Polymethylpentene

Structural formula
General
Surname	Polymethylpentene
other names	Poly-4-methylpent-1-ene PMP Poly (4-methyl-1-pentene)
CAS number	25068-26-2
Monomer	4-methyl-1-pentene
Molecular formula of the repeating unit	C 6 H 12
Molar mass of the repeating unit	84.16 g mol −1
Type of polymer	Thermoplastic
properties
Physical state	firmly
density	0.83 g cm −3
Melting point	240 ° C
modulus of elasticity	820-2050 MPa
Water absorption	<0.01%
Thermal expansion coefficient	1.17 10 −4 1 / K
safety instructions
GHS labeling of hazardous substances no classification available H and P phrases H: see above P: see above
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Polymethylpentene ( abbreviated PMP ) is a partially crystalline thermoplastic and belongs to the group of polyolefins . It has a similar structure to polypropylene (PP), but the methyl groups have been replaced by isobutyl groups. The chemical resistance is comparable to PP, but there is a tendency to stress cracks due to the action of ketones or z. B. chlorinated solvents. PMP was synthesized by Giulio Natta as early as 1956 . In 1965 it was launched by ICI under the name TPX and in 1973 Mitsui Petrochemical took over production in Japan.

properties

The density of PMP is 0.83 g · cm ^-3 , the lowest of all thermoplastics. PMP is characterized by a high level of transparency (90%), which is higher in the ultraviolet range than with glass or other transparent plastics. The unusually high transparency for a partially crystalline material is based on the fact that the amorphous and crystalline areas have approximately the same refractive index. The refractive index is 1.463 and the surface tension of 24 mN / m is lower than that of some fluoropolymers. PMP has about ten times more gas permeability than polyethylene .

presentation

PMP is produced by polymerization using a Ziegler-Natta catalyst from 4-methyl-1-pentene , which was previously obtained by metal-catalytic dimerization of propene at high pressure and high temperature:

The degree of crystallization is up to 65% in tempered samples.

Resistance to chemicals

The chemical resistance of PMP to acids and alkalis is very high.

Applications

PMP is used for medical and laboratory purposes, cosmetic containers, household goods (microwave dishes) and stationery where transparency is required with high heat resistance and / or low water absorption.

processing

The processing can be done by injection molding , extrusion or blow molding . In injection molding, melt temperatures between 270 and 300 ° C and mold temperatures between 20 and 80 ° C are recommended.

Individual evidence

1. ↑ ^{a b c d e f} Properties of Standard TPX Grades at Mitsui Chemicals, accessed June 10, 2015.
2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
3. ↑ G. Natta et al., Chimia e Industria (Milano), 38, 751-65 (1956) cited in: Shunji Abe "Precision Molding of TPX" Mitsui Petrochemical Industries Ltd, Aug. 1985.
4. ↑ British Patent 984915 to Imperial Chemical Industries Limited.
5. ↑ Hans Domininghaus: The plastics and their properties, VDI-Verlag, 4th edition 1992, p 161st
6. ^ Shunji Abe "Precision Molding of TPX" Mitsui Petrochemical Industries Ltd, Aug. 1985.
7. ^ Good Fellow Material Information .