Polymethylpentene

• Poly -4- methylpent -1-ene
• PMP
• Poly (4-methyl -1-pentene )

Thermoplastic

Fixed

0.83 g · cm -3

240 ° C

Partially crystalline

820-2050 MPa

<0.01%

1.17 10-4 1 / K

Polymethylpentene (abbreviation PMP) is a partially crystalline thermoplastic and belongs to the group of polyolefins. It is similar to polypropylene (PP) constituted, but the methyl groups are replaced with isobutyl groups. The chemical resistance is comparable to PP, but tends to suffer from tension cracks when exposed to ketones or chlorinated solvents. PMP was synthesized in 1956 by Giulio Natta. In 1965 it was brought by ICI under the name TPX on the market and in 1973 took over Mitsui Petrochemical 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 transparency (90%), which is higher than that of glass or transparent plastics in the ultraviolet region. For a semi-crystalline material is based on the unusually high degree of transparency that the amorphous and crystalline regions have approximately the same refractive index. The refractive index is 1.463, and the surface tension is 24 mN / m is less than some of the fluoropolymer. PMP has a ten times higher gas permeability than polyethylene.

Representation

PMP is represented by polymerization using Ziegler-Natta catalyst consisting of 4-methyl -1-pentene, which has previously been obtained by metal catalyzed dimerization of propene at high pressure and high temperature:

The degree of crystallization of up to 65% in the annealed samples.

Resistance to chemicals

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

Applications

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

Processing

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