods, or bolted flanges under sustained clamp load — PPS's creep performance is significantly better than amorphous polymers of similar room-temperature strength.
Impact and Brittleness
The notched Izod impact value of 0.5 ft-lb/in is low. PPS cracks readily from a sharp notch and should not be used in applications that involve shock load, drop impact, or rapid mechanical impulse. Where impact resistance is required at similar service temperatures, PEEK offers substantially better toughness (notched Izod ~1.0 ft-lb/in) and PAI (Torlon) offers better still. For the full trade-off analysis, see the PPS comparisons page.
Thermal Properties
Continuous-Use Temperature
The 425°F (218°C) continuous-use rating reflects decades of field performance data in chemical pumps, downhole tools, and industrial valve bodies. It is not a short-term HDT measurement but a practical rating for sustained structural loading in service. Above 425°F, mechanical properties degrade rapidly; design to 400°F maximum for components with safety margin.
The heat deflection temperature at 264 psi (500°F / 260°C) is higher than the continuous-use rating because HDT measures a single-point deflection event, not sustained load-bearing capacity. Do not use HDT as your service temperature — use the 425°F continuous-use figure.
Thermal Expansion
The CLTE of 2.7 × 10⁻⁵ in/in·°F is low for an unfilled thermoplastic. Over a 300°F service swing, a 6-inch bore will expand approximately 0.049 inches diametrically — meaningful for tight-tolerance valve seats and pump clearances. Glass-filled grades reduce CLTE further (to ~1.5 × 10⁻⁵ in/in·°F) and are preferred when metal-to-plastic assembly clearances must be minimized across a wide temperature range.
Flame Rating
PPS achieves UL 94 V-0 without halogenated additives. The limiting oxygen index of approximately 44% means the material will not sustain combustion in air. This inherent flame resistance simplifies compliance documentation and eliminates concerns about additive migration in chemical service.
Chemical Resistance
PPS is among the most chemically inert thermoplastics available. The key qualifier is temperature: below 392°F (200°C), essentially no common industrial fluid attacks PPS measurably. Above that threshold, some strongly oxidizing acids begin to degrade the sulfide linkage.
No known solvent dissolves PPS at room temperature. This property is unique among high-performance thermoplastics and is one reason PPS is preferred for semiconductor wet-process hardware where multiple solvents contact the same component.
Resistance by Chemical Class
| Chemical Class | Resistance (≤392°F) | Notes |
|---|---|---|
| Mineral acids (HCl, H₂SO₄, HNO₃ dilute) | Excellent | Concentrated HNO₃ above 150°F — test before specifying |
| Caustic solutions (NaOH, KOH) | Excellent | Full concentration range |
| Organic solvents (acetone, MEK, toluene, TCE) | Excellent | No swelling at RT; test at elevated temp |
| Chlorinated hydrocarbons | Excellent | Excellent at RT; slight attack above 300°F |
| Fuels and oils (diesel, hydraulic) | Excellent | Preferred over nylon for fuel contact |
| Steam | Very Good | Prolonged steam above 300°F may cause slight surface degradation |
| Oxidizing acids (concentrated HNO₃, H₂SO₄ fuming) | Marginal | Avoid above 150°F at full concentration |
| Strong oxidizers (ClO₂, Cl₂ wet) | Limited | Test before specifying |
Water and Steam
The near-zero water absorption (0.02%) means that immersion in water or aqueous solutions causes no measurable dimensional change and no strength reduction. PPS can be submerged indefinitely in water, brine, or dilute acid without softening, swelling, or stress cracking — a critical distinction from nylon, which absorbs 1.5–9% moisture and undergoes measurable dimensional growth.
Steam exposure is acceptable below 300°F for extended periods. Above that threshold, prolonged steam cycling may cause minor surface discoloration and slight surface erosion over thousands of hours — not a concern for most industrial service lives.
Electrical Properties
PPS is a good electrical insulator and is used for connector housings, relay bases, and coil bobbins in applications that require both dielectric performance and thermal capability.
The dielectric constant of 3.1 and dissipation factor of 0.0004 at 1 MHz are favorable for high-frequency electrical insulation. Arc resistance of approximately 185 seconds — measured per ASTM D495 — is competitive with other high-performance engineering resins. PPS maintains these electrical properties up to its rated service temperature, unlike many polymers whose electrical performance degrades before mechanical performance does.
Density and Weight
At 1.35 g/cc, PPS is lighter than most filled engineering plastics and substantially lighter than any structural metal. A PPS pump impeller or valve body replaces metal with a material that is 50% lighter than aluminum and 83% lighter than steel — reducing inertial loads and simplifying handling during assembly.
Summary: Where PPS Properties Fit
PPS is the right choice when:
- Service temperature falls between 300°F and 425°F — above nylon or acetal, at or below the PEEK threshold
- Chemical exposure involves acids, bases, or organic solvents at elevated temperature
- Dimensional stability across moisture and temperature variation is critical
- Inherent flame retardance is required without additive complications
- Cost must be controlled relative to PEEK or Torlon
For applications demanding higher temperature, greater toughness, or biocompatibility, evaluate PEEK. For the maximum service temperature in a thermoplastic bearing, review PAI (Torlon).
Get a quote on PPS Ryton sheet and rod
Request a Quote →More related guides
Cross-cluster suggestions to help shoppers and engineers explore adjacent topics:
Applications
Industries
Compare to other materials
Frequently asked questions — Pps Ryton FAQ