Dynamic Properties |
| In the 1960s, a version of the rheometer, model LHS, introduced by the Monsanto Company, was developed that allowed the dynamic properties of an ODR sample to be determined throughout the curing cycle [7]. |
| Although this model was widely accepted, it was severely handicapped by the manual computations required [21]. The availability of computer calculating capability would have greatly enhanced the acceptance of this early technological innovation. |
| The proposed XDR® system provides this information (S*, S', S'') through a novel signal computer processing program. This system utilizes a direct measurement of the imposed strain on the sample rather than indirect assumptive approaches. This dynamic data is readily presented graphically and numerically. |
 Figure 11
shows dynamic properties cure curve for the SBR formulation, defined in Table I, using the virtual MDR with correction for the seal contribution. |
Test Report Data & Analysis |
| In the computer monitor screen display of the dynamic properties via MDR on the SBR formulation, all the parameters in the rectangular box are displayed throughout each test. The temperatures are graphically displayed at the bottom of the screen. |
A typical computer generated test report on the SBR formulation provides a complete documentation of a single test, including:
• operator information,
• cure curve parameter results,
• operation details: temperatures, die type,
• test time, degree of arc, etc. |
| This is in addition to the graphical representation of the experimental cure curve. At the bottom of the report is an assessment of the results vs. quality control limits. |
| An overlay report on four repetitive XDR® (SBR formulation, MDR mode, 175 C°, ±0.5° normalized to ±1.0°) runs are shown in
Figure 12.
Note that the mean and 2 sigma values for each test parameter is calculated. This is invaluable information for establishing control limits for routine quality control. |
Mooney Viscometer |
| The XDR® rheometer can easily be converted to a Shearing Disk Viscometer by interchanging a few key components. |
|
| The curemeter central shaft and bearing system is replaced by the Mooney conversion module. |
| This module consists of the central shaft, bearings, sample ejector, and auto dead weight calibration system. This module is completely preassembled for easy conversion. The same force transducer and connecting links are repositioned to measure the reaction torque sensed by the drive motor as a result of the changing viscosity of the test sample. |
| The Mooney die and rotor are direct replacements for the corresponding elements of the curemeter. These few simple steps converts the XDR® from an ODR / MDR to a Mooney. |
| XDR® Mooney viscosity / stress relaxation and Mooney scorch tests conform to ASTM D1646 [22]. |
Conclusions |
| The XDR® “three—instruments—in—one” test instrument concept and design has been presented. This capability can be depicted as follows: |
| XDR® » ODR (heated rotor) «» MDR «» Mooney |
| It has been confirmed that the design “flaw” which makes the ODR yield longer cure times than the MDR, is a “cold rotor”. An ODR with the patented heated rotor, has been shown to yield cure parameters approaching those obtained with an MDR type curemeter. |
| In addition, it has been found that system deflections in the ODR continually reduce the magnitude of the strain arc imposed on the test sample, as the torque increases. The major source of this deflection has been identified and a procedure for correction incorporated into the XDR®. |
| The simplified MDR, a “virtual” MDR, configuration provides for easy sample removal and an improvement in overall performance. The ODR can be easily converted to the novel MDR and / or a Mooney viscometer by simple rearrangement of removable modules. |
| This capability of interchangeability of instruments is made possible as a result of the operating principals common to the three instruments combined with a computerized operating system that can be used for each of the three configurations. |
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Reference