Polyphenylene Sulfide

Polyphenylene sulfide (PPS) is a new type of high-performance thermoplastic resin with the advantages of high mechanical strength, high temperature resistance, chemical resistance, flame retardancy, good thermal stability, and excellent electrical properties. It is widely used in the fields of electronics, automobiles, machinery, and chemicals.

Features

(A) General properties: PPS is a white, highly crystalline, hard and brittle polymer. The relative density of pure PPS is 1.3, but it will increase after modification. PPS has a very low water absorption rate, generally only about 0.03%. PPS has good flame retardancy, and its oxygen index is as high as 44%. Compared with other plastics, it is a highly flame retardant material among plastics (the oxygen index of pure PVA is 47%, PSF is 30%, PA66 is 29%, MPPO is 28%, and PC is 25%).

(B) Mechanical properties: The mechanical properties of pure PPS are not high, especially the impact strength is low. After being reinforced with glass fiber, the impact strength will be greatly increased from 27J/m to 76J/m, an increase of 3 times; the tensile strength will increase from 6Mpa to 137Mpa, an increase of 1 time. PPS has high rigidity. It is rare in engineering materials. The bending modulus of pure PPS can reach 3.8Gpa, and it can reach 12.6Gpa after inorganic filling modification, which is 5 times higher. However, PPO, which is famous for its rigidity, is only 2.55Gpa, and PC is only 2.1Gpa. PPS has good creep resistance under load; high hardness; high wear resistance, and its modulus at 1000 revolutions is only 0.04g, which will be further improved after filling with F4 and molybdenum disulfide; PPS also has a certain self-lubricating property. The mechanical properties of PPS are less sensitive to temperature.

(C) Thermal properties: PPS has excellent thermal properties, can withstand 260℃ in a short term, and can be used for a long time at 200~240℃; its resistance is equivalent to PI, second only to F4 plastic, which is rare among thermosetting plastics.

(D) Electrical properties: PPS has outstanding electrical properties. Compared with other engineering materials, its dielectric constant and dielectric loss angle are relatively low, and do not change much in a large frequency, temperature and temperature range; PPS has good arc resistance, comparable to thermosetting plastics. PPS is often used in electrical insulation materials, which is rare in thermosetting materials; its usage accounts for about 30%.

(E) Environmental performance: One of the biggest features of PPS is its good chemical corrosion resistance, and its chemical stability is second only to F4:
PPS is stable to most acids. Ester, copper, phenol, and fatty acids, aromatic acids, chlorinated acids, etc., but not resistant to chlorinated biphenyls and oxidizing acids, oxidants, concentrated sulfuric acid, concentrated nitric acid, aqua regia, hydrogen peroxide and sodium hypochlorite. PPS has good radiation resistance.

Application Areas

Electronics: high-voltage components, housings, sockets, terminals on televisions and computers, starting coils, blades, brush brackets and rotor insulation parts of motors, contact switches, relays, electric irons, hair dryers, lamp holders, heaters, F-class films, etc.

Automobile industry: suitable for exhaust gas recirculation valves and water pump impellers, as well as carburetors, exhaust devices, exhaust regulating valves, light reflectors, bearings, sensor components, etc.

Mechanical industry: used as bearings, pumps, valves, pistons, precision gears, as well as copiers, cameras, computer parts, catheters, sprayers, fuel injectors, instrumentation parts, etc.

Chemical industry: used to make acid-resistant and alkali-resistant valve pipes, pipe fittings, valves, gaskets and corrosion-resistant parts such as submersible pumps or impellers.

Engineering plastics: manufacturing automotive parts, anti-corrosion coatings, electrical insulation materials, etc.

Environmental protection field: PPS fiber filter material is used in high temperature and harsh working conditions in industries such as smelting, chemical industry, building materials, thermal power, garbage incinerators, coal-fired boilers, etc. It is a high-quality, high-efficiency and high-temperature resistant filter material.

Tableware field: used to make chopsticks, spoons, bowls and plates and other tableware.

PPS Recycling Technology

A. Physical recycling (mechanical method)

Applicable scenarios: clean scraps or single-component waste

Process flow: sorting-crushing-cleaning-melt granulation

B. Chemical recycling (solvent method/depolymerization method)

Solvent extraction method:

Use N-methylpyrrolidone (NMP) to dissolve PPS at 200°C, filter and precipitate (purity>95%)

Energy consumption: about 800kWh/ton

Alkaline depolymerization method:

Depolymerize in NaOH solution (concentration 10mol/L, 280°C) to sodium hydrosulfide and paradichlorobenzene

Monomer recovery rate: 80-85%

C. Energy recovery (use with caution)

High-temperature incineration (>1000°C) with tail gas treatment:

Heat energy can be recovered, but SCR denitration + wet desulfurization equipment is required.