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Millathane® 97

A Transparent Millable Polyurethane Rubber

Clearly Superior.  Millathane® 97 is designed for applications in shoe soling, roll coverings and other applications where transparency in brightly colored or decorative products is required.  It's a polyether millable urethane rubber having excellent wear properties, a high coefficient of friction and very good UV stability.

For more information about Millathane® and Thanecure® products, please contact: Lynn Zylka at (727) 540-1358 or contact Lynn here.

Product Description

Chemical Composition: Synthetic rubber based on ether/aliphatic diisocyanate
Specific Gravity: Approximately 1.02 g/cc
Mooney Viscosity: 40 to 80 ML 1+4 @ 100º C
Appearance: Clear to slightly amber bales
Package: 38 pounds per box
Storage stability 3 years when stored under dry and cool conditions



Millathane® 97 rubber is typically formulated with reinforcing fillers (e.g. fumed silica for transparent compounds), along with peroxide curatives and other additives, and mixed on an open mill or in an internal mixer.  Molded articles can be produced via compression, transfer or injection molding.  See TIPS V3-1 for Injection Molding of Millathane 97.


Millathane 97 is peroxide-curable only, and Varox/Luperox 231 or DiCup R are generally used. Coagents such as SR231 (DEGDMA) and/or SR350 (TMPTMA) from Sartomer are commonly used to improve cure rates and physical properties. They also improve processing because they are liquid materials, acting as plasticizers during mixing. Millathane 97 requires reinforcing fillers to achieve hardness and high mechanical strength. A reinforcing filler like fumed silica (e.g., Wacker HDK N20) is typically used to achieve clear compounds, and is easily incorporated into Millathane 97. A small amount, ~0.25 phr, of antioxidant¹ should be used in all compounds. For good weather and UV resistance, especially for clear compounds, a UV absorber² and a Hindered Amine Light Stabilizer³ (HALS) should also be used, at ~0.25 phr each. For higher heat resistance, 2 phr of antioxidant, along with the two UV stabilizers noted, should be used, although some yellowing may be a result.

¹ Songnox 1010 or Irganox 1010; ² Songsorb 3280 or Tinuvin 328; ³ Sabostab UV65 or Tinuvin 765


Vulcanizates based on Millathane 97 can be produced in hardnesses ranging from 45 to 95 Shore A durometer, and offer exceptional clarity, outstanding abrasion resistance, good chemical resistance and an excellent hydrolysis resistance. Millathane 97 shows an improvement in low temperature flexibility and wet traction compared to previous grades of clear polyurethane rubber.

Vulcanization Conditions

Compounds based on Millathane 97 are vulcanized at temperatures of 145º - 165º C, depending on the peroxide used, with typical curing times of compression molded lab sheets being 5 to 10 minutes.

Formulation Example

(See the Millathane Formulary for other compound examples)
Millathane 97100.00
Stearic Acid0.25
Wacker HK-N20 fumed silica30.00
Irganox 1010 0.30
Silquest A-1720.25
Ultramarine blue0.01
SR231 3.00
Lupersol231 (or Varox 231) 0.40
Cure Time, minutes10
Cure Temperature150º C
Hardness, Shore A70
100% Modulus, MPa (psi) 2.6 (377)
200% Modulus, MPa (psi) 5.7 (825)
300% Modulus, MPa (psi) 10.1 (1460)
Tensile Strength, MPa (psi) 26.1 (3780)
Elongation at break, % 490



Millathane® 97 Compounds
Hardness, Shore A ID/Link Description
35 1694 Clear Molding Compound
41 (62 Asker C) XP6158E Non-Black Sponge/Foam Compound 0.53 g/cc density
47 1763

Clear Molding Compound

65 2222

Clear Shoe Sole Compound

72 1676 BLACK Molding Compound
78 708

Clear Diaphragm

91 709

Clear Molding Compound