Meaning
Thermoanalytical technique that measures the heat flow associated with transitions in a material as a function of temperature. The method provides data on the thermal properties of polymers by comparing a sample to an inert reference during a controlled heating or cooling cycle.
Thermal Transition
Differential heating between the sample and the reference allows for the detection of endothermic and exothermic events. Using a controlled temperature programme, dsc identifies the thermal history and composition of a polymer sample. This information helps moulders determine the correct processing temperatures for a specific batch.
Crystallinity Calculation
Integration of the area under the melting peak allows for the calculation of the crystallinity of a semi-crystalline resin. This information is necessary for predicting the shrinkage and mechanical strength of a part after it cools in the mould. The test also identifies the glass transition temperature, which determines the point where a rigid polymer becomes flexible or leathery.
Quality Verification
Comparison of a regrind sample against a virgin material datasheet reveals the presence of contaminants or blended resins. If a batch of polypropylene shows a secondary melting peak at a lower temperature, it indicates the presence of polyethylene. Verification of the enthalpy of fusion provides a reliable measure of the degree of crystallinity in semi-crystalline resins.
