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Vespel/Polyimide


Vespel/Polyimide

DuPont Vespel is a high-performance polyimide resin. Vespel performs well with or without lubrication under conditions which would destroy other plastics or severely wear many metals. Vespel parts function over a wide range of temperatures and stresses. Vespel retains its outstanding creep, abrasion resistance, and strength under adverse conditions.Since DuPont Vespel does not soften and is thermally resistant, it can carry loads at temperatures beyond the reach of most plastic materials and do so while exhibiting extremely low creep.

The extraordinary properties of Vespel, a DuPont product made of high-performance SP polyimide resin, make it the optimal choice for tough applications such as parts used in automobiles, heavy-duty off-road equipment, jet engines and semiconductors. Vespelis not brittle, even at -400° F. It also performs continuously at temperatures up to 600° F and intermittently up to 1,000° F. Vespelcan operate at extremely high PVs. Special metalworking equipment and techniques are not needed to machine this product. Typical Vespelparts include bearings, bushings, insulators, gaskets and thrust washers.

Vespelis one of the highest performing engineering plastics currently available. Vespelwill not melt and can operate continuously from cryogenic temperatures to 550°F (288°C), with excursions to 900°F (482°C). Vespelparts consistently exhibit superior performance in a variety of applications requiring low wear and long life in severe environments.

Properties

  • Continuous performance at up to 600°F
  • No special machining equipment required
  • Dimensionally stable
  • Operates at very high PVs
  • Does not become brittle even at subzero temperatures
  • Low wear and friction at high pressures and velocities.
  • Outstanding creep resistance                                    
  • Lubricated or unlubricated performance                              
  • Excellent impact resistance                                        
  • Continuous operation at 500 degrees F                  
  • Excursions to 900 degrees F                        

Applications

Air and inert environments at 700 degrees, Service with liquid hydrogen, Nuclear radiation exposure, Mechanical applications where little or no lubricant is present, Rotary seal rings, Thrust washers and discs, Bushings, Flanged bearings, Plungers, Printer wire guides, Spline couplings, Wear strips, Valve seats, Thermal and electrical insulators, Wafer clamping, polishing and grinding rings, Wafer guides & carriers, Vacuum pads, Die pickup collets.

Vespel is the trademark of a range of durable high-performance polyimide-based plastics manufactured by DuPont. This high performance polymer is mostly used in aerospace, semiconductor and transportation technology. Unlike most plastics, it does not produce significant outgassing even at high temperatures, which makes it useful for lightweight heat shields and crucible support. It also performs well in vacuum applications, down to extremely low cryogenic temperatures. However, Vespel tends to absorb a small amount of water, resulting in longer pump time while placed in a vacuum.

Although there are polymers surpassing polyimide in all of these properties, the combination of them is the main advantage of Vespel.

Grades and Colors

VespelSP-21

For VespelSP-21, 15% graphite by weight is added to the base resin for increased wear resistance and reduced friction in applications such as bearings, thrust washes, bushings, seal rings, slide blocks and other wear surfaces. VespelSP-21 has the highest mechanical properties of the graphite-filled grades.

VespelSP-22

For VespelSP-22, 40% graphite by weight is added to the base resin for enhanced resistance to wear and friction and good dimensional and oxidative stability. VespelSP-22 has the lowest coefficient of thermal expansion of the graphite-filled grades. Typical applications are the same as those for VespelSP-21.

VespelSP-211

For VespelSP-211, 10% Teflon(PTFE) and 15% graphite by weight are added to the base resin for the lowest coefficient of friction over a wide range of operating conditions. VespelSP-211 also has excellent wear resistance up to 300° F. Typical applications include sliding or linear bearings as well as many of the wear and friction applications for which the other Vespelgrades are suitable.

VespelSP-3

For VespelSP-3, 15% molybdenum disulfide by weight is added to the base resin for wear and friction resistance in vacuum and other moisture-free environments where graphite actually becomes abrasive. Typical applications include seals, bushings, bearings, gears and other wear surfaces in outer space and in ultra-high vacuum or dry-gas environments.

Vespel is a registered trademark of E.I. Dupont

                                         TYPICAL PROPERTIES OF VESPEL POLYIMIDE

ASTM or UL test

Property

SP-1

SP-21

SP-22

SP-211

SP-3

-

Filler Material

Unfilled

15% Graphite

40% Graphite

10% PTFE,15% Graphite

15% Moly

PHYSICAL

D792

Density (lb/in³) (g/cm³)

0.051

 1.43

0.055

 1.51

0.060

 1.65

0.056

 1.55

0.058

 1.60

D570

Water Absorption, 24 hrs @ 73°F (%)48 hrs @ 122°F (%)

0.24

 0.72

0.19

 0.57

0.14

 0.42

0.21

 0.49

0.23

 0.65

MECHANICAL

D638

Tensile Strength, Ultimate @ 73°F (psi) @ 500°F (psi)

12,500 6,000

9,500

5,500

7,500

3,400

6,500

3,500

8,200

-

D638

Tensile Modulus (psi)

-

-

-

-

-

D638

Tensile Elongation, Ultimate @ 73°F (%)@ 500°F (%)

7.5

6.0

4.5

6.0

3.0

2.0

3.5

3.0

4.0 -

D790

Flexural Strength, Ultimate @ 73°F (psi) @ 500°F (psi)

16,000 9,000

16,000 9,000

13,000 6,500

10,000 5,000

11,000 5,500

D790

Flexural Modulus @ 73°F (psi) @ 500°F (psi)

450,000 250,000

550,000 370,000

700,000 400,000

450,000 200,000

475,000 270,000

D695

Compressive Strength, 10% strain @73°F (psi)

19,000

19,300

16,300

14,800

18,500

D695

Compressive Modulus (psi)

350,000

420,000

475,000

300,000

350,000

D785

Hardness,Rockwell

E45-60

E25-45

E5-25

E1-20

E40-55

D256

 IZOD Notched Impact (ft-lb/in

0.8

0.8

-

-

0.4

-

Poisson's Ratio

0.4

0.4

-

-

-

THERMAL

D696

Coefficient of Linear Thermal Expansion(x 10^-5 in./in./°F)

3.0

2.7

2.1

3.0

2.9

D648

Heat Deflection Temp (°F/°C) at 264 psi

680 / 360

680 / 360

-

-

-

-

Max Continuous Operating Temp (°F/°C)

500 / 260

500 / 260

500 / 260

500 / 260

500 / 260

C177

Thermal Conductivity (BTU-in/ft²-hr-°F) (x 10-4 cal/cm-sec-°C)

2.0

6.9

6.0

20.7

12.0

41.3

5.3

18.3

3.2

11.0

UL94

Flammability Rating

V-0

V-0

V-0

V-0

V-0

D149

Dielectric Strength (V/mil) short time, .08" Thick

560

250

-

-

-

D150

Dielectric Constant at 1 MHz

3.55

13.2

-

-

-

D150

Dissipation Factor at 1 MHz

0.0034

0.0106

-

-

-

D257

Volume Resistivity (ohm-cm)at 50% RH

10^14 -10^15

10^12-10^13

-

-

-

 Vespel/Polyimide Pictures