Mettler differential scanning calorimeter has mature applications in polymer thermal analysis, food thermal stability testing, drug composition research, and materials science fields. It can determine parameters such as glass transition temperature, eutectic point, and specific heat of materials, providing key support for material research and quality control. Support testing of large-sized samples ranging from microgram level to non-uniform, to meet different experimental needs; Modular design not only meets manual operation but also supports automated operation, simplifying complex data processing processes and improving result reliability; The calibration system ensures data consistency under different conditions and reduces human error.

Measurement steps of Mettler differential scanning calorimeter (DSC):

1. Sample preparation

-Sampling and processing: Select representative material samples, generally requiring a sample size between a few milligrams and tens of milligrams (such as fiber samples of about 10-20mg). For powdered or granular samples, appropriate compaction is required; If it is a filament or bundle fiber, it should be cut into powder or short fiber segments to avoid uneven heat conduction. Ensure that the sample is pure, dry, and free of contamination, and if necessary, perform pre-treatment (such as eliminating the heating and cooling cycles of the thermal history). Avoid direct contact with the sample by hand to prevent oil contamination.

-Weighing record: Accurately weigh the sample mass and record the data as a reference for subsequent analysis.

2. Instrument calibration

-Calibration of standard substances: Use standard substances with known melting points (such as indium and tin) to calibrate the temperature and heat flux signals of the instrument to ensure measurement accuracy.

-Atmosphere control: Turn on inert gas protection such as nitrogen (usually set at a flow rate of 50-100mL/min) to prevent oxidation reactions of the sample at high temperatures from interfering with experimental results.

-Preheat stability: After starting up, let the instrument preheat for a period of time (such as 30 minutes) to reach a stable working state.

3. Parameter settings

-Temperature program: Set the appropriate heating rate (commonly ranging from 5-20 ℃/min), temperature, and holding time according to the testing purpose. Note that a too fast heating rate may result in a higher melting point and wider peak deformation, while a too slow heating rate may prolong the measurement time. At the same time, it is necessary to ensure that the temperature range covers all possible thermal transition intervals of the sample.

-Gas atmosphere selection: Choose a suitable gas environment (such as nitrogen, air) based on the properties of the sample, and maintain a stable gas flow rate.

-Other configurations: Adjust instrument sensitivity, resolution, and other parameters to optimize data acquisition performance; Choose the appropriate sample boat or crucible type.

4. Place the sample and reference material

-Uniform distribution: Spread the processed sample evenly in an aluminum crucible, and place the blank crucible as a reference into the DSC furnace. Note that the sample size should not be too large (not exceeding 20mg), otherwise it may cause abnormal fluctuations in the curve.

-Sealing operation: Cover the crucible lid to prevent volatile substances from escaping or external impurities from entering, while avoiding sample spillage and contamination of the sensor.

5. Start testing and monitoring

-Run the program: Start the instrument and start heating according to the preset temperature program, recording in real-time the curve of the heat difference between the sample and the reference material as a function of temperature (i.e. DSC curve).

-Process observation: Pay close attention to the operating status of the instrument and changes in the data displayed by the software. If abnormal situations occur (such as temperature fluctuations, alarm prompts), the test should be immediately paused and the cause investigated.

6. Data analysis

-Characteristic temperature recognition: Using specialized software to analyze DSC curves, determine the starting temperature, peak temperature, and ending temperature of the endothermic peak. For complex systems, it may be necessary to combine multiple feature points to comprehensively determine the phase transition behavior of materials.

-Quantitative calculation: Using peak area to calculate enthalpy and other parameters, further analyze the thermodynamic properties of the sample. If necessary, conduct multiple parallel experiments to improve the reliability of the data.