Thermal Analysis of Polymers

TMA thermal expansion set up

Thermal Analysis is a powerful set of tools used to assess the response of a material to a given thermal cycle. Our full suite of thermal analysis techniques are either used to determine specific properties of a material or in support of failure analysis activities. Testing is generally conducted in accordance with the various parts of ISO 11357, ISO 11358 and ISO 11359 although other standards and non standard runs can be undertaken dependent on requirements. Please contact us to discuss your specific requirements

Differential Scanning Calorimetry (DSC)

DSC measures heat flow to a small sample of material while it is heated through a defined temperature profile. The technique is most commonly used to identify glass transition and melting points of materials. These are useful aids to polymer identification. In semi-crystalline polymers the degree of crystallinity can also be determined allowing an assessment to be made of cooling rates during processing.

The technique can also monitor cure in thermoset and rubber samples or detect signs of under-cure in finished products. DSC is also used to quantify the specific heat capacity of a material over a given temperature range (ISO 11357-4) and determine the oxidation induction time or temperature (OIT) to ISO 11357-6.

DSC can be run over the temperature range -60°C to 500°C.

Thermogravimetric Analysis (TGA)

TGA monitors the mass of a sample as it is heated. Weight losses are detected as components within a formulation are volatilised allowing quantification of the bulk composition of a polymer in terms of its organic (polymer) and inorganic content. Amongst others, the technique can quantify the moisture, polymer, glass fibre, calcium carbonate and carbon black content of a material. Due to the small samples size required (a few mg of material) an assessment can be made of the variability of these fillers through a moulding.

For most applications, runs are conducted between room temperature and 850°C in a flow of either air or nitrogen although the analysis can be run up to 1100°C.

Thermomechanical Analysis (TMA)

TMA is most commonly used for determining the coefficient of thermal expansion (CTE) of material to ISO 11359-2 or ASTM E831. The technique can also be used for determining the softening point of a material and assessing swelling and fluid absorption processes. Tests can be run from around -120°C up to 500°C in a range of atmospheres.

Dynamic Mechanical Analysis (DMT/DMTA)

DMA applies a sinusoidal deformation to a sample and allows the response of the material to be characterised in terms of its elastic and viscous properties. This allows a definition of the effects of both temperature and frequency on the storage and loss moduli of a material together with an assessment of the phase angle. Thermal sweeps can provide information regarding material transitions whilst a series of isothermal frequency sweeps can be used to construct time temperature superposition curves to derive Arrhenius activation energies. Testing is generally conducted in accordance with the various parts of ISO 6721 although other standard and non-standard procedures can also be accommodated.