Polyphenylene ether
Polyphenylene ether (PPE) resin is a macromolecule made mainly from 2,6-xylenol as monomer, and this amorphous resin is characterized by high thermal resistance because of the glass-transition temperature (Tg) exceeds 200℃ as pure PPE itself.
PPE is featured with low specific gravity, low moisture absorption, high dielectric strength, good creep resistance, and weather durability. It has the following macromolecular structure:
In the market, we can see the material titled with PPE, while sometimes with PPO. Actually, they refer to the same material, but need to be aware that PPO is a registered trademark of SABIC Innovative Plastics.
However, since the molten flowability of the pure PPE itself is extremely poor, this resin is widely used as polymer alloy materials.
1. Polyphenylene oxide is completely miscible with polystyrene in all proportions. The glass transition temperature of these blends changes smoothly with composition.
These blends with 25-60% (weight) of PPE, designed for injection or blow moulding, extrusion calendering, thermoforming and reinforced with 0-30 weight percentage glass fiber.
2. Unlike PPE/PS as miscible pairs, PPE and PA are incompatible polymer pairs. Usually, a compatibilizer precursor that is miscible with Polyphenylene ether phase and that react with the polyamide phase is used to compatibilize the system. These are blends (compatibilized PPE/PA) with 40-60 weight percentage of nylon.
PPE provides excellent heat resistance, toughness and nylon (crystalline) resists oils, gasoline and solvent, PPE/PA alloys have a lower density, higher toughness. PPE/PA grades are used in fluid handling applications which require chemical resistance, dimensional stability and heat resistance.
PPE alloys have a variety of applications.
- Automotive
- Instrument panels, steering column, cladding, central consoles, loudspeaker housings, radiator tanks, cable connectors, bulb sockets, air inlet and outlet grills and outer mirror housings.
- Electronics
- Microwave insulation component, transformer housings. Computer terminals, printers, modems, typewriter bases, video games, copier, capacitor casings, outlet boxes, coil bobbins, smoke detectors, intrusion alarm, motor covers and switches.
- Miscellaneous
- Water pumps, water meters, sprinkler systems, hot water tank, washing machine parts, welder’s protective visors, tennis racquets, textile components and valves for drink vending machines.
PPE is not affected by acids, bases and detergents; but in solvent like mineral oil, ketones and esters, it can crack due to stress. And Organic solvents such as aliphatic hydrocarbons, halogenated aliphatic hydrocarbons and aromatic hydrocarbons will make them swell and dissolve.Thus, we can use chemical solvents to detect stress cracking point of the article. In this scenario, tributyl phosphate is usually the solvent for PPE made articles with an immersion time 20-30s.
One thing worth mention here is that some manufacturers apply this method, which is set no crack after immersion in TBP solvent, to determine whether the product is qualified or not. This is self-contradiction. To find the stress concentration point is one thing and the plastic material’ chemical property is another thing.