UHMW Data
Ultra-High Molecular Material |
 |
UHMW possesses a unique combination of physical and mechanical properties
which enable it to perform well under the most rigorous conditions of wear and
environment. It has the highest known impact strength of any thermoplastic
presently made, plus high resistance to abrasion against a wide variety of
metals. These properties make UHMW an exceptional material for industrial
impact, wear and sliding operations. UHMW is FDA compliant and USDA approved for
direct contact in food processing applications. For polyethylene to be certified
as UHMW the molecular weight of the material must be at least 4 million (4 PPM).
UHMW is usually certified at 4-6 million molecular weight. Any material with
less than a 4 million molecular weight is either high density or low density (HD
or LD) polyethylene. These products are much less expensive to manufacture than
UHMW, but the physical properties are correspondingly less. Snapidle certifies
that only polyethylene greater than a 4.2 million molecular weight is used in
Snapidle's UHMW products.
UHMW Mechanical Properties
| Property |
ASTM Test |
Units Metric (US) |
Typical Values |
| Specific Gravity |
D792 |
gm/cm° |
0.926-0.934 |
| Tensile Strength @ Yield |
D638 |
MPa (PSI) |
21 (3100) |
| Tensile Strength @ Break |
D638 |
MPa (PSI) |
48 (7000) |
| Elongation @ Break |
D638 |
% |
350 |
| Young's ("E") Modulus (23°C) |
D638 |
MPa (PSI × 105) |
690 (1.0) |
| Young's ("E") Modulus (-269°C) |
D638 |
MPa (PSI × 105) |
2970 (4.3) |
| Izod Impact Strength (23°C) |
D256(1) |
J/m (ft-LBS/in notch) |
140 (30) |
| Izod Impact Strength (-40°C) |
D256(1) |
J/m (ft-LBS/in notch) |
100 (21) |
| Hardness, Shore "D" |
D2240 |
- |
62-66 |
| Abrasion Resistance |
(2) |
- |
100 |
| Water Absorption |
D570 |
% |
Nil |
| Relative Solution Viscosity |
D4020 |
dl/gm |
2.3-3.5 |
| Density |
|
(lbs./cubic in.) |
.034 |
(1)Izod Impact Strength: Samples have two (15° ± 1/2°) notches on opposite
sides to a depth of 5mm.
(2)See description of test method - Under Sand-Slurry test results.
UHMW Thermal Properties
| Property |
ASTM Test |
Units Metric (US) |
Typical Values |
| Temperature Range |
|
°F |
-269° to 160° |
| Crystalline Melting Range, Powder |
Polarizing Microscope |
°C (°F) |
138-142 (280-289) |
| Coefficient of Linear Expansion: 20 to 100°C |
D696 |
K-1 |
~2 × 10-4 |
| Coefficient of Linear Expansion: -200 to -100°C |
D696 |
K-1 |
~0.5 × 10-4 |
UHMW Electrical Properties
| Property |
ASTM Test |
Units Metric (US) |
Typical Values |
| Volume Resistivity |
D257 |
Ohm cm |
>5 × 1016 |
| Dielectric Strength |
D149 |
KV/cm (V/mil) |
900 (2300) |
| Dielectric Constant (Er) |
D150 |
- |
2.30 |
| Dissipation Factor (tan ð) at: 50 Hz |
D150 |
- |
1.9 × 10-4 |
| Dissipation Factor (tan ð) at: 103 Hz |
D150 |
- |
0.5 × 10-4 |
| Dissipation Factor (tan ð) at: 105 Hz |
D150 |
- |
2.5 × 10-4 |
Comparison of Dynamic Coefficient of Friction on Polished Steel
| Property |
UHMW |
Nylon 6 |
Nylon 6/6 |
Nylon/MoS2 |
PTFE |
Acetal Copolymet |
| Dry |
.10-.22 |
.15-.40 |
.15-.40 |
.12-.20 |
.04-.25 |
.15-.35 |
| Water |
.05-.10 |
.14-.19 |
.14-.19 |
.10-.12 |
.04-.08 |
.10-.20 |
| Oilq.05-.08 |
.02-.11 |
.02-.11 |
.08-.10 |
.05-.05 |
.05-.10 |
- |
| -12- |
Chemical Resistance
Test Specimens: Dumb-bell Type; Duration of Test: 30 days
- A = Resistant: Mechanical properties not appreciably affected
- B = Limited Resistance: Decrease in yield stress and ultimate tensile
strength less than 20%
- C = Not Resistant: Decrease in yield stress and ultimate tensile strength
greater than 20%
I. Inorganic Acids
| Reagent |
20°C |
50°C |
80°C |
| Chromic Acid (80%) |
A |
A |
B |
| Hydrochloric Acid (conc.) |
A |
A |
A |
| Hydrocyanic Acid |
A |
A |
- |
| Hydrofluoric Acid |
A |
A |
- |
| Nitric Acid (conc.) |
C |
C |
C |
| Nitric Acid (50%) |
B |
C |
C |
| Nitric Acid (20%) |
A |
A |
B |
| Phosphoric Acid (85%) |
A |
A |
A |
| Sulfuric Acid (conc.) |
A |
C |
C |
| Sulfuric Acid (75%) |
A |
B |
B |
II. Alkalis
| Reagent |
20°C |
50°C |
80°C |
| Aqueous Ammonia |
A |
A |
- |
| Potassium Hydroxide Solution |
A |
A |
A |
| Sodium Hydroxide Solution |
A |
A |
A |
III. Aqueous Solutions of Inorganic Salts
| Reagent |
20°C |
50°C |
80°C |
| Aluminum Chloride |
A |
A |
A |
| Ammonium Nitrate |
A |
A |
A |
| Bleaching Powder |
A |
A |
A |
| Calcium Chloride |
A |
A |
A |
| Sodium Carbonate |
A |
A |
A |
| Sodium Chloride |
A |
A |
A |
| Nitric Acid (20%) |
A |
A |
A |
| Sodium Hypochlorite |
A |
A |
A |
| Zinc Chloride |
A |
A |
A |
IV. Organic Acids
| Reagent |
20°C |
50°C |
80°C |
| Acetic Acid (99%) |
A |
A |
B |
| Acetic Acid (10%) |
A |
A |
A |
| Butyric Acid |
A |
A |
- |
| Citric Acid |
A |
A |
A |
| Formic Acid |
A |
A |
- |
| Oleic Acid |
A |
A |
B |
V. Hydrocarbons & Halogenated Hydrocarbons
| Reagent |
20°C |
50°C |
80°C |
| Benzene |
B |
B |
- |
| Carbon Tetrachloride |
B |
- |
- |
| Cyclohexane |
A |
A |
- |
| Dichloroethylene |
C |
C |
- |
| Diesel Oil |
A |
A |
B |
| n-Heptane |
A |
- |
- |
| Petroleum Ether |
A |
- |
|
| Trichloroethylene |
B |
C |
- |
| Toluene |
B |
C |
- |
| White Spirit |
A |
B |
- |
| Xylene |
B |
B |
C |
VI. Alcohol, Ketones, Ester & Amines
| Reagent |
20°C |
50°C |
80°C |
| Acetone |
A |
A |
- |
| Aniline |
A |
A |
B |
| Benzyl Alcohol |
A |
A |
A |
| Butyl Alcohol |
A |
A |
- |
| Cyclohexanol |
A |
A |
A |
| Ethanol |
A |
A |
- |
| Ethyl Acetate |
A |
A |
- |
| Ethylene Glycol |
A |
A |
A |
| Glycerin |
A |
A |
A |
| Lauryl Alcohol |
A |
A |
A |
| Propyl Alcohol |
A |
A |
A |
VII. Miscellaneous
| Reagent |
20°C |
50°C |
80°C |
| Beer/Wine |
A |
A |
A |
| Detergents in Aqueous Solution |
A |
A |
A |
| Distilled Water |
A |
A |
A |
| Hydrogen Peroxide 30% (Perhydrol) |
A |
A |
- |
| Linseed Oil / Olive Oil |
A |
A |
A |
| Milk |
A |
A |
A |
| Sea Water |
A |
A |
A |
*The information contained herein is, to our best knowledge, true and
accurate, but all the recommendations or suggestions are made without guarantee,
since the conditions of use are beyond our control. We disclaim any liability
incurred in connection with the use of these data or suggestions. This
publication is not to be taken as a license to operate under, or a
recommendation to infringe any patents. The observance of all legal regulations
and patents is the responsibility of the user.
Abrasion Resistance
The abrasion resistance of UHMW is illustrated in the sand-slurry diagram
below. These tests were conducted for a period of 7 1/2 hours at a speed of 1750
rpm's. Results for convention wear resistant materials are expressed as a
percentage based on the volume of material lost. A carbon steel standard was
assigned a value of 100. The lower values represent an increased resistance to
abrasion.
Sand-Slurry Test Results
| UHMW |
44 |
Medium Density Polyethylene |
125 |
| AR Steel |
52 |
Phosphor Bronze |
190 |
| Polybutylene |
56 |
Polypropylene |
190 |
| TFE |
72 |
Phenolic Laminate L.E. |
200 |
| 304 Stainless Steel |
84 |
Polysulfone |
300 |
| Polycarbonate |
96 |
Yellow Brass |
400 |
| Carbon Steel |
100 |
Low Density Polyethylene |
530 |
| High Density Polyethylene |
109 |
Maple Wood |
690 |
| Polyacetal |
110 |
Hard Neoprene |
800 |
