Poly­imide [Meldin®, Vespel®]


  • High-performance poly­imide mate­r­ial formed from resin
  • Does not melt
  • Can oper­ate con­tin­u­ously from cryo­genic tem­per­a­tures to 550°F, with excur­sions up to 900°F
  • Low wear, long life in severe environments
  • Dimen­sion­ally stable
  • Radiation-resistant
  • Extremely low outgassing
  • Rel­a­tively easy to machine
  • Avail­able in fives grades: Vespel SP-1 (unfilled base resin grade), Vespel SP-21 (15% graphic by weight added to the base resin for improved wear resis­tance), Vespel SP-22 (40% graphite by weight added for enhanced wear resis­tance, less fric­tion and improved dimen­sional sta­bil­ity), Vespel SP-211 (10% PTFE and 15% graphite by weight for the low­est coef­fi­cient of fric­tion), and Vespel SP-3 (15% molyb­de­num disul­fide lubricant-filled for wear and fric­tion resis­tance in vac­uum and other moisture-free envi­ron­ments in which graphite becomes abrasive).

Com­mon uses

  • Rotary seal rings
  • Thrust wash­ers and discs
  • Bush­ings
  • Flanged bear­ings
  • Printer wire guides
  • Wear strips
  • Wafer clamp­ing, pol­ish­ing and grind­ing rings
  • Vac­uum pads


Mate­r­ial Specifications

ASTM or UL test Prop­erty SP-1
D792 Den­sity (lb/in3)/(g/cm3) 0.051 (1.43)
D570 Water absorp­tion, 24 hrs (%) 0.24
D638 Ten­sile strength (psi) 12,500
D638 Ten­sile mod­u­lus (psi) -
D638 Ten­sile elon­ga­tion at break (%) 7.5
D790 Flex­ural strength (psi) 16,000
D790 Flex­ural mod­u­lus (psi) 450
D2176 Fold­ing endurance (cycles) 5–80 x 103
D785 Hard­ness, Rockwell 50
D256 Izod notched impact (ft-lb/in) 0.8
D696 Coef­fi­cient of lin­ear ther­mal
expan­sion (x 10–5 in./in./°F)
D648 Heat deflec­tion temp (F°) at 264 psi 680
D3418 Melt­ing temp (F°/C°) -
- Max oper­at­ing temp (F°/C°) 500/260
C177 Ther­mal con­duc­tiv­ity
UL94 Flam­ma­bil­ity rating V-O
D150 Dielec­tric con­stant at 1 MHz 3.55
D150 Dis­si­pa­tion fac­tor at 1 MHz 0.0034
D149 Dielec­tric strength (V/mil) 560
D257 Vol­ume resis­tiv­ity (ohm/cm) at 50% RH 1014 - 1015

These are typ­i­cal val­ues for ref­er­ence and com­par­i­son only. They should not be used as a basis for design spec­i­fi­ca­tions or qual­ity con­trol. Con­tact us for the man­u­fac­tur­ers’ com­plete mate­r­ial prop­erty datasheets. All val­ues were taken at 73°F (23°C) unless oth­er­wise noted.

Don’t see what you’re look­ing for? Call us at 800–423-2769 or email us at tom@crownplasticsinc.com.