Polymethylpentene

Polymethylpentene is a thermoplastic polymer of methylpentene monomer units.

It is better known as TPX® from Mitsui Chemicals, Inc. which is a 4-methyl-1-pentene based linear isotactic polyolefin and is made by Ziegler-Natta type catalysis. The commercially available grades are usually copolymers. It can be extruded and molded (by injection molding or blow molding).

It has a very low density (0.83g.cm-3), is transparent and colorless. Its properties are reasonably similar to those of other polyolefins although it is more brittle and more gas permeable. Therefore it is often used in films and coatings for gas permeable packaging

Given its higher melting point (~240°C) and good temperature stability, it is no surprise that polymethylpentene is used for (autoclavable) medical and laboratory applications and in microwave components or cookware.

Finally it is often used in electrical components e.g. LED molds as it is an excellent electrical insulator.