Differential scanning calorimetry example results

Differential scanning calorimetry (DSC) is fast, sensitive, simple, and only needs a small amount of a sample, therefore it is widely used to analyze the system. For example, a polyester-based TPU, 892024TPU, made in our lab, was blended with a commercial PVC resin in different ratios. The glass transition temperature (Tg) values of these systems were determined by DSC and the results are shown in Table 1. 

We use differential scanning calorimetry - which we invariably shorten to DSC - to analyze the thermal properties of polymer samples as a function of temperature. We encapsulate a small sample of polymer, typically weighing a few milligrams, in an aluminum pan that we place on top of a small heater within an insulated cell. We place an empty sample pan atop the heater of an identical reference cell. The temperature of the two cells is ramped at a precise rate and the difference in heat required to maintain the two cells at the same temperature is recorded. A computer provides the results as a thermogram, in which heat flow is plotted as a function of temperature, a schematic example of which is shown in Fig. 7.13. 

The kinetic results of the differential scanning calorimetry studies on the monomers in Table 3 are presented in Tables 4 and 5. The reaction order n with the exception of example 78a in Table 3 was approximately unity for all of the... 

The DHA-containing phospholipids exhibit very low phase transition temperatures. For example, 18 0,22 6 PC has its at about-9°C (Stillwell etal., 2000), whereas 22 6,22 6 PC s transition is at -68.4°C (Kariel et al., 1991) and the transition enthalpy H for homo acid is extremely low ( H = 0.5 kcal/mol) (Kariel et al., 1991). The low T, s are the result of packing restrictions resulting from steric effects caused by DHA s multiple rigid double bonds. The restrictions result in reductions in intermolecular and intramolecular van der Waal s interactions. The broad, low H transitions are consistent with the notion that interaction between saturated sn-1 chains stabilize the gel state in hetero acids (Kariel et al., 1991). Furthermore, differential scanning calorimetry (DSC) isothenns are often multi-component, suggesting microclustering and domain formation (Niebylski Salem, 1994). 

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