Abstract: A sealless die assembly with a backing element is disclosed. A first die assembly cooperates with a second die assembly to form a sample-holding chamber. At least one of the die assemblies includes a die and a housing that are separated from one another by a radial gap such that the die is rotatable relative to its housing. A thin film is positioned to bridge the gap between the die and its housing to maintain pressure in the sample-holding chamber. A backing element cooperates with the die housing to interface with the film, and the backing element is spaced from its corresponding die. The backing element helps to transfer torque from the sample to the torque transducer. The die assembly may be incorporated into a rheometer or other sampling measuring apparatus for testing process characteristics of a material.

Abstract: A sealless die assembly with a backing element is disclosed. A first die assembly cooperates with a second die assembly to form a sample-holding chamber. At least one of the die assemblies includes a die and a housing that are separated from one another by a radial gap such that the die is rotatable relative to its housing. A thin film is positioned to bridge the gap between the die and its housing to maintain pressure in the sample-holding chamber. A backing element cooperates with the die housing to interface with the film, and the backing element is spaced from its corresponding die. The backing element helps to transfer torque from the sample to the torque transducer. The die assembly may be incorporated into a rheometer or other sampling measuring apparatus for testing process characteristics of a material.

Abstract: A rheometer die with a groove configuration for reducing sample slippage in a rheometer chamber is provided. The rheometer die includes a surface and at least one radial groove extending into the surface. The groove defines at least a portion of a sample-holding chamber constructed to hold a sample. The groove may include a first zone and a second zone with a transition zone therebetween. The groove may also include a substantially wedge-shaped portion with sidewalls which taper generally towards the center of the rheometer die such that imaginary extensions of the sidewalls intersect before reaching the center of the die. A plurality of grooves may extend into the rheometer die. The rheometer die may be incorporated into a rheometer for testing process characteristics of a material.

Abstract: A rheometer die with a groove configuration for reducing sample slippage in a rheometer chamber is provided. The rheometer die includes a surface and at least one radial groove extending into the surface. The groove defines at least a portion of a sample-holding chamber constructed to hold a sample. The groove may include a first zone and a second zone with a transition zone therebetween. The groove may also include a substantially wedge-shaped portion with sidewalls which taper generally towards the center of the rheometer die such that imaginary extensions of the sidewalls intersect before reaching the center of the die. A plurality of grooves may extend into the rheometer die. The rheometer die may be incorporated into a rheometer for testing process characteristics of a material.

Abstract: An improved method and apparatus for measuring the properties of thermoset plastics and viscoelastic materials. The present invention includes a seal member which inhibits the release of sample material from the die cavity of a test instrument. As a result, sufficient sample material is maintained within the die cavity when pressure is applied to the material. Accordingly, an appropriate shearing force can be applied to the sample material to obtain torque measurements. Moreover, by inhibiting the release of sample material from the die cavity, sample material is prevented from coming into contact with components of the test instrument outside the die cavity, which in turn may distort or invalidate measurements of torque.

Abstract: Method and apparatus for measuring viscous heating/heat build-up of viscoelastic materials, such as rubber and polymer compounds. Temperature changes in the viscoelastic material are measured during application of a shearing force to the viscoelastic material. The shearing force is applied by rotating a second die plate relative to a first die plate, which remains stationary. Temperature changes in the viscoelastic material attributable to friction between the first die and an adjacent sealing ring are accounted for, and subtracted out of the final temperature values. The present invention provides an accurate, quantifiable, and repeatable measure of viscous heating/heat build-up of a viscoelastic material.

Abstract: A method and apparatus for testing samples of viscoelastic materials are shown, in which the sample is subjected to a sinusoidal excitation and the response to the excitation is measured. By sampling the response at at least three data points equally spaced through a single cycle of excitation and making the proper calculations based on the data points, the storage modulus or the loss modulus of the materials, or both, can be obtained. The apparatus includes a rotary drive, eccentric, sample holder, a rotor or moving die, a torque transducer, excitation means, response measuring means, data handler and a sampler to obtain responses at predetermined intervals.

Abstract: A method and apparatus for testing samples of viscoelastic materials are shown, in which the sample is contained under pressure between two dies and the forces involved in rotating one die with respect to the other. The method uses different frequencies of oscillatory rotation at different temperatures. The apparatus uses dies with discontinuous protrusions which overlap each other.