Polymethylpentene

Polymethylpentene, abbreviated PMP and commonly sold under the trade name TPX, is an amorphous thermoplastic polymer in the polyolefin family. It is produced by polymerizing the methylpentene monomer and is valued for its combination of optical clarity, chemical resistance, and heat resistance.

PMP is transparent and maintains high optical clarity over a wide temperature range. It exhibits low moisture absorption and excellent resistance to many solvents, acids, and bases. The material has a relatively high glass-transition temperature for a transparent polymer, enabling continuous use at elevated temperatures (roughly 150–180°C, depending on grade). It is also lightweight with a low density.

Processing and grades: PMP is melt-processed by conventional thermoplastic methods, including extrusion, injection molding, blow molding, and forming of thin films. Grades exist with different melt viscosities and additives to tailor clarity, toughness, and chemical resistance.

Applications: PMP is used in laboratory ware and chemical equipment, piping and fittings, and reaction vessels that require clarity and chemical inertness. It is also employed in medical devices, light-guiding components, and certain cookware liners in markets that value its purity and heat performance.

Limitations: While chemically resistant and thermally stable, PMP can be more expensive than more common polyolefins and may exhibit limited impact resistance at low temperatures. Some grades may require stabilization for UV exposure, and its processing can be less forgiving than more widely used plastics in some applications.