Polyaramid Polymetaphenylene Isopthalamide ( Nomex ) - Properties and Applications - Supplier Data by Goodfellow

Background

Polyaramid Polymetaphenylene Isopthalamide or Nomex ® is an infusible, wholly aromatic polymer that can strictly be described as nylon I,I - but rarely is. Manufactured only as a fibre (by solution spinning), it has a very high thermal stability and temperature and flame resistance. In contrast to its chemical isomer Kevlar®, the tensile properties of Polyaramid Polymetaphenylene Isopthalamide or Nomex ®  are similar to those of normal textile fibres but its hydrolysis resistance in hot wet conditions is better (than Kevlar’s). Its radiation resistance is also very good.

Forms

The Polyaramid Polymetaphenylene Isopthalamide or Nomex ® fibre is converted into a number of fibre-based forms, including : calendered and uncalendered papers, pressboards of three different densities and honeycomb. The last is made from Nomex® paper coated in a phenolic resin. Other forms include felts.

Applications

Applications of Polyaramid Polymetaphenylene Isopthalamide or Nomex ® include protective clothing (e.g. for firefighters and racing drivers), process equipment and insulation and filtration media.

Polyaramid is quite extensively used in composites, which are lighter than those based on carbon fiber and electrical insulation.

Its mechanical properties are mostly inferior; more precisely it has a high specific tensile strength close to that of carbon fiber composites, but relatively low strength in compression.

Nomax is used in protective clothing e.g. firefighters uniform Image Credit: ShutterStock: mat277

Nomax is used in protective clothing e.g. firefighters uniform Image Credit: ShutterStock: mat277

Explanation of Type Numbers

. .
T410 Calendered Paper
T411 Un-calendered Paper
T418 Calendered Paper, containing 50% mica
T992 Low Density Pressboard
T993 Medium Density Pressboard
T994 High Density Pressboard

Key Properties

The key properties of Polyaramid Polymetaphenylene Isopthalamide or Nomex ® are tabulated below.

Table 1. Key properties

Chemical Resistance
Acids - concentrated Fair
Acids - dilute Good
Alcohols Good
Alkalis Fair - Good
Aromatic hydrocarbons Good
Greases and Oils Good
Ketones Good
Physical Properties
Density ( g.cm-3 ) 1.38
Limiting oxygen index ( % ) 29
Radiation resistance - Alpha Good
Water absorption - equilibrium ( % ) 9
Thermal Properties
Coefficient of thermal expansion ( x10-6 K-1 ) 20
Specific heat ( J.K-1.kg-1 ) 1200
Thermal conductivity ( W m-1 K-1 ) 0.13 @ 23
Upper working temperature ( °C ) 200 - 300
Properties Polyaramid Film
Property Value
Material T410 T411 T418
Density g.cm-3 0.72-1.05 0.3 1.1
Dielectric Constant @ 60 Hz 1.6 - 3.4 1.2 2.5
Dielectric Strength @ 130 µm thick KV.mm-1 17-55 9-18 33-63
Dissipation Factor @ 60 Hz 0.004-0.007 0.003 0.003
Elmendorf Tear Strength N.mm-1 14-39 7 14-22
Extension to break - Longitudinal % 11-22 3 2.5
Extension to break - Transverse % 8-17 5 2.5
Initial Tear Strength g.µm-1 12-32 2-4 6-10
Limiting Oxygen Index % 29-32 29 63
Shrinkage @ 300 °C % 0.3-2 0.2-0.3
Tensile strength - Longitudinal MPa 85-130 6 40
Tensile strength - Transverse MPa 35-75 3 30
Thermal Conductivity @ 23 °C W.m-1.K-1 0.1-0.16
Properties Polyaramid Honeycomb
Property Value
Cell Size mm 6 5 3 5
Compressive Strength MPa 0.7 1.1 2.2 3.8
Core Density g.cm-3 0.024 0.032 0.048 0.064
Plate Shear Modulus - Longitudinal MPa 25 34 52 70
Plate Shear Modulus - Transverse MPa 14 20 29 35
Plate Shear Strength - Longitudinal MPa 0.7 1.1 1.8 2.5
Plate Shear Strength - Transverse MPa 0.35 0.6 0.9 1.1
Wall Thickness mm 0.05 0.05 0.05 0.08
Properties Polyaramid Sheet
Property Value
Material T992 T993 T994
Density g.cm-3 0.5 0.83 1.14
Dielectric Constant @ 60 Hz 1.7 ~3.5 ~4.4
Dielectric Strength @ 3 mm thick KV.mm-1 15-32 ~33-66 ~25-70
Dissipation Factor @ 60 Hz 0.02 ~0.09 ~0.02
Extension to break - Longitudinal % 3 5.5
Extension to break - Transverse % 4 7
Limiting Oxygen Index % 29 32
Tensile strength - Longitudinal MPa 14.5 56 120
Tensile strength - Transverse MPa 11 32 70
Thermal Conductivity @ 23 °C W.m-1.K-1 0.07
Properties Polyaramid Fibre
Property Value
Specific Modulus cN/tex 1100
Specific Tenacity cN/tex 35 - 44
Density g.cm-3 1.38
Extension to break % 16 - 25
Properties Polyaramid Chopped Fibre
Property Value
Specific Modulus cN/tex 1100
Specific Tenacity cN/tex 35 - 44
Density g cm-3 1.38
Extension to break % 16 - 25

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