Differential scanning calorimetry data interpretation

When a number of polymorphs are identified in step one they should be characterized by Differential Scanning Calorimetry (DSC) to obtain AHm and Tm data. This information confirms their relative stabilities with respect to temperature. If DSC data cannot be obtained then slurry experiments should be performed. It is always good practice to confirm the relative stability with sluny experiments because DSC traces can be difficult to interpret correctly, and can mask subtle effects. 

Comparson of the transitions observed by differential scanning calorimetry in membranes of M. laidlawii and in water dispersions of the lipids from the membranes support the concept that most of the lipids exist as a smectic mesophase in the membranes. The evidence for a bilayer structure is straightforward in this case. Lipid transition temperatures are a function of fatty acid composition and correlate well with biological properties. The calorimeter possesses advantages over high resolution NMR for M. laidlawii, and perhaps in many other systems, because the data can be interpreted less ambiguously. In M. laidlawii membranes the bilayer appears to be compatible with the same physical properties observed in other membranes—a red-shifted ORD, lack of ft structure in the infrared, reversible dissociation by detergents, and poorly... 

Dynamic mechanical property (DMP) measurements are used to evaluate the suitability of a polymer for a particular use in sound and vibration damping. Since the dynamic mechanical properties of a polyurethane are known to be affected by polymer morphology (4), it is important to establish the crystallization and melting behavior as well as the glass transition temperature of each polymer. Differential scanning calorimetry (DSC) was used to determine these properties and the data used to interpret the dynamic mechanical property results. 

A big advantage of differential scanning calorimetry over the traditional stability test is the speed of determination. However, like all methods, differential scanning calorimetry has its own limitations. It is not applicable if the test materials exhibit properties that make data interpretation difficult, such as eutectic formation, coincident melting, and dissolution of one component in the melt of the other. It is not advisable to rely on differential scanning calorimetry alone to determine incompatibility. Chrzanowski et al. (30) reported that differential scanning calorimetry... 

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