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Overview of Polyphenylene Sulfide PPS

 

Overview of Polyphenylene Sulfide PPS 


Polyphenylene sulfide (abbreviated as PPS), is one of the specialty engineering plastics. Together with polycarbonate (PC), polyester (PET), polyoxymethylene (POM), nylon (PA) and polyphenylene ether (PPO), PPS is one of the “world's top six engineering plastics”. And it is also one of the eight major aerospace materials. The chemical structure of PPS is as follows:
 
 

1. Structural characteristics

 

- It is a linear or slightly branched polymer composed of alternating benzene rings and sulfur atoms, and the molecular chain is highly regular. The main chain connected by the rigid benzene ring and the flexible thioether bond has the characteristics of both flexibility and flexibility, so the polyphenylene sulfide can be crystallized (the original powder has a crystallinity of up to 75 % and a melting point of up to 285 ° C);
- Since the benzene ring and the sulfur atom in the main chain form a conjugate, and the sulfur atom is not yet saturated, the thioether bond can be changed to a sulfoxide group and a sulfone group by oxidation or a benzene ring and an adjacent macromolecule form oxygen. Bridge branching or cross-linking, but does not break the main chain, so the thermal oxygen stability is outstanding, the maximum continuous use temperature can reach 260 ° C, the thermal decomposition temperature can reach 522 ° C;
- Since the polarity of the sulfur atom is bound by the benzene ring and high crystallinity, the entire polymer exhibits non-polar or weak polarity, so electrical insulation and dielectric properties, as well as chemical resistance, are also very prominent.
- Since polyphenylene sulfide has good compatibility with many polymers and additives, it can be modified by blending, strengthening, alloying and the like to improve its physical and mechanical properties.
 

2. Synthesis process

The synthesis methods of PPS mainly include solution polymerization method and condensation method.
 

Solution polymerization

Using p-dichlorobenzene and sodium sulfide as raw materials in a polar organic solvent such as hexamethylphosphoric acid triamide (HPT) or N-methylpyrrolidone (NMP) at a temperature of 175-350 ° C under normal pressure. Polyphenylene sulfide is prepared by solution polymerization, and the reaction by-product is sodium chloride. The reaction formula is:
 

Condensation

The polyphenylene sulfide is prepared by self-polycondensation at a temperature of 200-250 ° C under the protection of nitrogen with a halogenated thiophenol metal salt as a raw material, and the reaction by-product is a halogenated metal salt. The reaction formula is:
 
 

3. Modification


Polyphenylene sulfide (PPS) modified by glass fiber, carbon fiber, mineral filler, carbon nanotube, polytetrafluoroethylene, graphene, molybdenum disulfide, etc., such as conductivity, thermal conductivity, heat resistance, Material characteristics such as wear resistance, high strength, and hydrolysis resistance. This has resulted in special engineering plastics with unique functions.
 

4. Applications

PPS is widely used in automotive, electrical and electronic, machinery, petrochemical, pharmaceutical, light industry and military, aerospace and other special fields. PPS resins are also made into high-performance specialty fibers and films, making them more widely used in environmental applications and clean energy.
 
Figure PPS applied to automotive parts
 

Automotive field: headlight lamp bowl, lamp socket, sensor, vaporizer, intake pipe, petrol pump, seat spring seat, water tank, water chamber, throttle body, thermostat, regulating motor, ignition system, motor bracket, warm Tuyere bracket, thermostat bracket, housing, impeller, pump pointer ring, circulating water pump housing, brake brake bracket, transmission, brake lock, flow pump, gasoline pump, etc.
 

Figure PPS applied to automotive parts
 

Electrical appliances: electric fans, microwave oven brackets, dryers, coffee pots, toasters, rice cookers, hot air cylinders, hair irons, air conditioning scrolls, etc.
 

Figure PPS Application Electrical Field
 

Electronics: Microelectronics package, brush, brush holder, connector, connector, transformer switch, small circuit board, connector, high voltage terminal, medium wave filter, socket, lamp holder, connector, coil bobbin, fine-tuning capacitors, boiler sensor brackets, safety pedestals, electronic motor brackets, shields, micro-bearings, etc.
 

Medical devices: connectors, adapters, drug delivery equipment, surgical detectors, filtration systems, surgical tools, endoscopes.
 

Machinery: pump casing, pump wheel, tile, gear, pulley, universal head, gasket, flange, counter, level, flowmeter components, bearing cage, etc.
 

Aerospace: gun shell, helmet, warship submarine corrosion-resistant wear parts, aircraft connectors, coil bobbins, instrument panels.