Noryl
Encyclopedia
Noryl is a blend of polyphenylene oxide (PPO) and polystyrene
(PS) that was developed by General Electric
Plastics in 1966 (now owned by SABIC
). It is a rare example of a homogeneous mixture of two polymers. Most polymers are incompatible with one another, so tend to produce separate phases when mixed. The compatibility of the two polymers in Noryl is caused by the presence of a benzene ring in the repeat unit
s of both chains.
s. Injection molding must ensure that moldings are stress-free.
Like most other amorphous thermoplastics, Noryl is sensitive to environmental stress cracking
when in contact with many organic liquids. Compounds such as gasoline
, kerosine and methylene chloride may initiate brittle cracks which lead to product failure.
Noryl has possible applications in the production of hydrogen
, where it could serve as cost-effective electrode
s in an electrolyzer, replacing expensive rare elements. It is highly resistant against the alkaline potassium hydroxide. For conductivity the plastic is sprayed with a nickel-based catalyst.
Noryl is being investigated as a possible replacement for polycarbonate used in the manufacturing of Blu-ray Discs.
It is also used in certain construction products.
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
(PS) that was developed by General Electric
General Electric
General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
Plastics in 1966 (now owned by SABIC
SABIC
SABIC is a diversified manufacturing company, active in chemicals and intermediates, industrial polymers, fertilizers and metals. It is the largest public company in Saudi Arabia as listed in Tadawul, but the Saudi government still owns 70% of its shares...
). It is a rare example of a homogeneous mixture of two polymers. Most polymers are incompatible with one another, so tend to produce separate phases when mixed. The compatibility of the two polymers in Noryl is caused by the presence of a benzene ring in the repeat unit
Repeat unit
An essential concept which defines polymer structure, the repeat unit or repeating unit is a part of a polymer chain whose repetition would produce the complete polymer by linking the repeat units together successively along the chain, like the beads of a necklace.A repeat unit is sometimes called...
s of both chains.
Properties
The addition of polystyrene to PPO increases the glass transition temperature above 100 °C, owing to the high Tg of PPO, so Noryl is stable in boiling water. The precise value of the transition depends on the exact composition of the grade being used. There is a smooth linear relation between weight content of polystyrene and the Tg of the blend. Noryl has good electrical resistance, so is widely used for switch boxes. However, product design is important in maximising the strength of the product, especially in eliminating sharp corners and other stress concentrationStress concentration
A stress concentration is a location in an object where stress is concentrated. An object is strongest when force is evenly distributed over its area, so a reduction in area, e.g. caused by a crack, results in a localized increase in stress...
s. Injection molding must ensure that moldings are stress-free.
Like most other amorphous thermoplastics, Noryl is sensitive to environmental stress cracking
Environmental stress cracking
Environmental Stress Cracking is one of the most common causes of unexpected brittle failure of thermoplastic polymers known at present. Environmental stress cracking may account for around 15-30% of all plastic component failures in service.ESC and polymer resistance to ESC have been studied...
when in contact with many organic liquids. Compounds such as gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...
, kerosine and methylene chloride may initiate brittle cracks which lead to product failure.
Applications
Noryl has numerous applications in electronics, electrical equipment, coating, machinery, etc.Noryl has possible applications in the production of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
, where it could serve as cost-effective electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
s in an electrolyzer, replacing expensive rare elements. It is highly resistant against the alkaline potassium hydroxide. For conductivity the plastic is sprayed with a nickel-based catalyst.
Noryl is being investigated as a possible replacement for polycarbonate used in the manufacturing of Blu-ray Discs.
It is also used in certain construction products.
External links
- MIT Technology Review - Hydrogen on the Cheap
- SABIC Innovative Plastics overview of Noryl