PI (POLYIMIDE)
VESPEL® SP   MELDIN®   ENVEX®

SPECIFICATIONS:

U.S. MILITARY MIL-R-46198
AMS 3644

NATURAL COLOUR:
   LIGHT BROWN

Yet another of the high strength, high temperature resistant thermoplastic polymers, POLYIMIDES are also characterized by very low creep particularly at high temperature, very good wear resistance, quite good electrical insulation properties, very good radiation resistance, non-burning and dimensional stability. As well, POLYIMIDES are transparent to microwaves making them useful for high temperature transducers. But, very high cost has also characterized POLYIMIDE stock shapes. This fact has spurred the development of other high temperature resistant, high strength polymers. Direct forming by sintering reduces the cost of parts but physical properties are much lower. Although the chemical resistance of POLYIMIDES to most organics and dilute acids is very good; bases including alkali, ammonia and hydrazine plus strong oxidizing agents attack POLYIMIDES. As well, water or steam above atmospheric boiling point will cause hydrolytic degradation. Grades using a variety of fillers, usually designed to enhance tribiological properties, are available allowing PV values, with lubrication, up to 106! POLYIMIDES machine well using carbide or diamond tooling at high speed, with fine finishing cuts. Only water is suitable as a coolant and dry machining is preferred. POLYIMIDES are bondable using polar adhesives.

GENERAL PROPERTIES
  ASTM
test		 Unfilled 15% Graphite 30% Graphite 10% PTFE
15% Graphite
SPECIFIC GRAVITY   D792 1.34 1.42 1.46 1.50
TENSILE STRENGTH psi D638 18700 9500 5600 5000
TENSILE MODULUS 105 psi D638 3.17 2.86 2.89  
ELONGATION % D638 9.1 4.8 3.4 3.2
FLEXURAL STRENGTH psi D790 24500 18700 10800 8700
FLEXURAL MODULUS 105 psi D790 5.04 5.33 5.66 3.90
COMPRESSIVE STRENGTH 10% psi D695 29100 25300 17000 16200
COMPRESSIVE MODULUS 105 psi D695 3.73 3.93 3.60 3.25
HARDNESS rockwell M D785 M122 M110 M103 M100
IMPACT STRENGTH (1/2" x 1/2") ft-lb/inch of notch D256 0.6 0.6 0.6 0.3
THERMAL EXPANSION 10-5/°F D696 2.6 2.3 2.2 3.0
HEAT RESISTANCE
(continuous in air)		 °F   500 500 500 500
DEFLECTION TEMPERATURE   D648        
@ 264 psi °F   580 570 575 550
@ 66 psi °F   N/A N/A N/A N/A
DIELECTRIC STRENGTH v/mil D149 560 N/A N/A N/A
DIELECTRIC CONSTANT   D150 3.27 to 3.43 N/A N/A N/A
DISSIPATION FACTOR 10-3 D150 1.8 to 5.9 N/A N/A N/A
WATER ABSORPTION 24hrs % D570 0.24 0.19 0.14 0.21
FLAMMABILITY in/min D635 <0.1 <0.1 <0.1 <0.1
BEARING PROPERTIES
WEAR FACTOR, 'K' 10-10-in3-min
ft-lb-hr		 D3702 32 17 19 4
COEFFICIENT of FRICTION (DRY)            
against self - static 40 psi          
against self - dynamic 40 psi/50fpm          
against steel - static 40 psi   0.37 0.30 0.27 0.20
against steel - dynamic 40 psi/50fpm   0.32 0.24 0.30 0.15
LIMITING PV lb-ft/in2-min @10fpm 375000 375000 375000 200000
    @40fpm 375000 375000 375000 200000
    @100fpm 375000 375000 375000 200000
    @400fpm 375000 375000 375000 200000
    @1000fpm 375000 375000 375000 200000

PLEASE NOTE:
Values shown in the above table are averages and there will be variances from lot to lot. After selecting a material based upon these values, you must conduct tests specific to your application to be assured the material suits your needs.