What is Polymethylpentene?
Polymethylpentene (PMP) is a thermoplastic polymer that presents a transparency equivalent to glass or acrylic. It is classified as a polyolefin and has similar properties to Polypropylene (PP), except it is slightly more susceptible to attack by oxidising agents. The most commonly used trademark name is TPX™, provided by Mitsui Chemicals, although there are others such as Zeonex and Crystalor.
PMP is more brittle and gas permeable than other materials in the polyolefin family, but on the other hand, it has good acoustical and electrical properties. PMP also has high thermal stability, excellent dielectric characteristics (meaning it is a highly insulating material or a very poor conductor of electric current) and a high chemical resistance.
PMP’s high melting point- it is normally processed at high temperatures in a range of ± 300°C – and extremely low water absorption rate, makes PMP an excellent choice for items that require steam sterilization. Since PMP does not absorb water or moisture, it is not necessary to dry PMP before processing provided that it has been stored under normal conditions.
Because it is one of the lightest materials among thermoplastic polymers, it is suited for commercial use and can be used for a wide range of purposes. PMP is available in pellet form and can be injection moulded, blow moulded, or extruded into film, rods or sheets. Unlike PC, PMMA and other amorphous resins, PMP is crystalline and therefore shows bigger mould shrinkage. The surface finish of a mould determines the transparency of a PMP product as PMP easily captures the roughness of a mould due to its high flow ability. The most suitable method to colour PMP is dry blending with colour masterbatch. When choosing the colour masterbatch, it should have high heat resistance which can be sustained at the processing temperature.
Because of its excellent heat-resistance, release property and chemical resistance, PMP is used for industrial materials, including mandrels and sheaths in the manufacture of high-pressure rubber hose, mould cups for LED and other applications as well as release paper in the manufacture of synthetic leather.
Polymethylpentene chemical resistance
PMP has a similar chemical resistance to polypropylene but has higher temperature capabilities. Its transparency, rigidity and resistance to chemicals is what make PMP a superior material for labware, and medical and laboratory equipment. PMP has better chemical resistance than polycarbonate and acrylic resin and shows excellent chemical resistance particularly against acids, alkalis and alcohol. This is why it is used in various applications which require chemical resistance, such as cosmetics container caps and tubes, experimental apparatus and analytical cells.
PMP is often used for packaging that requires gas permeability in the shape of films and coatings. Other applications include microwave components, and cookware. Normally produced in 3 mm and 5 mm thickness the material can have a gloss or matte finish. As a film it has a high-performance heat resistance and can be used for a wide range of applications including flex circuits. The non-stickiness polymethylpentene film, can also be stretched up to 300% to allow easier contouring along edges and corners. PMP is available in clear and tinted versions and as a single layer or multilayer.
PMP applications include:
- Cosmetic Caps and Tubes
- Heat Resistant Non-Woven Materials
- LED Molds
- Medical Devices
- Release Film
- Release Paper for Synthetic Leather