Differential Scanning Calorimeter

Differential scanning calorimeter is an intelligent, compact and low cost thermal analysis instrument. QT-DSC6 Calorimeter can determine oxidation induction time of polyethylene, curing percentage of epoxy, anti-oxide of lubricant , enthalpy change of material and partial enthalpy change, glass transition temperature, extrapolated onset temperature and melting point for crystalline polymer, quality control of engineering thermoplastics, polyethylene/polypropylene blend and copolymer etc.

Differential scanning calorimeter adopts thermo analytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. Thermal Analysis is based upon the detection of changes in the heat content (enthalpy) or the specific heat of a sample with temperature

Applying this technique, the sample to be measured and the reference sample are placed inside a crucible which is then placed inside the measurement cell (furnace) of the differential scanning calorimeter system. By applying a controlled temperature program caloric changes can be characterized

Rapid analyses, easy handling and high significance for research, development and quality control are the main advantages of this analytical technique. The QT series differential scanning calorimeter mainly consists of the heating furnace, host, μV amplifier, A/D converter, μV-mW energy converter software, and the data sampling system, optional computer and printer.

The principle and structure

Differential scanning calorimeter is a technique under the program temperature control, it measures differential power between sample material and reference material with temperature as the variable. The QT-DSC6 instrument mainly consist of the heating furnace, host, µV amplifier, A/D converter, the µV-mW software energy correction, the data sampling system, computer and printer...etc. and assist the machine with two channels of gas crossing over, it get the results from the computer data processing system.

DSC signal measuring system

This system consists of a pair of thermocouples, µV amplifiers, A /D converter and the µV-mW software energy calibration etc.

Sample holder consist of a pair of thermocouple and aluminum pole etc. put the measured sample and reference sample (α-AI2O3 powder or empty) in two crucibles respectively before the experiment, the temperature of the furnace will rise, if the measured sample does not have thermal reaction, DSC curve will be displayed as a line which is called the baseline; If the measured sample has endothermic or exothermic reaction at certain temperatures (i.e. produce a difference in temperature) the difference in temperature will be amplified and input to the µV amplifier, pass by µV-mW software energy calibration and A/D converter. Finally, it will be output to the computer. The DSC curve is then drawn.

Measurement of the oxidation induction time of polyethylene

During the experiment the DSC curve is recorded and marked out to have nitrogen to cross over with oxygen at point A1. When the DSC curve changes, the tangent of the biggest inclined rate, mark the point A2 of intersection of biggest tangent and baseline extension, the time it takes to travel from point A1 to A2 is the oxidation induction time (measured min).