Polymethylpentene (PMP), also known as poly(4-methyl-1-pentene), is a

thermoplastic A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...

polyolefin A polyolefin is a type of polymer with the general formula (CH2CHR)n where R is an alkyl group. They are usually derived from a small set of simple olefins (alkenes). Dominant in a commercial sense are polyethylene and polypropylene. More speciali ...

. It is used for gas-permeable packaging, autoclavable medical and laboratory equipment,

microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ran ...

components, and

cookware Cookware and bakeware is food preparation equipment, such as cooking pots, pans, baking sheets etc. used in kitchens. Cookware is used on a stove or range cooktop, while bakeware is used in an oven. Some utensils are considered both cookware ...

. It is commonly called TPX, which is a trademark of

Mitsui Chemicals is a Japanese chemicals company listed on the Nikkei with business interests in Japan, Europe, China, Southeast Asia and the USA. It is one of the leading chemical companies in Japan and is part of the Mitsui conglomerate. The company mainly ...

Production

Polymethylpentene is a 4-methyl-1-pentene-derived linear

isotactic Tacticity (from el, τακτικός, taktikos, "relating to arrangement or order") is the relative stereochemistry of adjacent chiral centers within a macromolecule. The practical significance of tacticity rests on the effects on the physical p ...

and is made by Ziegler–Natta type

catalysis Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

. The commercially available grades are usually

copolymers In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are some ...

. It can be

extruded Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex c ...

and moulded (by

injection moulding Injection moulding (U.S. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals (for ...

blow moulding Blow molding (or moulding) is a manufacturing process for forming hollow plastic parts. It is also used for forming glass bottles or other hollow shapes. In general, there are three main types of blow molding: extrusion blow molding, injection ...

Physical properties

Polymethylpentene melts at ≈ 235 °C. It has a relatively low

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

(0.84 g/cm³) among plastics and is

transparent Transparency, transparence or transparent most often refer to: * Transparency (optics), the physical property of allowing the transmission of light through a material They may also refer to: Literal uses * Transparency (photography), a still, ...

. It has low moisture absorption, and exceptional acoustical and electrical properties. Its properties are reasonably similar to those of other

s, although it is more

brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Bre ...

and more gas permeable. The polymer also has a high

thermal stability In thermodynamics, thermal stability describes the stability of a water body and its resistance to mixing.Schmidt, W. 1928. Über Temperatur und Stabilitätsverhältnisse von Seen. Geogr. Ann 10: 145 - 177. It is the amount of work needed to tr ...

, excellent

dielectric In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the mate ...

characteristics and a high

chemical resistance The chemical resistance of a material or surface can be determined in compliance with ISO 2812 Paints and varnishes – Determination of resistance to liquids – Part 1: Immersion in liquids other than water (ISO 2812-1:2007); German Version EN I ...

. The

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

line phase has a lower

than the

amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal. Etymology The term comes from the Greek ''a'' ("wi ...

phase. In comparison to other materials being used for operating in THz range, TPX shows excellent optical properties with a wavelength independent

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

of 1.460±0.005 between

visible light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 te ...

and 100~GHz.

Applications

*Applications include

sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect o ...

covers, speaker cones,

ultrasonic Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies fr ...

transducer heads, and lightweight structural parts. It is also FDA compliant for use in

food processing Food processing is the transformation of agricultural products into food, or of one form of food into other forms. Food processing includes many forms of processing foods, from grinding grain to make raw flour to home cooking to complex industr ...

machinery. Polymethylpentene is often used in films and coatings for gas-permeable packaging. *Because of its high

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...

and good temperature stability, polymethylpentene is used for autoclavable medical and laboratory equipment, microwave components, and

. *It is also often used in electrical components e.g.

LED A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...

molds because it is an excellent

electrical insulator An electrical insulator is a material in which electric current does not flow freely. The atoms of the insulator have tightly bound electrons which cannot readily move. Other materials—semiconductors and conductors—conduct electric current ...

. *TPX is a hard, solid material, which can be mechanically shaped into various optical components like

lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...

es and

window A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent materia ...

s. It is used in CO₂ laser pumped molecular lasers as an output window because it is transparent in the whole terahertz range and totally suppresses the ~10 μm pump radiation.

References

* Krentsel B.A., Kissin Y.V., Kleiner V.I., Stotskaya S.S. ''Polymers and Copolymers of Higher a-Olefins'', Hanser Publishers: New York, 1997. * H. C. Raine, ''J. Appl. Polym. Sci.'' 11, 39 (1969). * Mitsui Chemicals Co., ''Properties of Standard TPX Grades'', 2004. * FDA CFR Title 21 Sec. 177.1520 Olefin polymers (C) 3.3b for TPX(4-methylpentene-1-based olefin copolymer)

External links

Mitsui Chemicals, Inc.Tydex J.S.Co. - Manufacturer of polished TPX lenses and windows
{{Plastics Plastics Polyolefins Packaging materials Household chemicals Dielectrics Thermoplastics Organic polymers