Submersion Dynamic Mechanical Analyzer

What is the Submersion Dynamic Mechanical Analyzer?

A submersion dynamic mechanical analyzer measures viscoelastic properties of a specimen immersed in liquid or buffer, which is essential for hydrogels, biological tissue and materials that must stay hydrated. It also allows solvent uptake and swelling effects to be followed.

Overview

The specimen holder sits in a temperature-controlled fluid bath or a small cup filled with medium, so modulus and damping are measured in the hydrated or swollen state that matches service conditions. Tension and compression modes are most common; hydrogels and soft tissue are run in compression or tension with very low force and pre-tension control, while coupons of coatings or membranes are run in tension. Temperature control of the bath, typically 5 to 80 degrees Celsius, plus the ability to change the medium during a run, allows swelling kinetics and plasticisation by solvents to be studied. Because fluid adds mass and damping to the fixture, the instrument must be able to correct for buoyancy and for the added stiffness of the bath mounting, and calibration in air may not apply directly. Force resolution of about 1 millinewton is required for very soft biological specimens.

How does it work?

The instrument clamps the specimen in a chosen geometry and applies a sinusoidal stress or strain while measuring the response. Because a viscoelastic material does not respond instantaneously, the strain lags the stress by a phase angle, and the ratio of amplitudes together with that phase angle yields the complex modulus. Its real part is the storage modulus, describing elastic energy stored per cycle; the imaginary part is the loss modulus, describing energy dissipated as heat; and their ratio is the damping factor, tan delta, whose peak defines the glass transition temperature. Measurements are made in single or dual cantilever, three-point bending, tension, compression or shear mode, with the geometry chosen to suit the sample stiffness. Temperature ramps of 0.5 to 5 degrees Celsius per minute, frequency sweeps from 0.01 to 100 hertz, and single or multi-frequency operation allow activation energies, cure profiles and master curves to be derived.

What are the key features?

• Fluid bath or medium cup for immersed specimen measurement
• Bath temperature control from 5 to 80 °C
• Very low force resolution for hydrogels and tissue
• Medium exchange during a run for swelling studies
• Buoyancy and fixture damping correction routines
• Compatible with tension, compression and bending clamps

What are the technical specifications?

A typical submersion dynamic mechanical analyzer configuration offers force range of 0.001–20 N, force resolution of 0.001 N, frequency range of 0.01–50 Hz, bath temperature range of 5–80 °C, medium volume of 20–200 mL and clamping modes of Tension, compression, 3-point bending. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Submersion Dynamic Mechanical Analyzer is used in hydrogel mechanics and swelling, biological tissue and scaffold testing, coating performance in immersion service, membrane behaviour in electrolyte and solvent uptake in polymer coupons. Across the wider DMA class, laboratories also deploy it for composite and laminate viscoelastic characterisation, elastomer and rubber compound testing and thermoset cure monitoring.

Which standards and certifications apply?

Relevant standards and methods include ASTM D4065, ASTM D5023, ASTM D5024, ASTM D5026, ASTM E1640 and ISO 6721-1. Certification candidates for this model are CE, IEC 61010-1 safety and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Specimen geometry must be measured accurately, because modulus depends on the cube of thickness in bending and on cross-sectional area in tension, so a dimensional error is amplified. Clamp the specimen without pre-stress or slippage, verify that the measured stiffness lies in the instrument's reliable range, and check linearity by repeating at a second amplitude. Calibrate the instrument with certified stiffness standards or reference materials and record the geometry, amplitude, frequency and atmosphere for each run. Beware of thermal lag at higher heating rates, which shifts transition temperatures upward, and of clamp expansion that can add apparent strain. For thermosets, run the cure in a multi-frequency mode so gelation and vitrification can be separated. Purge gas is required for measurements above room temperature to avoid oxidation, particularly in elastomers.

How do I select the right Submersion Dynamic Mechanical Analyzer?

Choose the submersion configuration when the material is normally hydrated or exposed to liquid and dry measurement would change its properties, as with hydrogels, tissue or membranes. For dry structural materials, a standard instrument is adequate. In an RFQ, specify medium, temperature range, force resolution, mode and any medium-exchange requirement.

How does it compare with other DMA variants?

Choose the clamping geometry before anything else, because it determines the specimen dimensions and the usable stiffness range: three-point bending suits stiff bars, single and dual cantilever suit medium-modulus plastics and composites, tension suits films and fibres, and compression or shear suit soft gels and foams. Then match the force range to the material: stiffer samples and composites need higher force and a rigid frame, while thin films and gels need very low force with high displacement resolution. Check the temperature range and the cooling system, since liquid nitrogen is needed for sub-ambient glass transitions. Frequency range, multi-frequency capability and the software for master curve generation matter for research, while a simple temperature sweep with specification limits is enough for quality control. For hydrogels, biological samples or humid environments, ensure the instrument can accept a submersion or humidity accessory.