Dynamic Mechanical Analysis (DMA)
Dynamic Mechanical Analysis measures the mechanical properties of materials as a function of time, temperature, and frequency. The Q800 DMA instrument incorporates unique technology to provide the ultimate in performance, versatility, and ease-of-use. State-of-the-art non-contact, linear drive motor technology in our DMA instruments provides precise stress control. Ultra sensitive optical encoder technology is used to measure strain and air bearing technology insures virtually friction-free movement. The combination of these technologies sets the Q800 apart from competitive instruments that use conventional stepper motors, LVDT strain measurement devices, and mechanical springs. The Q800 DMA instrument operates over a wide temperature range (-150 to 600°C) and provides multiple modes of deformation including dual/single cantilever and 3-point bending, tension, compression, and shear. The clamps are individually calibrated for data accuracy and the elegant but simple design facilitates sample mounting.
Gas Cooling Accessory
The Gas Cooling Accessory (GCA) extends the operating range of the Q800 to -150°C. The GCA uses cold nitrogen gas generated from controlled evaporation of liquid nitrogen. Automated filling of the GCA tank can be programmed to occur after the scan is complete. The GCA will provide ballistic or controlled cooling rates over the entire operating range of the Q800 DMA (-150 to 600°C). In general, the maximum cooling rate is a function of the installed clamp and the thermal characteristics of the sample. The figure below shows the typical range* of controlled cooling rates available as a function of temperature.
The Q800 uses a non-contact, direct drive motor to provide the oscillatory or static force required. The motor is constructed of high performance composites that ensure low compliance and is thermostated to eliminate heat build-up even when using large oscillation amplitudes and high deformation forces. Sophisticated electronics enable the motor current to be rapidly adjusted in small increments. The motor can deliver reproducible forces over a wide range and the force can be changed rapidly, enabling a broad spectrum of material properties to be measured.
The non-contact drive motor transmits force directly to a rectangular air bearing slide. The slide is guided by eight porous carbon air bearings grouped into two sets of four near the top and bottom of the slide. Pressurized air or nitrogen flows to the bearings forming a frictionless surface that permits the slide to “float.” The slide, which connects to the drive shaft and sample clamp, can move vertically 25 mm and its rectangular shape eliminates any twisting of the sample. Very weak materials like films and fibers can be characterized with ease.
The Q800 features a bifilar wound furnace with automated movement. The furnace design, combined with the Gas Cooling Accessory, provides for efficient and precise temperature control over the entire temperature range, both in heating, cooling, and isothermal operation. The automatic furnace movement simplifies experimental setup.
A high-resolution linear optical encoder is used to measure displacement on the Q800 DMA. Based on diffraction patterns of light through gratings (one moveable and one stationary), optical encoders provide exceptional resolution compared to typical LVDT technology. Due to the excellent 1 nanometer resolution of the optical encoder, very small amplitudes can be measured precisely. This, combined with the non-contact drive motor and air bearing technology, provides excellent modulus precision and high tan δ sensitivity allowing the Q800 DMA to characterize a broad range of materials.
Low Mass, High Stiffness Sample Clamps
The Q800 features a variety of sample clamps that provide for multiple modes of deformation. The clamps are optimized using finite element analysis to provide high stiffness, with low mass, and attach to the drive shaft with a simple dovetail connection. The clamps are easy to use and adjust, and each is individually calibrated to ensure data accuracy. A broad range of samples can be analyzed. The high stiffness minimizes clamp compliance, and the low mass ensures rapid temperature equilibration. These simple, yet elegant designs reduce the time necessary to change clamps and load samples.
Rigid Aluminum Casting
The Q800 drive motor, air bearing slide assembly with optical encoder and air bearings are all mounted within a rigid aluminum casting that is temperature controlled. The rigid aluminum housing minimizes system compliance and the temperature-controlled housing ensures precise data.