Here is the English translation:
1. Heat Resistance: Aromatic rings carry the heat; thioether bonds don't fail early
The backbone contains only C–C, C–H, and C–S bonds, giving high thermal stability. TGA shows essentially no weight loss below 500°C, with a decomposition peak around 700°C.
Melting point: 280–285°C. Long-term service: 200–240°C. Short-term exposure: up to 260°C.
Note: PPS has a low glass transition temperature (~90°C) but a high melting point. Between Tg and Tm, the crystalline regions bear the load, so the material does not soften at elevated temperatures.
2. Chemical Resistance: Dense crystallization seals off permeation pathways
Below 200°C, almost no known solvent can dissolve PPS. It is stable against acids, alkalis, salts, hydrocarbons, ketones, and chlorinated hydrocarbons, with the exception of strong oxidizing acids such as concentrated nitric acid and hot concentrated sulfuric acid.
Two microstructural reasons explain this:
The backbone contains no hydrolyzable groups (no ester or amide linkages), so it does not hydrolyze and is resistant to steam.
The densely packed crystalline regions prevent small molecules from diffusing into the material; attack is limited to superficial swelling.
3. Low Water Absorption & Dimensional Stability: Non-polarity + crystallization locking
Although sulfur might be expected to be polar, partial p–π conjugation with the benzene rings, combined with high crystallinity, effectively "locks in" the polarity, giving the polymer a weakly polar character overall.
Water absorption: 0.02–0.03%. Humidity changes have essentially no effect on dimensions.
Strong π–π stacking between molecular chains provides good creep resistance, making PPS suitable for precision parts.
4. Intrinsic Flame Retardancy: Dual action of sulfur and aromatic rings
Sulfur is in the –2 oxidation state (low oxidation state). During combustion, it promotes char formation and releases species that suppress gas-phase free-radical reactions.
LOI: approximately 34–44% (varies significantly with test specimen form). PPS achieves UL94 V-0 without the addition of flame retardants.
Microscopic mechanism: condensed-phase char formation that shields oxygen, combined with gas-phase sulfur species that scavenge free radicals.
5. Electrical Insulation: Weakly polar backbone
Dielectric constant: ~3.0–3.2. Low dielectric loss, with stable performance over a wide range of temperature and frequency.
The lone pair electrons on sulfur can coordinate with metals such as Fe and Al, resulting in high adhesion strength to metals (>38 MPa).
