Differential scanning calorimetry for measuring the crystallinity of polymers

Crystallinity, as a key parameter characterizing polymer properties, is closely related to the physical and mechanical properties of materials. Accurately measuring the crystallinity of polymer materials has important practical application value for material performance evaluation, injection molding process research and optimization, and other fields. Among various methods for testing crystallinity, differential scanning calorimetry (DSC) is widely used due to its simple operation and high accuracy of results.

Crystallinity is a parameter that measures the content of crystalline structure in partially crystalline polymer materials. It is defined as the mass fraction or volume fraction of the crystalline part in the overall material, and the calculation formula is:（mcFor crystalline quality, maFor amorphous quality).

1、 Experimental steps

1. Sample preparation: Take the central section of the granular sample and slice it evenly into the formed product.

2. Experimental equipment:DZ-DSC300C Differential Scanning Calorimeter

3. Sample size: 10-15mg (excessive amount leads to increased thermal resistance and distorted peak shape).

4. Purity control: Dry and remove water (to avoid interference of endothermic peaks in low temperature areas with baseline).

5. Heating rate: Recommended at 10 ℃/min (balancing resolution and testing efficiency); Atmosphere: Nitrogen protection, flow rate of 40-50mL/min.

6. Graph analysis:

Melting enthalpy=38.5386J/g

Recrystallization enthalpy=37.7469J/g

The total melting heat of PA66 is Δ Hf *=195J/g

Crystallinity=19.7925%

2、 Experimental conclusion

DSC technology achieves accurate determination of polymer crystallinity through standardized experimental procedures and quantitative formulas. Cold crystallization correction and composite material correction have expanded their application scope, and ASTM standards ensure the comparability of test results. Future development will focus on improving instrument accuracy, innovating combined technologies, and applying intelligent algorithms, further consolidating its core position in the field of polymer material characterization.