ASTM D1646-2015
橡胶的标准试验方法. 粘度, 应力松驰及预硫化特性 (穆尼粘度计)

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

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标准号

ASTM D1646-2015

发布日期

2015年

实施日期

废止日期

无

国际标准分类号

83.060

发布单位

美国材料与试验协会

适用范围

5.1x00a0;Viscosityx2014;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 100x00b0;C (212x00b0;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.

5.2x00a0;Stress Relaxationx2014;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.

5.3x00a0;Pre-Vulcanization Characteristicsx2014;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.

1.1x00a0;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.

1.2x00a0;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 x201c;stress relaxationx201d; and these test methods describe a test method for measuring this relaxation.

Note 1:x00a0;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.

1.3x00a0;When compounded rubber is placed in the Mooney viscometer at a temperature at which vulcan......

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