Low-Temperature Thermomechanical Analyzer

What is the Low-Temperature Thermomechanical Analyzer?

A low-temperature thermomechanical analyzer cools with liquid nitrogen or a mechanical cooler to minus 150 degrees Celsius or below, measuring contraction, glass transitions and low-temperature dimensional stability of polymers, elastomers, adhesives and cryogenic materials.

Overview

Sub-ambient measurement requires a nitrogen-cooled or mechanically refrigerated furnace, a dry purge to prevent frost and a probe material with low and known expansion, such as fused silica. The displacement channel resolves a few nanometres, which allows contraction of low-expansion materials to be followed from room temperature down to minus 100 degrees Celsius or lower. Typical specifications are a range from minus 150 to 400 degrees Celsius, heating and cooling rates from 0.5 to 20 degrees Celsius per minute, and temperature accuracy of about 1 degree Celsius after calibration with indium and water. Applications include glass transitions of elastomers and adhesives measured in penetration mode, thermal contraction of composite laminates for cryogenic tanks, dimensional stability of optical mounts, and shrinkage of moulded parts on cooling. Matching specimen and probe expansion behaviour is important because the correction term grows as the temperature falls.

How does it work?

A probe rests on the specimen and is connected to a linear variable differential transformer, which converts displacement into an electrical signal with resolution near one nanometre. A furnace programs the temperature while a defined static or oscillating load holds the probe in contact. Depending on the probe and holder fitted, the instrument measures expansion, compression, penetration, tension or three-point bending, and the same displacement channel serves all modes. Coefficient of thermal expansion is calculated from the slope of the expansion curve over a chosen temperature interval, and softening or glass transition temperatures are read from the onset of probe penetration. Calibration uses reference materials of known expansion such as fused silica or aluminium, plus melting point standards for the temperature channel. Probe material, load and contact geometry must be recorded because they influence the measured displacement, and sample preparation must give parallel, flat faces.

What are the key features?

• Liquid nitrogen or mechanical cooling to −150 °C
• Fused silica probe for low and well-known expansion
• Penetration and tension modes for elastomers and films
• Dry purge and insulated chamber to prevent frost
• Calibration with indium and water transition standards
• Programmed cooling for contraction and shrinkage studies

What are the technical specifications?

A typical low-temperature thermomechanical analyzer configuration offers temperature range of −150–400 °C, cooling method of Liquid nitrogen or mechanical cooler, heating and cooling rate of 0.5–20 °C/min, displacement resolution of 5–20 nm, temperature accuracy of ±1 °C and load range of 0.001–2 N. 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 Low-Temperature Thermomechanical Analyzer is used in cryogenic composite laminate contraction, elastomer and adhesive glass transitions, optical and metrology mount stability, moulded part shrinkage on cooling and cold-chain packaging materials. Across the wider TMA class, laboratories also deploy it for coefficient of thermal expansion of metals and ceramics, polymer softening and glass transition and electronic substrate and packaging materials.

Which standards and certifications apply?

Relevant standards and methods include ASTM E831, ASTM E1363, ASTM D696, ISO 11359-1, ISO 11359-2 and IEC 61010-1. 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.

Prepare specimens with parallel, flat and smooth faces, and record the original length precisely, because expansion results are normalized to it. Keep the load low enough to avoid deforming the sample, and allow the probe to settle at the starting temperature before beginning the ramp. Verify the expansion channel with a certified reference such as fused silica or aluminium and check the temperature channel with melting point standards. Beware of systematic artefacts: probe and holder expansion must be subtracted, and soft samples can show apparent shrinkage from creep under load. Keep the furnace and probe clean, replace worn probes, and use the correct purge gas to avoid oxidation or reaction with the specimen. Record mode, load, probe material, gas and calibration data with every curve.

How do I select the right Low-Temperature Thermomechanical Analyzer?

Choose the low-temperature configuration when dimensional behaviour below room temperature matters, as in cryogenic, cold-chain or optical applications. For ambient to moderate temperatures a standard instrument is adequate. In an RFQ, specify the minimum temperature, cooling method, probe material, mode and available coolant supply.

How does it compare with other TMA variants?

Decide the measurement mode first, because it dictates the probe and holder: expansion requires a flat-ended probe and often a horizontal or vertical dilatometer configuration, penetration and compression suit polymers and soft materials, tension suits films and fibres, and three-point bending suits rigid bars. Then set the temperature range, since it determines whether the furnace uses quartz, alumina or graphite and whether cooling uses liquid nitrogen or mechanical refrigeration. Displacement resolution matters most for thin films and low-expansion ceramics, where nanometre sensitivity is needed. Load range and control quality decide whether soft, low-modulus samples can be measured without deformation caused by the probe itself. Check the atmosphere and vacuum options, calibration standards supplied, sample preparation tooling and whether the instrument can be upgraded with a humidity generator or an automatic sample changer.