Differential Scanning Calorimetry DSC Analysis

Figure 9. Differential scanning calorimetry (DSC) analysis of PTBS-b-PMMA (10 wt.% acid).

When one polymorph can be thermally converted to another, differential scanning calorimetry (DSC) analysis cannot be used to deduce the heat of transition between the two forms, and so solution calorimetry represents an alternative methodology. This situation was encountered when evaluating the polymorphs of losartan [140], Enthalpies of transition were obtained in water (A(A//sol) = 1.723 kcal/mol) and in A A-dimethylformarnide (A(A//S0 ) = 1.757 kcal/mol), with the equivalence in results demonstrating the quality of the results. Although enthalpy does not indicate stability, the authors deduced from solution calorimetry that form I was more stable than form II at ambient temperature. 

Rytter et al. reported polymerizations with the dual precatalyst system 14/15 in presence of MAO [30]. Under ethylene-hexene copolymerization conditions, 14/MAO produced a polymer with 0.7 mol% hexene, while the 15/MAO gave a copolymer with ca. 5 mol% hexene. In the mixed catalyst system, the activity and comonomer incorporation were approximate averages of what would be expected for the two catalysts. Using crystallization analysis fractionation (CRYSTAF) and differential scanning calorimetry (DSC) analysis, it was concluded in a later paper by Rytter that the material was a blend containing no block copolymer [31],... 

The two most popular methods of calculation of energy of activation will be presented in this chapter. First, the Kissinger method [165] is based on differential scanning calorimetry (DSC) analysis of decomposition or formation processes and related to these reactions endo- or exothermic peak positions are connected with heating rate. The second method is based on Arrhenius equation and determination of formation or decomposition rate from kinetic curves obtained at various temperatures. The critical point in this method is a selection of correct model to estimate the rate of reaction. 

The differential scanning calorimetry (DSC) analysis of atorvastatin calcium, Form-I, was performed using a Mettler Toledo 821 DSC system, operating with Star software (version Solaris 2.5.1), and is shown in Fig. 1.59. 

From a technological point of view, the dynamic crystallization of composites is of a great interest, because most of processing routes take place under these conditions. Generally, the crystallization and melting behaviour of polymer/CNT nanocomposites is analyzed by differential scanning calorimetry (DSC) analysis the transition temperatures are taken as the peak maximum or minimum in the... 

It is well known that most of the diazoniun compounds are thermally unstable and easily decompose in an aqueous solution. Iherefore, the thermal stability of diazoniun salts in an aqueous solution and in a film was evaluated by a kinetic analysis of the thermal decomposition and differential scanning calorimetry (DSC) analysis. 

Differential scanning calorimetry (DSC) analysis of (R)-54 shows a large irreversible exothermic peak at 202 C AH = -95.5 J/g). This indicates that the polymer undergoes chemical decomposition. The main chain of (R)-54 is made of acyclic ene-diyne fragments that are known to undergo Bergman cyclization (Scheme 28) to generate 1,4-dehydroaromatic diradicals at about 200 C 156,57]. The irreversible reaction of (R)-S4 at 202°C observed by DSC analysis may be caused by such an... 

The Tin values of homo-polyethylene and homo-PMCP (67.6% trans rings) produced using catalyst 7 were 138.0 and 76.7 °C, respectively. The poly(ethylene-co-l,5-HD)s produced by the same catalysts showed multiple melt transitions. As an example, a copolymer containing 16.7 mol% of 1,5-HD units in the main chain showed TmS at 88.6 and 116.4 C, and a copolymer containing 39.6 mol% of 1,5-HD units in the main chain showed TniS at 73.8 and 96.9 C. The crystallinity of the copolymers, as measured by XRD analysis, decreased monotonously as the content of 1,5-HD units in the main chain increased. Poly(propylene-co-l,5-HD)s produced by 7 lost their crystallinity, as evidenced by both XRD and differential scanning calorimetry (DSC) analysis, as the content of 1,5-HD units in the main chain was increased. Thus, when the content of enchained 1,5-HD units reached 6.7%, the copolymer showed no Tm and no characteristic XRD peaks. 

Figure 9.1 shows a typical differential scanning calorimetry (DSC) analysis of thermal behavior of two amorphous PLAs, that is, a PDLLA (M = 70 kDa) sample that is intrinsically amorphous and PLLA M = 200 kDa) that was quenched to the amorphous state by fast cooling at — 100°C/min after melting. In both cases, the Tg is evident and is located at about 65°C. 

In conclusion, a starchy material is converted into thermoplastic starch (TPS) by melting in closed devices such as heated extruders or other closed devices capable of maintaining temperature, pressure and shear conditions. Starch that has undergone a thermoplastic transformation does not show the typical melting peaks of native starch at specific water content, under differential scanning calorimetry (DSC) analysis in sealed vials, and can be defined as thermoplastic starch. 

Peripheral modification of the receptor molecules may allow the existence of stacking structures in soft materials such as thermotropic liquid crystals. Differential scanning calorimetry (DSC) analysis of the octane xerogel of Ic Cl -TATA+ suggested the formation of a mesophase as observed in the phase transitions at 88 and 42°C upon first cooling from the isotropic liquid state (Iso) and at 44 and 96°C upon second heating. 

Automotive industry waste provided another idea for a study [10]. Recycled plastics from bumpers are being applied in several areas, even as new bumpers [11, 12]. Thermal analysis was applied to the material used in discarded car bumpers, which came from standard grade automobiles of different brands. The recycled polymer composition was a polymeric blend of PP, ethylene-propylene-diene monomer (EPDM) and high-density polyethylene (HOPE). Differential scanning calorimetry (DSC) analysis (Figure 2.5) confirmed the presence of PP, and indicated HDPE and EPDM as ingredients in the formulation of car bumpers. 

The Differential Scanning Calorimetry (DSC) analysis of a binary mixture of Uthium/polyvinylidene fluoride (PVDF), (CH2F2) , in air reveals two endotherms at both 175 and 180 °C indicative of fusion of both PVDF and Li and the onset of an extended exothermic reaction at 355 °C [6] with significant subsequent heat release. 

In this chapter, the basics of differential scanning calorimetry (DSC) analysis and its correlation to polymer morphology for semicrystalline polymeric materials are presented. After a brief review of fundamental concepts, the utility of the technique is illustrated by a series of practical applications. 

The thermal properties of the SCL-MCL PHA copolymer isolated from recombinant E. coli harboring the pTrcFabH(F87T) and pBBRGEC plasmids were determined by differential scanning calorimetry (DSC) analysis and compared with the thermal properties of P(3HB) homopolymer. All data were determined from the endotherm profiles (Figure 4). 

Differential scanning calorimetry (DSC) analysis was carried out under nitrogen atmosphere. The HP-LCP powder was heated from 25 to 380 °C at a heating rate of 10 K/min. Figure 2.1 depicts the first heating curve. The endothermal peak was... 

Kissinger relationship, the most extensively used method in kinetic studies since 1957 [13], was in use to determine the energy of activation and the order of reaction, from plots of the logarithms of the heating rate against the temperature inverse at the maximum reaction rate in isothermal conditions. This method is usually based on the Differential Scanning Calorimetry (DSC) analysis of formation or decomposition processes and in relation to these processes the endothermic and exothermic peak positions are related to the heating rate. 

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