Rubber Process Analyser
The TA Instruments RPA elite rubber process analyzer (RPA) is the most advanced rotorless rotational shear rheometer dedicated to the complete characterization of polymers, rubber and rubber compounds at all stages of manufacture. The RPAelite provides invaluable viscoelastic data on materials that are uncured, through the curing process, and in situ cured materials. The ultra-rigid test frame, high-resolution variable direct drive motor, ultra-stiff wide-range torque transducer, and precision temperature control provide the most precise and accurate torque, viscosity and viscoelastic properties of elastomers over the widest ranges of testing conditions. The fully flexible architecture of the RPA elite enables advanced testing capabilities beyond any other rubber rheometer including: complete post cure viscoelastic characterization, fully programmable sealing pressure, large amplitude oscillatory shear (LAOS) and arbitrary waveform deformations.
The most advanced design for testing flexibility and unmatched data precision and accuracy
High resolution variable direct drive motor for absolute strain control
Proprietary high stiffness, wide torque range transducer with high sensitivity for noise free data
Extremely rigid test frame for accurate compliance-free data
Fully programmable testing parameters and methods including: strain, frequency, temperature, time, and sealing pressure
Widest range and combination of tests and testing conditions available
Pneumatic locking cylinders with adjustable platen closing force and pressure sensor
Available autosampler for unattended operation
User calibration and user replaceable seals
Rigid Testing Platform
The RPA elite is built with an ultra-stiff testing frame and crosshead which eliminate the effects of instrument compliance on test data. Instrument compliance, or instrument deformation, produces erroneously low values of measured properties such as modulus and torque, irregular strain and torque waveform signals, and other errors.
Large diameter steel rods and a thick crosshead brace in the H-shaped load frame of the RPA elite provide unmatched rigidity to resist instrument deflection while the motor deforms the sample. This special design ensures that the commanded strain is achieved with each cycle of deformation, even for highly filled, fully cured rubbers. Additionally, a non-compliant system allows for truly sinusoidal strain profiles under all conditions. This can be verified by continuous Fourier Transform analysis of the deformation and measured torque signals which is available in the Scarabaeus Software. The superior design also guarantees smooth travel, proper alignment, and precise application of vertical load.
Direct Drive Motor
A powerful direct drive motor applies precise deformation in the RPA elite. A high quality rheological or dynamic measurement relies on the precise application of a constant rate, step, or periodic deformation. In a direct drive system the start-up delays, compliance, and translational losses seen in clutch or belt driven configurations are eliminated. The superior motor design of the RPA elite ensures that the most accurate and repeatable deformations are always applied to the sample.
The RPA elite applies the highest combination of continuously variable frequency and amplitude in any rubber rheometer. This provides important material information such as:·
The linear viscoelastic response of highly filled rubbers at low strains
Behaviour at extreme processing and use conditions characterized by high strains
Terminal material behaviour exhibited at low frequencies
Response to high speed deformations measured at high frequencies
Advanced Data Processing
The complex deformations and stress-strain response common to rubber testing demand the most advanced data processing techniques. The RPA elite from TA Instruments utilizes a state-of-the-art 20 bit encoder and advanced data sampling technique to perform calculations based on a Fast Fourier Transform (FFT) analysis using 90 data points for each cycle of oscillation.The RPA elite measures and reports non-linearities in torque and displacement. Higher harmonics indicating non-linearity in the applied displacement or measured torque, are reported for each data point, alert the operator with a simple indicator if test conditions are not ideal and storing this information for subsequent data validation.
High Stiffness Torque Transducer
The RPA elite benefits from a proprietary wide range ultra-stiff torque transducer. This rugged, non-compliant device measures the widest range of torques accurately and precisely. This greatly improves the accuracy and precision of measured torque, modulus, and viscosity values.
The RPA elite is compatible with either the Standard or Enhanced Subambient Cooling System. The Standard Cooling System uses ambient air to expedite temperature changes above ambient conditions and improve temperature stability near room temperature.
The Enhanced Subambient Cooling System is a mechanical device that employspressurized air to cool the test environment, allowing characterization of rubbers at temperature as low as 18 °C and greatly accelerating cooling time between nonisothermal experiments. The system has no moving parts, making it extremely reliable and easy to use.
Dies & Rotors
The complex deformations and stress-strain response common to rubber testing demand the most advanced data processing techniques. The RPA elite from TA Instruments utilizes a state-of-the-art 20 bit encoder and advanced data sampling technique to perform calculations based on a Fast Fourier Transform (FFT) analysis using 90 data points for each cycle of oscillation.
The RPA elite measures and reports non-linearities in torque and displacement. Higher harmonics that indicate non-linearity in the applied displacement or measured torque reported for data point, alerting the operator with a simple indicator if test conditions are not ideal and storing this information for subsequent data validation.
High Pressure Pneumatic System
The RPA elite employs a high pressure pneumatic system to seal the sample properly and reproducibly. The high capacity pneumatic system applies up to 8 bar nominal pressure to the during gap closure. Proper alignment and the use of mechanical bearings ensure efficient transfer of load from the system to the sample without load frame losses. Actual sealing pressure is measured directly and recorded. This high pressure automated sample containment removes operator dependence and tightly contains the test specimen. This sealing process is particularly important for materials that undergo positive or negative volumetric changes with curing and highly stiff materials such as carbon-filled fluoroelastomers.
The RPA elite die surfaces feature an optimized arrangement of radial serrations to guarantee constant sample contact at even the highest strain values. Polyester or polyamide films may be used to facilitate sample release and avoid the need to clean dies between experiments.
Torque calibration is made simple with a certified torque calibration device. This feature allows the user to calibrate the instrument directly, increasing data confidence and operation time, and reducing the reliance of service engineers for calibration.