PPS Ryton: Polyphenylene Sulfide High-Temp Chemical-Resistant Polymer
Published: 2026-05-25
Polyphenylene sulfide (PPS), best known by Solvay's trade name Ryton, is a semicrystalline high-performance thermoplastic with exceptional inherent flame retardancy (UL94 V-0, the highest rating, without flame-retardant additives), outstanding...
Polyphenylene sulfide (PPS), best known by Solvay's trade name Ryton, is a semicrystalline high-performance thermoplastic with exceptional inherent flame retardancy (UL94 V-0, the highest rating, without flame-retardant additives), outstanding chemical resistance (virtually inert to all solvents below 200°C), and the best flowability of any high-temperature polymer—enabling thin-wall molding of complex geometries with tight tolerances. PPS is the material of choice for automotive under-hood components (fuel system connectors, coolant pump impellers, EGR valve components) and electrical/electronic encapsulation where its combination of high HDT, dimensional stability, and dielectric properties is unmatched at its price point.
The tradeoff for PPS's outstanding chemical resistance is brittleness in the unfilled state (notched Izod impact ~25 J/m versus ~85 J/m for unfilled PEEK). Glass fiber reinforcement (40% GF) is standard for structural applications, raising tensile strength to 160 MPa and impact resistance to 80 J/m. Glass-mineral hybrid grades (65% GF/mineral) provide the best dimensional stability for electrical connectors requiring tight pin retention over thermal cycling. PPS requires mold temperatures of 135-160°C to achieve full crystallinity—oil-heated molds are standard for PPS processing.
Technical Properties
| Density | 1.35 g/cm³ |
|---|---|
| Tensile Strength | 90 MPa (unfilled); 160 MPa (40% GF) |
| Melting Point | 285 °C |
| Shrinkage Rate | 0.3-0.5% (40% GF) |
| Flexural Modulus | 3.8 GPa (unfilled); 14 GPa (40% GF) |
| Hdt | 265 °C at 1.82 MPa (40% GF) |
| Continuous Service Temp | 220 °C |
Engineering Tool: Shrinkage & Cost Estimator
Calculate part weight, mold cavity dimensions accounting for shrinkage, and material cost — all locally in your browser.
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| Solvay Ryton | |
| Torelina | |
| Fortron PPS | |
| DIC PPS |
Frequently Asked Questions
What makes PPS inherently flame retardant without additives?
PPS's polymer backbone consists of alternating sulfur and para-phenylene groups. When exposed to flame, the sulfur atoms oxidize to form a stable char layer (polyphenylene sulfone/sulfonate) that acts as a thermal insulation barrier, while the para-phenylene rings provide a high char yield (approximately 50% of the original polymer mass). This char formation mechanism is inherent to the polymer chemistry—it does not require halogen or phosphorus flame retardant additives that can leach out over time. The limiting oxygen index (LOI) of unfilled PPS is 44 (atmosphere is 21% O₂), meaning PPS will not sustain combustion in air without an external heat source.
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References & Industry Standards
- ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
- UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
- MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
- ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org