Thermal Analysis Application Brief Determination of Polymer Crystallinity by DSC

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Summary
Perhaps no fundamental property affects the physical properties of a polymer in so general a way as the degree of crystallinity. Differential scanning calorimetry (DSC) provides a rapid method for determining polymer crystallinity based on the heat required to melt the polymer.

Introduction
An understanding of the degree of crystallinity for a polymer is important since crystallinity affects physical properties such as storage modulus, permeability, density, and melting point. While most of these manifestations of crystallinity can be measured, a direct measure of degree of crystallinity provides a fundamental property from which these other physical properties can be predicted. Differential scanning calorimetry (DSC) is a technique which measures heat flow into or out of a material as a function of time or temperature. Polymer crystallinity can be determined with DSC by quantifying the heat associated with melting (fusion) of the polymer. This heat is reported as % crystallinity by ratioing against the heat of fusion for a 100% crystalline sample of the same material, or more commonly by ratioing against a polymer of known crystallinity to obtain relative values.