Dynamic Mechanical Analysis (DMA)

Perkin Elmer DMA 8000 Dynamic Mechanical Analysis

Dynamic Mechanical Analysis (DMA) is a technique used to study and characterize materials by applying a small deformation to the sample in a cycle manner and measuring the mechanical response of the bulk material as a function of time, temperature, and frequency. DMA test conditions can be designed to study bulk mechanical properties such as elasticity, viscous response, modulus (loss modulus and storage modulus of the sample can be measured and can be evaluated separately) and damping.

Principle

The DMA 8000 produces optimal analysis head configuration for virtually any test type and sample geometry due to the rotating analysis head which can be oriented through a full 180°. The lightweight analytical train has minimum compliance which translates to enhanced performance. The quartz window present in the standard furnace causes the temperature profile and other conditions of the experiment to remain uninterrupted during the visual inspection and clamping system. Most importantly the quartz window allows the test material to be irradiated with UV-Vis for curing of the sample during the test procedure.

Strengths

• Rapid cooling and heating capability allows the sample to be tested at different temperatures
• The samples can be analysed with multiple geometry configurations (as given below) in different orientations (Horizontal, vertical)
     o Tension
     o 3-point bending
     o Cantilever (single, dual)
     o Compression
     o Shear
• DMA is also equipped with an ultra-efficient cooling system which allows the sample to be cooled to -190 C (without immersion) rapidly with a low amount of liquid Nitrogen. 

Limitations

• Calculation inaccuracies may arise if the dimensional measurements of samples are inaccurate. Inaccuracies also occur while maintaining temperatures in temperature scans as the inertia of the instrument used to apply oscillating stress converts mechanical energy to heat and changes the temperature of the sample. Furthermore, the data processing is largely automated, the final source of measurement uncertainty comes from computer error.
• The minimum sample size is a length of 10.0 mm (5.0 mm with clamp extenders) and the maximum sample size is 52.5 mm x 12.8 mm x 8.0 mm.

Applications

• Measuring glass transition temperature (Tg) of polymers
• Determining the viscoelasticity of materials
• Comparative failure analysis of plastics and thermosets
• Differences in elastic modulus before and after processing, post-curing or physical aging
• Detecting the phase separation of polymer blends or copolymers
• Dimensional stability of parts at operating temperature and loading
• Damping capability of polymer: dissipation of energy through internal motion; toughness
• Time-Temperature Superpositioning (TTS): study the effect of changing frequency on temperature-induced changes in polymers

Technical Specifications

• Rotating Analysis Head:
      o Vertically up (forward) and 45° in between these positions
      o Vertically down
• Temperature Range:
      o Standard furnace : -190 °C to 400 °C
      o High temperature furnace : -190 °C to 600 °C
• Scanning Rates:
      o Heating rate 0 °C to 20 °C/min* (standard furnace)
      o Cooling rate 0 °C to 40 °C/min* (standard furnace)
*at mid-range (100 °C), may not be achieved at elevated temperatures
• Frequency
      o Range : 0 to 600 Hz (depends on sample)
      o Max. number : up to 100 per experiment
      o Resolution : 0.001 Hz
• Dynamic Displacement: 0 to ±1000 µm
• Stiffness Range : 2 x 102 to 1 x 108 N/m resolution 2 N/m
• Modulus:
      o Resolution : 0.0001 Pa
      o Range : ~103 to 1016 Pa
• Tan Delta : Resolution 0.00001
• Force:
      o Range : -10 N to +10 N (range of 20 N)
      o Minimum : 0.002 N
      o Resolution : 0.002 N
• Displacement/Strain
      o Resolution : 1 nm
      o Range : ±1000 µm
• Sample Size : Maximum 52.5 mm x 12.8 mm x 8.0 mm
• Geometry Options:
      o Single Cantilever Bending
      o Dual Cantilever Bending
      o 3-Point Bending
      o Tension
      o Compression
      o Shear
• TMA Mode:
      o Measurement range : ±1000 µm
      o Geometry : Tension and compression 
      o Sensitivity : 10 nM
      o Force load min/max : 0.002 N / ±10 N
      o Sample size : up to 10 mm