Polyphenylene Oxide
Polyphenylene ether is a high-strength engineering plastic developed in the 1960s. Its chemical name is poly-2,6-dimethyl-1,4-phenylene ether, referred to as PPO (Polyphenylene Oxide) or PPE (Polypheylene ether), also known as polyphenylene oxide or polyphenylene ether.
Polyoxyxylene was made by General Electric A.S.Hay in 1956. It uses cuprous chloride as a catalyst to oxidatively couple 2,6-dimethylphenol to make polyoxyxylene. It was published in 1964 and named PPO.
Basic Properties of Polyphenylene Ether
A. It is white particles. It has good comprehensive properties and can be used in 120-degree steam. It has good electrical insulation and low water absorption, but it has a tendency to stress cracking. Modified polyphenylene ether can eliminate stress cracking.
B. It has outstanding electrical insulation and excellent water resistance, good wear resistance and electrical properties, and good dimensional stability. Its dielectric properties rank first among plastics.
C.MPPO is a modified material made by blending PPO and HIPS. All materials on the market are of this type.
D. It has high heat resistance, a glass transition temperature of 211 degrees, a melting point of 268 degrees, and a tendency to decompose when heated to 330 degrees. The higher the PPO content, the better the heat resistance, and the heat deformation temperature can reach 190 degrees.
E. It has good flame retardancy, self-extinguishing properties, and has moderate flammability when mixed with HIPS. It is light and non-toxic and can be used in the food and pharmaceutical industries. It has poor light resistance and will discolor if used in the sun for a long time.
F. It can be blended and modified with ABS, HDPE, PPS, PA, HIPS, glass fiber, etc.
PPO Plastic Raw Material Characteristics
A. PPO plastic raw material is non-toxic, transparent, and has a low relative density. It has excellent mechanical strength, stress relaxation resistance, creep resistance, heat resistance, water resistance, water vapor resistance, and dimensional stability.
B. It has good electrical properties in a wide temperature and frequency range, does not hydrolyze, has a small shrinkage rate, is flame-retardant and self-extinguishing, has poor resistance to inorganic acids, alkalis, aromatic hydrocarbons, halogenated hydrocarbons, oils, etc., and is easy to swell or stress crack.
C. It has the advantages of high rigidity, high heat resistance, flame retardancy, high strength, and excellent electrical properties. D. Polyether also has the advantages of wear resistance, non-toxicity, and pollution resistance.
D. The dielectric constant and dielectric loss of PPO plastic raw materials are one of the smallest varieties among engineering plastics, and are almost unaffected by temperature and humidity. It can be used in low, medium, and high frequency electric fields.
E. The load deformation temperature of PPO can reach above 190℃, and the brittle temperature is -170℃. G. The main disadvantage is poor melt fluidity and difficulty in processing and molding.
Physical Properties
PPO is non-toxic, transparent, and has a low relative density. It has excellent mechanical strength, stress relaxation resistance, creep resistance, heat resistance, water resistance, water vapor resistance, and dimensional stability. It has good electrical properties in a wide temperature and frequency range. Its main disadvantages are poor melt fluidity and difficulty in processing and molding. Most of the practical applications are MPPO (PPO blends or alloys). If PPO is modified with PS, it can greatly improve processing performance, stress cracking resistance and impact performance, and reduce costs, but the heat resistance and gloss are slightly reduced.
Chemical Properties
The chemical formula is abbreviated as PPO. It is a thermoplastic resin formed by oxidative coupling polymerization of 2,6-disubstituted phenol, generally in the form of khaki powder. Commonly used is polyphenylene ether synthesized from 2,6-dimethylphenol, which has excellent comprehensive properties. Its biggest feature is that it has excellent dimensional stability and outstanding electrical insulation under long-term load. It has a wide operating temperature range and can be used for a long time in the range of -127 to 121°C. It has excellent water resistance and steam resistance. The products have high tensile strength and impact strength, and good creep resistance.
Application Fields
A. Electronics and electrical
It can meet the requirements of excellent electrical insulation under humid, load and high temperature conditions. It is used to prepare TV tuners, coil cores, microwave insulation parts, shielding sleeves, high-frequency printed circuit boards, various high-voltage electronic components, TV, computer, fax machine, copier shells, etc.
B. Automobile industry
Applicable to instrument panels, window frames, shock absorbers, pump filters, etc.
C. Mechanical industry
Used as gears, bearings, pump impellers, blower impellers, etc.
D. Chemical industry
Used to make corrosion-resistant parts such as pipes, valves, filters and submersible pumps.
The performance of PPO determines its application field and scope of use:
1) MPPO has low density and is easy to process. Its heat deformation temperature is between 90 and 175℃. It has different specifications of products and good dimensional stability. It is suitable for manufacturing cabinets, chassis and precision parts of office equipment, household appliances, computers, etc.
2) The dielectric constant and dielectric loss tangent of MPPO are the lowest among the five general engineering plastics, that is, the insulation is the best, and the heat resistance is good, which is suitable for the electrical industry. It is suitable for making electrical insulation parts used in humid and loaded conditions, such as coil skeletons, tube seats, control shafts, transformer shielding sleeves, relay boxes, insulating pillars, etc.
3) MPPO has good water resistance and hot water resistance, and is suitable for making water meters and water pumps. The yarn tubes used in textile factories need to be resistant to boiling, and the yarn tubes made of MPPO have a long service life.
4) The dielectric constant and dielectric loss tangent of MPPO are not affected by temperature and frequency among engineering plastics, and it has good heat resistance and dimensional stability, which is suitable for the electronics industry.
5) Due to the development of the electronics industry and the communications industry, mobile phones, portable computers, high-performance cameras, camcorders, etc. all need lithium-ion batteries, so the lithium-ion battery market has great development prospects. The packaging materials for organic electrolytes for lithium-ion batteries used ABS or PC in the past. In 2013, foreign countries developed MPPO for batteries, and its performance is better than the former two.
6) MPPO is widely used in the automotive industry, such as instrument panels, bumpers, etc. PPO and PA alloys, especially high impact resistant specifications, are used for exterior parts and are developing rapidly.
7) In the chemical industry, modified polyphenylene ether can be used to manufacture corrosion-resistant equipment. It has particularly good hydrolysis resistance, acid and alkali resistance, and is soluble in aromatic hydrocarbons and chlorinated hydrocarbons.
8) Used in medical equipment, it can replace stainless steel and other metals in hot water storage tanks and exhaust fan mixed packing valves.
Polyphenylene Ether Recovery
The recovery methods of polyphenylene ether mainly include solvent recovery and waste recovery.
Solvent recovery method
The pretreatment method for polyphenylene ether solvent recovery includes the following steps:
Detect the water content in the polyphenylene ether solvent to be recovered.
When the water content reaches the target value, add carbonate to it, stir, stand and filter.
The filtrate is heated and distilled, and the distilled fraction enters the distillation tower for distillation separation. This method can effectively recover copper, morpholine, methanol, toluene, etc. in the mother liquor and washing liquid, avoid clogging of pipelines and distillation towers, and ensure the smooth progress of subsequent organic solvent distillation recovery process.
Waste Recovery Method
For discarded polyphenylene ether (PEEK) waste, the following two methods are mainly used for recycling and reuse:
Distillation method: extract high-purity monomers by distillation.
Extraction technology: separate the monomers and purify them.
Although these two methods can achieve high economic value and social benefits, they are complex and costly, and there are environmental pollution problems. For example, the distillation method requires a lot of energy consumption, and the extraction method produces a lot of harmful byproducts.
In order to solve these problems, a new green production process – “alcohol-free deacidification process” has been developed. This process uses high molecular polymers as carriers and specially modified phenolic compounds as raw materials. It reacts with resins under high temperature and high pressure to generate high-efficiency catalysts, which effectively improves the reaction activity and polymerization rate of the resin, reduces production costs and reduces environmental pollution.
