Thermal Analysis Service
Thermal analysis measures physical or chemical changes in a material as a function of temperature. Two common complimentary techniques of thermal analysis offered by the Thermal Analysis Service are Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). DSC provides information about physical and chemical changes that involve endothermic and exothermic processes, or changes in heat capacity, and is useful in materials testing (e.g. foods, plastics, pharmaceuticals etc.). TGA is a technique for measuring changes in mass as function of temperature and is primarily used to determine the composition of substances.
The Thermal Analysis Service in the Department of Molecular Sciences provides DSC and TGA analysis services for both the research needs of the Faculty of Science as well as for the wider research community within Australia.
So, how can we help you?
Below are some typical questions commonly asked about the Thermal Analysis Service. If one of the following fails to answer your question, please feel free to contact us:
- How do I submit my sample for Thermal Analysis?
- How much will it cost me to get Thermal Analysis
- For what type of samples can I get Thermal Analysis?
- What sort of Thermal Analysers does the service have?
- How does Thermal Analysis work?
- To whom do I direct questions about the Thermal Analysis Service?
Principles of Thermal Analysis
DSC - Differential scanning calorimetry measures heat flow to or from a sample as a function of temperature and time. A small portion of a sample is placed in an aluminium pan and heated and/or cooled in a controlled manner. A reference material (usually an empty aluminium pan) simultaneously undergoes the same programmed time/temperature routine. The heat flow (watts) and temperature of the sample are monitored in comparison to the reference material. The analysis is usually performed in an inert gas atmosphere, such as nitrogen. The amount of energy absorbed (endotherm) or evolved (exotherm) as the sample undergoes physical or chemical changes (e.g. melting, boiling, crystallisation, curing) is measured in watts as a function of the temperature change. Any material reactions involving changes in heat capacity (e.g. glass transition) are also measurable.
DSC experiments provide a graph of energy flow vs. temperature for thermal transitions in materials. The transitions that can be measured include melting points, boiling points, glass transition temperatures, heats of reaction, thermal and oxidative stability, and kinetics and energetics of some cure reactions.
TGA - Thermogravimetric analysis continuously measures the weight of a sample as a function of temperature and time. The sample is placed in a small pan connected to a microbalance and heated in a controlled manner and/or held isothermally for a specified time. The atmosphere around the sample may consist of an inert gas, such as nitrogen, or a reactive gas, such as air or oxygen. The heating program may start in an inert atmosphere and then be switched to air at a certain point to complete the analysis. Weight changes observed at specific temperatures correlate to volatilization of sample components, decomposition, oxidation/reduction reactions, or other reactions or changes.
TGA provides a graph of mass loss vs. temperature. This analytical technique is widely used in polymer science, inorganic chemistry, fuel science, and geology to measure the loss of volatile components or thermal stability of a sample. The experiments are usually run with a temperature ramp of 10 or 20 deg/min and can be carried out in inert atmospheres, such as nitrogen, to study thermal stability or volatility, or in oxidizing atmospheres to study oxidative decomposition. The mass losses can be characteristic of a material and, where the losses are in discrete steps, the TGA experiment can offer quantitative data on the course of a decomposition. The TGA also can be run in an isothermal mode, where the rate of weight loss at a fixed temperature is measured. This type of experiment can be used to predict loss rates of volatiles or decomposition rates for materials.
The Thermal Analysis Service offers DSC analysis using a TA Instruments DSC2010, which is capable of temperatures from -65 to 725°C. The standard sample container is a disposable aluminium pan and cap combination and is limited to an upper temperature of 600°C, but special materials such as copper, gold, platinum, or graphite can be used up to 725°C. These special materials are only available on request and at additional cost. The analysis is normally run in a flowing nitrogen atmosphere except for determinations of oxidative stability where air or oxygen is used.
Thermogravimetric analysis is provided using a TA Instruments TGA2050. The upper temperature limit is 1000 °C, but with the exception of some mineral specimens, most experiments are complete before 800 °C. We currently offer TGA analyses in nitrogen or air. Other non-explosive, non-corrosive, and non-toxic atmospheres may be provided at additional cost.
Applications of DSC
DSC data, either used alone or in conjunction with sequence, stability and structural data, can provide information on the Effects of protein mutagenesis and engineering, Effects of buffer, pH, salt, additives, Effects of post-translational modification, Reversibility of unfolding (by changes in ΔH), Presence of multiple unfolding domains, Stability contributions of individual domains, Formation of protein complexes, Effects of lipid, nucleic acid, or other biopolymer on protein stability.
Glass transition temperatures (Tg), crystalline melting temperature (Tm), degree of crystallinity and heat of fusion, oxidative stability, heats and kinetics of polymerization reactions.
Determination of cure in epoxy prepegs, solder mask cure analysis, cure kinetics of thermoset encapsulants.
INORGANIC MATERIALS & MINERALS
Melting points, energy and temperatures of dehydration or other small molecule loss, secondary transitions.
Applications of TGA
Weight loss vs. temperature, loss of water from nylon and other hygroscopic polymers. Determination of fillers, reinforcements, and pigments. Analysis of rubber compositions. Also, volatilization of additives, kinetics of decomposition, and oxidative stability studies.
Resin content of printed circuit boards. Volatilization curves for fluxes. Thermal decomposition of wire insulation and components.
Water and volatiles content of solid dosage forms.
INORGANIC MATERIALS AND MINERALS
Determination of temperatures of dehydration, elimination, and decomposition. Quantification of volatiles loss.
System decomposition curves. Filler and reinforcement analysis. Oxidative stability. Lifetime prediction.
Submitting Your Samples
Thermal Analysis Submission Form
Submission forms can be obtained from Thermal Analysis facility in the Department of Molecular Sciences or you can download a form here.
A sample submission form must accompany each sample submitted. The sample label give on the submission form must be the same as the label on sample vial.
For both DSC and TGA, typically 10 mg will be enough material, however if possible more sample (25-50 mg) should be provided for greater precision and to facilitate handling. In cases where you have very little sample available, it is possible to do some types of DSC and TGA analyses with as little as 1 mg of sample.
The weight required is the amount that must be removed from the sample vial - not the amount put into the sample vial. We will happily return any unused sample to you.
Cost of Service
Experienced and committed Analytical chemists in the Chemical Analysis Facility will do their best to bring you the accuracy you need in thermal analysis with carefully documented results. Turnaround times average less than three working days for routine single samples. An express service is available for results within hours with an advance appointment.
Cost of the service will depend on application, type of pans used (copper, gold, aluminium) etc. but as a general cost guideline, we charge either $70+GST per sample for runs less than 2 hours, or $40+GST/hour for runs longer than 2 hours. There is also a one-off "setup" fee (to cover calibration etc. for your run conditions) of $35 regardless of the number or type of sample.
The thermal analysis service is under the direction of Dr Christopher McRae. The service is managed by an experienced technician.
Please contact us for further information:
Thermal Analysis Service
c/o Dr Christopher McRae
Department of Molecular Sciences
NSW 2109 Australia
Tel: +61 (2) 9850 8288