ASTM D1646-15
Standard Test Methods for Rubber&x2014;Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)

Standard No.

ASTM D1646-15

Release Date

2015

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM D1646-17

Latest

ASTM D1646-19a

Scope

5.1 Viscosity—Viscosity values determined by this test method depend on molecular structure, molecular weight, and non-rubber constituents that may be present. Since rubber behaves as a non-Newtonian fluid, no simple relationship exists between the molecular weight and the viscosity. Therefore, caution must be exercised in interpreting viscosity values of rubber, particularly in cases where molecular weight is very high. For example, as the molecular weight increases, the viscosity values for IIR polymers (butyl rubbers) reach an upper limit of about 80, at 100°C (212°F) using a large rotor at a rotation speed of 2 r/min, and may then decrease to considerably lower values. For these higher molecular weight rubbers, better correlation between viscosity values and molecular weight is obtained if the test temperature is increased.

5.2 Stress Relaxation—The stress relaxation behavior of rubber is a combination of both an elastic and a viscous response. Viscosity and stress relaxation behavior do not depend on such factors as molecular weight and non-rubber constituents in the same way. Thus both of these tests are important and complement each other. A slow rate of relaxation indicates a higher elastic component in the overall response, while a rapid rate of relaxation indicates a higher viscous component. The rate of stress relaxation has been found to correlate with rubber structure characteristics such as molecular weight distribution, chain branching, and gel content.

5.3 Pre-Vulcanization Characteristics—The onset of vulcanization can be detected with the Mooney viscometer as evidenced by an increase in viscosity. Therefore, this test method can be used to measure incipient cure (scorch) time and the rate of cure during very early stages of vulcanization. This test method cannot be used to study complete vulcanization because the continuous rotation of the disk will result in slippage when the specimen reaches a stiff consistency.

1.1 These test methods cover procedures for measuring a property called Mooney viscosity. Mooney viscosity is defined as the shearing torque resisting rotation of a cylindrical metal disk (or rotor) embedded in rubber within a cylindrical cavity. The dimensions of the shearing disk viscometer, test temperatures, and procedures for determining Mooney viscosity are defined in these test methods.

1.2 When disk rotation is abruptly stopped, the torque or stress on the rotor decreases at some rate depending on the rubber being tested and the temperature of the test. This is called “stress relaxation” and these test methods describe a test method for measuring this relaxation.

Note 1: Viscosity as used in these test methods is not a true viscosity and should be interpreted to mean Mooney viscosity, a measure of shearing torque averaged over a range of shearing rates. Stress relaxation is also a function of the test configuration and for these test methods the results are unique to the Mooney viscometer.

1.3 When compounded rubber is placed in the Mooney viscometer at a temperature at which vulcan......

ASTM D1646-15 Referenced Document

• ASTM D1349 Standard Practice for Rubber-Standard Temperatures for Testing
• ASTM D1418 Standard Practice for Rubber and Rubber Latices-Nomenclature
• ASTM D1485 Standard Test Methods for Rubber from Natural Sources-Sampling and Sample Preparation
• ASTM D3182 Standard Practice for Rubber-Materials, Equipment, and Procedures for Mixing Standard Compounds and Preparing Standard Vulcanized Sheets
• ASTM D3185 Standard Test Methods for Rubber-Evaluation of SBR (Styrene-Butadiene Rubber) Including Mixtures With Oil
• ASTM D3186 Standard Test Methods for Rubber-Evaluation of SBR (Styrene-Butadiene Rubber) Mixed With Carbon Black or Carbon Black and Oil
• ASTM D3896 Standard Practice for Rubber From Synthetic Sources-Sampling
• ASTM D4483 Standard Practice for Determining Precision for Test Method Standards in the Rubber and Carbon Black Industries
• ISO 289 Rubber, unvulcanized; Determination of Mooney viscosity

ASTM D1646-15 history

• 2019 ASTM D1646-19a Standard Test Methods for Rubber-Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 2019 ASTM D1646-19 Standard Test Methods for Rubber—Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 2017 ASTM D1646-17 Standard Test Methods for Rubber—Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 2015 ASTM D1646-15 Standard Test Methods for Rubber&x2014;Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 2007 ASTM D1646-07(2012) Standard Test Methods for Rubbermdash;Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 2007 ASTM D1646-07 Standard Test Methods for Rubber-Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 2006 ASTM D1646-06 Standard Test Methods for Rubber-Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 2004 ASTM D1646-04 Standard Test Methods for Rubber8212;Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 2003 ASTM D1646-03a Standard Test Methods for Rubber8212;Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 2003 ASTM D1646-03 Standard Test Methods for Rubber8212;Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 2000 ASTM D1646-00 Standard Test Methods for Rubber-Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)
• 1992 ASTM D1646-92 Standard Test Method for RubberÐViscosity and Vulcanization Characteristics (Mooney Viscometer)
• 1981 ASTM D1646-81 Standard Test Method for Rubber - Viscosity And Vulcanization Characteristics ( Mooney Viscometer)