DSC experimental results

Based on the TG and DSC experimental results it can be concluded that the excipients, that is, magnesium stearate, magnesium trisilicate, and Si02, have no substantial influences on the thermal stabihty of ascorbic acid. This result shows that the three compounds can be used (at least from a thermal point of view) as excipients, with no restrictions, for ascorbic acid tablet formulations, since they will not provoke or accelerate the thermal degradation of ascorbic acid. However, by comparison of Tables 3.5 and 3.7, it is evident that the temperature of the... 

Table 2.2 DSC experimental results of DSC with scanning rate of 10°C/min...

We have discussed this problem in previous publications [8,9,11] and more systematically in our review [2] in an attempt to show that reliable information on water-surfactant interactions can be obtained from SZT-DSC experimental results. The gist of our argument is that any (measurable) amount of free water formed in a microemulsion sample will necessarily be detected as a melting peak at about 0°C in the endothermic mode of SZT-DSC. Thus, free water cannot be formed in the system and concurrently not revealed by this peak The same conclusion should, of course, also be valid if boimd (or interphasal) water formed at ambient temperature was detached... 

Table 2 is a summary of the experimental results from all methods This table gives the ratio of each concentration obtained from the DSC, the PFC, the TF, and the FP to that from the ACC, and the ratio of each value from the ERM and the PRM to that from the PFC. The results in Table 2 show that good agreement was obtained between the DSC and the ACC. However, the ratio of the results from the PFC to that of the ACC was 1.15 0.33. Furtheremore, the value obtained from the TF was usually smaller than that from the ACC, and the mean value was 0.68 0.18. The value obtained from the FP was smaller than that obtained from the ACC. This results is because radon and its daughters are usually at non-equilibrium state in the atmosphere. 

The cure kinetics were determined using differential scanning calorimetry (DSC). The following second-order rate equation could adjust the experimental results obtained for formulations containing 5-15 parts of hexa ... 

From the experimental results (Fakirov, 1999) and taking into account the experimental conditions used for the coreactive blending (275-290 °C, a treatment time of 45 min, the presence of a transesterification catalyst), one has to assume the occurrence of intensive chemical interactions. It is also to be expected that these reactions will lead not only to the formation of copolymers, but will also result in a more or less complete randomization of the sequential order of the repeating units (eq. (5.8)). If this is the case, the initially two-component blends should be converted into one-component ones. The latter represent one-phase systems (copolymeric material) whenever randomization (i.e. amorphization) takes place. That this occurs can be concluded from the DSC curves shown in Fig. 5.6. In contrast to the homopolymer PET the blends do not crystallize and they exhibit only one glass transition temperature. 

Fig. 15 Theoretical phase diagram of PF2/6 as a function of M for T > Tg and the compilation of the corresponding experimental results. M defines low (LMW, M < M ) and Mn high (HMW, Mn > M ) regimes. The solid line shows the theoretical Nem-Hex phase transition. The Hex-Nem transitions based on DSC and XRD measurements are marked by solid triangles and open circles, respectively. The grid-lines correspond to the Mn of experimentally studied materials. The vertical bar at 90-130 °C for Mn = 8 kg/mol shows the position of occasionally seen Hex traces. Reprinted with permission from [24]. (2005) by the American Physical Society...

A possible model of the crystalline structure which can explain the experimental results obtained by X-ray, solid-state NMR and DSC is the one based on the assumption that both the 3HB and 3HV units are simultaneously cocrystallized into the same crystalline lattice [48]. Such a so-called isomorphism is expected to occur because the chemical structure of both of the monomeric units are not so significantly different from each other. 

A P(3HB-co-4HB) sample containing 82mol% 4HB unit was found to show a sharp DSC melting endotherm at about 45°C [64, 65], which is close to the melting point (54°C) observed for the P(4HB) homopolymer [66]. P(3HB-co-4HB) samples with 4HB contents over the range 85-100 mol% are found to have the non-P(3HB) type of crystalline lattice with a degree of crystallinity of 30-40% [65]. These experimental results suggest that the 3HB and 4HB units cannot cocrystallize in the same lattice. 

Lewandowicz et al. (1997) conducted experiments to study the effect of microwave processing on the physicochemical properties of cereal starches. They used corn, wheat, and waxy corn at an intermediate moisture content of 30%. Brabender rheological method, light microscopy, x-ray diffractometry (XRD), and differential scanning calorimetry (DSC) methods were used to test different properties of starches, both before and after microwave processing. The experimental results are shown in Figures 3.2 and 3.3. Corn and wheat had pronounced changes in their molecular structure compared to waxy corn. 

The experimental results on protein unfolding thermodynamics have been extensively reviewed [35,36,41,50,51]. We have already considered the reversibility and the two-state assumptions let us now examine briefly the thermodynamical functions as they are determined by the application of DSC. 

Solid-state NMR spectroscopy should certainly not be used in isolation. For example, the assignment of solid-state spectra is aided by the existence of solution-state NMR spectra, while if dynamic processes are to be investigated, it is very useful if differential scanning calorometry (DSC) curves can be first obtained, so that the temperatures at which phase transitions occur are known in advance. In addition, the advances in computing power as well as the development of methodology means that the use of quantum chemical calculations of NMR parameters in the interpretation of experimental results will become ever more popular. 

TG, DTA and DSC curves of the cadmium peroxotitanate complex Cd2[Ti2(02)20(0H)6] H20 were recorded and used to determine the isothermal conditions suitable for obtaining the intermediate samples corresponding to the phases observed during the thermal decomposition. The experimental results were used to propose a mechanism of thermal decomposition of the investigated compound to CdTiOa. The aim of this study has been to determine the optimum conditions for obtaining CdTiOa with well-defined crystallinity [133],... 

In this article, we have discussed two different topics related to the glass transition of thin polymer Aims. As the first topic, we have shown the experimental results of the glass transition and a-dynamics of stacked thin polymer films measured by DSC and DRS. It has been revealed that interfacial interaction can play a crucial role in determining how Tg deviates from the value of the bulk system if the thickness decreases from that of the bulk. Furthermore, annealing above Tg can induce a change in the interfacial interactirMi between thin layers, and this can control the fragility and the non-Arrhenius behavior. 

In addition, the model s predicted miscibility window compares favorably with our experimental results derived from DSC analyses. The reason is that the interassociation equilibrium constant between (DAT) and thymine (T) is ca. 890 (i.e., it is stronger than the interassociation equilibrium constant... 

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