Snapidle - Ultra-High Molecular Material Data


Ultra-High Molecular Material (UHMW) Data

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 -

Chemical Resistance

Test Specimens: Dumb-bell Type; Duration of Test: 30 days

  1. Resistant: Mechanical properties not appreciably affected
  2. Limited Resistance: Decrease in yield stress and ultimate tensile strength less than 20%
  3. 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

"The Snapidle chain tensioner is easier to install and maintain than the adjustable sprocket tensioner. The Snapidle is generally made out of UHMW-PE and stainless steel hardware with the strap having the option of being stainless steel. It is self-adjusting because of its unique design that allows it to slide up and down the drive chain wherever there is slack. Its reliability and lack of needed maintenance make it the tensioner of choice." -Allied-Locke Industries

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