Ryton® PPS - Health, Safety & Environment

Safe Handling

Polyphenylene sulfide (PPS) resin is essentially nontoxic by ingestion. In acute skin and eye irritancy evaluations, PPS produces only the minimal degree of irritation which can be perceived. It appears that PPS dust is inert and presents no hazard to health from long-term inhalation exposure. It should be treated as a typical "nuisance-type" dust.

Off-gases produced during melt processing of PPS can be irritants to mucous membranes, therefore adequate ventilation of the processing area is recommended when melt processing PPS compounds.

For information on Ryton® PPS compliance with environmental and restricted substance regulations, refer to the Ryton® PPS Regulatory Information. For Underwriters Laboratory (UL) Certifications, visit our UL Database.

For further information and to receive Safety Data Sheets (SDS), contact our technical specialists.

Fire Safety

Fire Safety Standards

AIRBUS ATS 1000-001

  • Ryton® R-4 PPS

NF F 16-101 (fire proof)
NF T 51-071
NF C 20-455

  • Ryton® R-4-200NA PPS Class I3
  • Ryton® R-4 PPS Class I2

NF F 16-101/102 (smoke index)

  • Ryton® R-4-200NA PPS Class F3
  • Ryton® R-4 PPS Class F4

NF X 10-702/70-100 (fumes and toxicity)

  • Ryton® R-4 PPS Class F3

Flammability & Smoke Generation

Burning Characteristics of Polyphenylene Sulfide

Although it can be ignited, polyphenylene sulfide (PPS) will neither sustain prolonged combustion nor support significant flame propagation when tested by any of the standard tests commonly used for plastics. Unfortunately, no lab test can be expected to encompass all of the variables of an uncontrolled fire, such as a building or equipment fire, even if one fire scenario could be selected as "typical." 

In various tests using heat, flame and electrical ignition sources, PPS will burn if the ignition source is hot enough, and will continue to burn until the ignition source is removed. As PPS burns, it chars and may bubble somewhat, which can reduce heat transfer to the remaining material. In general, PPS compounds do not drip as they burn, but thin sections of the higher flow compounds can soften or melt enough to deform during combustion and may drip if the ignition source is hot enough. The "flame-retardance" of Ryton® PPS compounds is inherent to the stable chemistry of the PPS polymer itself, and does not rely on flame-retardant additives which can compromise the electrical and mechanical performance of compounds.

Normal combustion of PPS will generate carbon dioxide, water vapor, sulfur oxides and may produce carbon monoxide, carbonyl sulfide and various hydrocarbons and hydrocarbon oxidation products (such as ketones, aldehydes and organic acids) depending on temperature and air availability. Incomplete combustion can also produce formaldehyde. Trace amounts of hydrogen chloride and nitrogen oxide gases may also be generated.

Although lab tests cannot predict burning behavior in a real fire, they are presented here for comparison with other materials. Test results for representative 40% glass fiber reinforced PPS (Ryton® R-4 PPS) and 65% glass/mineral filled PPS (Ryton® R-10 7006A PPS) compounds are provided. See our Product Data Sheets and information on Fire Safety Standards and UL Yellow Card Listings for performance of Ryton® PPS compounds in additional tests.

Ignition Temperature - ASTM E 659

This test was performed by Underwriters Laboratories. It consists of placing some plastic chips or shavings into a glass flask that is submerged in a bath of molten alloy. The ignition chamber is purged and air added to assist ignition of the sample. If the test sample does not flame or glow, the flask is purged of residual gases, vapors and tested material. The temperature is raised and new sample added to the flask. This procedure is repeated until a minimum temperature is reached that induces the test material to glow or burn. That minimum combustion temperature is reported as the ignition temperature.

40% Glass Fiber Reinforced PPS: 540°C (1004°F)

Flash Point - ASTM D 1929

The flash point was determined by conventional procedures as described in ASTM D 1929 or ISO 871.

40% Glass Fiber Reinforced PPS: >500°C (>932°F)

Radiant Panel Burn Test - ASTM E 162

The radiant panel burn test measures the surface flammability of materials when exposed to a radiant heat source. A 6 inch by 18 inch (15.2 cm by 45.7 cm) specimen is mounted with its long dimension inclined 30° off the vertical. The specimen is parallel to, but 4.75 inches (12 cm) away from, a radiant panel heat source maintained at 1238 ± 72°F (670 ± 22°C). A pilot burner ignites the top of the specimen, and the heat evolved by the specimen and its rate of burning are used to calculate a flame spread index, useful for comparing various materials.

40% Glass Fiber Reinforced PPS

65% Glass/Mineral Filled PPS

Average Thickness

0.134 in (3.4 mm)

0.134 in (3.4 mm)

Flame Spread Index

2 inches (5.1 mm)

2 inches (5.1 mm)

Visual Characteristics

charring, slight melting, light smoke

charring, light smoke

Smoke Density - ASTM E 662

This smoke test developed by the National Bureau of Standards employs a completely closed cabinet, measuring 36 inches by 36 inches by 24 inches (91 cm x 91 cm x 61 cm). A three inch (76 mm) square specimen is supported in a frame such that a surface area of 2.56 in² (16.5 cm²) is exposed to heat under either flaming or non-flaming (smoldering) conditions. The heat source is a circular foil radiometer adjusted to give a heat flux of 2.5 W/cm² at the specimen surface.

The smoke density is measured photometrically in terms of light absorption. The photometer path is vertical to minimize measurement differences due to smoke stratification which could occur with a horizontal photometer path at some fixed height. The full 36 inch (91 cm) height of the chamber is used to provide an overall average for the entire chamber. Smoke measurements are expressed in terms of specific optical density, which represents the optical density measured over unit path length within a chamber of unit volume, produced from a specimen of unit surface area. Since this value is dimensionless, it provides the advantage of presenting the smoke density measurement independent of chamber volume, specimen size or photometer path length, provided a consistent dimensional system is used.

The time to reach a critical smoke density, also called obscuration time, is a measure of the time available before a "typical" occupant in a "typical" room would find vision so obscured by smoke as to hinder escape. The value of specific optical density describing this critical level is 16, based on 16% light transmittance under certain specific conditions of room dimensions.


in mm

Maximum Specific
Optical Density

Time, min





40% Glass Fiber Reinforced PPS

0.060 (1.5)





40% Glass Fiber Reinforced PPS

0.125 (3.2)





40% Glass Fiber Reinforced PPS

0.170 (4.3)





65% Glass/Mineral Filled PPS

0.170 (3.2)





Red Oak (for reference)

0.250 (6.3)





Ryton® PPS Compound

Thickness in mm

Specific Optical Density, Flaming

1.5 min

4.0 min



0.125 (3.2)





0.125 (3.2)





0.125 (3.2)




Flammability of Interior Materials - FMVSS 302

This U.S. Federal Motor Vehicle Safety Standard (FMVSS) specifies burn resistance requirements for materials used in the occupant compartments of motor vehicles. A test specimen 14 inches (35.6 cm) long by 4.0 inches (10.2 cm) wide and up to 0.5 inches (1.3 cm) in thickness is mounted between two U-shaped steel brackets exposing an area 11 inches (27.9 cm) long by 2.0 inches (5.1 cm) wide, with an exposed edge at one end. 

The mounted specimen is placed horizontally and flatwise in a burning chamber, the exposed edge is ignited using a gas burner, and timing is started when the flame front progresses to a point 1.5 inches (3.8 cm) from the ignited edge of the specimen. A burn rate is determined by the time required for the flame front to progress to a point 9.5 inches (24.1 cm) from the ignited edge of the specimen, or the distance the flame front progresses within five minutes, or the time required and the distance the flame front progresses before the specimen self-extinguishes, whichever occurs first. The standard requires that the burn rate be no more than 4.0 inches/minute (10.2 cm/minute).

When Ryton® PPS compounds are tested according to this standard at thicknesses of 0.063 inches (1.6 mm) or thicker, the specimens will typically self-extinguish within five seconds, and before the flame front even progresses to a point 1.5 inches (3.8 cm) from the ignited edge of the specimen. Thus, Ryton® PPS compounds will self-extinguish before the timing to determine the burn rate is even initiated according to the test procedure.

Steiner Tunnel Test - ASTM E 84

The Steiner Tunnel test is intended to compare the flame spread and smoke generation behavior of various building materials when burning within a rectangular duct with air flowing through it. A specimen 24 ± 1.5 feet (7.3 ± 0.46 m) long by 22 ± 2 inches (56 ± 5 cm) wide and up to 4 inches (10 cm) thick is positioned along the top of a chamber measuring 25 ± 0.25 feet (7.62 ± 0.076 m) long by 17.75 ± 0.25 inches (45.1 ± 0.6 cm) wide by 12.0 ± 0.5 inches (30.5 ± 1.3 cm) in height. 

One end of the specimen is ignited by a gas burner in the presence of a controlled air flow through the chamber towards the opposite end of the specimen. The rate of progression of the flame front along the specimen is measured, and the smoke density is measured photometrically in a vent pipe at the exhaust end of the chamber. The recorded measurements are compared with the behavior of cement board and red oak wood to calculate a Flame Spread Index (FSI) and a Smoke Developed Index (SDI).

In this test, unfilled PPS gave an FSI of 5 and an SDI of 155, giving it “Classification A” according to the 2003 International Building Code® (Chapter 8 Interior Finishes, Section 803 Wall and Ceiling Finishes) and NFPA 5000 (Chapter 10 Interior Finish, Section 10.3 Interior Wall or Ceiling Finish Testing and Classification).


Ryton® PPS compounds are inherently flame resistant. All Ryton® PPS compounds have UL 94 V-0 and many have UL 94 5VA non-flammability ratings without using flame retardant additives. The limiting oxygen index, another good method of comparing the flammability of various materials, is the minimum percentage of oxygen in a test atmosphere that allows the plastic to support continued combustion. The limiting oxygen index of Ryton® PPS compounds is about 50%, making them among the most flame resistant plastics.

When comparing flammability ratings of engineering plastics, it is important to note that many require flame retardant additives to be classified UL 94 V-0. Flame retardant additives tend to be detrimental to the mechanical and electrical properties of a plastic. Most common flame retardant additives break down after a single pass through an injection molding machine, so parts molded using regrind will not be as flame retardant as parts molded from virgin material. Furthermore, the thermal degradation of flame retardant additives can produce toxic, corrosive off gasses. Since Ryton® PPS compounds require no flame retardant additives, regrind is as flame resistant as virgin material and the other undesirable effects of using flame retardant additives are also avoided.



Off-Gassing of PPS Compounds

Off-Gases from Ryton® PPS Compounds and Ryton® PPS Alloy Compounds

Parts molded from Ryton® PPS compounds typically exhibit no detectable off-gassing at temperatures below 50°C (122°F). Parts molded from Ryton® PPS Alloy compounds may have a mild odor.

The off-gasses from Ryton® PPS compounds and Ryton® PPS Alloy compounds at elevated temperatures typically consist of mostly water vapor and small amounts of carbon oxides and sulfides (such as carbon dioxide, carbon disulfide, carbon monoxide and carbonyl sulfide) and sulfur dioxide. The off-gasses will also include trace amounts of various low molecular weight (one to five carbon) aliphatic hydrocarbons and hydrocarbon oxidation products such as aldehydes, ketones, and carboxylic acids, as well as trace amounts of low molecular weight aromatic hydrocarbons, including some chlorine-containing and sulfur-containing aromatic hydrocarbon substances. The mixture of trace substances in the off-gasses is highly variable and dependent upon the temperature. Some of the off-gasses may be irritants to the eyes and respiratory tracts, therefore adequate ventilation of the processing area is recommended when melt processing Ryton® PPS compounds and Ryton® PPS Alloy compounds.

NASA Outgassing Test

Ryton® PPS compounds have successfully passed the NASA Outgassing Test, carried out in accordance with ASTM E 595. The test is conducted at 125°C (257°F) under a vacuum of less than 5 x 10-5 mm Hg over a period of 24 hours. The two values reported are the percent Total Mass Loss (% TML), which is the percent of total weight loss of material that volatilizes from the sample, and the percent Collected Volatile Condensable Material (% CVCM), which is the weight percent of material that volatilizes from the sample and then condenses at 25°C (77°F). The NASA outgassing requirement is a maximum of 1.0% TML and a maximum of 0.1% CVCM. All Ryton® PPS compounds tested have easily met the NASA specifications.

Ryton® PPS Compound















Drinking Water and Food Contact Standards

Potable Water, Food Contact and Medical Standards

Certain Ryton® PPS compounds and Ryton® PPS Alloy compounds can meet the requirements of various industry standards and regulations regarding use in applications requiring contact with potable water and food, as well as potential use for medical devices not requiring implantation. A summary is provided below. Please contact your nearest technical service center for further information.

Drinking Water

NSF Standard 61

  • R-4
  • R-4-02-XT
  • R-4-242-NA
  • R-4-242-BL
  • XE-5501-BL

BS6920 / WRAS 

  • R-4-242-NA
  • R-4-242-BL
  • XE-5030-BL
  • XE-5501-BL


  • R-4-242-NA
  • R-4-242-BL
  • XE-5501-BL


  • R-4-242-NA
  • R-4-242-BL
  • XE-5501-BL


  • R-4-242-NA
  • R-4-242-BL
  • XE-5501-BL

Food Contact

U.S. FDA and EU EC No. 10/2011

  • Includes EC No. 1935/2004, VGP/VC 3048441 and BfR/LFGB
  • R-4-232NA
  • Food Contact Status Letter for R-4-232NA
  • Includes EC No. 1935/2004, VGP/VC 3048441 and BfR/LFGB
  • Product Regulatory Overview for R-4-232NA
  • V-1, P Series, PR Series, QA Series and QC Series PPS Polymers
  • Food Contact Status Letter for PPS Polymers

U.S. FDA FCN 1083

  • V-1, P Series, PR Series, QA Series and QC Series PPS Polymers
    For use with all types of food under Conditions of Use A through H and J.
  • FCN 1083 Letter

21 CFR 177.2490 (Coatings)

  • V-1 and PR11 Powders
  • 21 CFR 177.2490 Listing for PPS

Underwriters Laboratory

Underwriters Laboratory (UL)

Underwriters Laboratory (UL) Yellow Card certificates are available on our UL Database.