DSC glass transition temperature

The empirical equation (3), derived from the Arrhenius equation, allows a rough prediction of peak loss factor temperature at dynamic frequencies from DSC glass transition temperature data. 

Keywords Fumed Silica / Polydimethylsiloxane / PDMS / Differential Scanning Calorimetry (DSC) / Glass Transition Temperature... 

PLLA/PDLLA biodegradable blends DSC, Glass transition temperature, thermal degradation of blends, TGA Miscibility of Poly-1-lactic acid (PLLA) and Poly-dl-lactic acid (PDLLA) was studied using DSC and thermal stability using TGA were studied. Chen et al. 2003... 

This value should be compared with Tgxsc = Fmax,a = H0°C (at the equivalent frequency of -10 Hz) and the DSC glass transition temperature of g,DSC = 115°C (from second heating scans at 10°C/min after cooling at 20°C/min). A rough estimate of the equivalent frequency of DSC, namely, /eq,Dsc = 2.6 X 10" Hz, Can be obtained within Donth s fluctuation model (Donth 1992) of glass transition from the relationship... 

Figure 10. Variation of the DSC glass-transition temperature of bisphenol-A polycarbonate with concentration of plasticizer. Curve A Pentaerythriol tetra nonanoate Curve B Trimellitic acid tri-decyloctyl ester Tg (1) and Tg (2) of two polymer solutions in equilibrium with each other after storage for one day at room temperature Curve C Tritolyl phosphate.

As appHed to hydrocarbon resins, dsc is mainly used for the determination of glass-transition temperatures (7p. Information can also be gained as to the physical state of a material, ie, amorphous vs crystalline. As a general rule of thumb, the T of a hydrocarbon resin is approximately 50°C below the softening point. Oxidative induction times, which are also deterrnined by dsc, are used to predict the relative oxidative stabiHty of a hydrocarbon resin. 

Fig. 23. Evolution of the glass transition temperature of polychloroprene-aromatic hydrocarbon resin blends as a function of the resin content. values were obtained from DSC experiments.

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. 

The glass transition temperatures (Tg) of both modified and unmodified PSs were determined by DSC analysis, and thermomechanic analysis was controlled by TMK. The results are given in Table 8. It is seen from Table 8 that the highest glass transition temperature (410 K) was obtained with chlorohydrinated PS and that of the lowest (370 K) with olefinic PS. The lowest glass transition temperature in the alkenylated PS caused to elasticity properties on polybutadien and polyisopren fragments. 

DSC helps in determining the glass-transition temperature, vulcanization, and oxidative stability. TG mainly is applied for the quantitative determination of major components of a polymer sample. TMA or DLTMA (dynamic load thermomechanical analysis) measures the elastic properties viz. modulus. 

A report130 of DSC measurements on polybenzimidazole fibers describes important differences for the glass transition temperature depending on die mechanical treatment of the fiber. An as-spun fiber exhibits a Tg at 387°C instead of 401°C for a drawn fiber free to shrink or 435°C for a drawn fiber widi fixed length. 

The greatest use for DSC has turned out to be for characterization of organic polymers. It has been found that most polymers are amorphous and have a characteristic Tg, i.e.- a "glass" transition temperature which leads to a... 

Figure 10.7 The phase diagram (a) and the glass transition temperatures (b) of a PSC/PVME mixture obtained, respectively, by light scattering and differential scanning calorimetry (DSC). Irradiation experiments were performed in the miscible region at 127 C indicated by (X) in the figure of trans-cinnamic acid-labeled polystyrene/poly(vinyl methyl ether) blends.

The increase in the length of the side chain results normally in an internal plasticization effect caused by a lower polarity of the main chain and an increase in the configurational entropy. Both effects result in a lower activation energy of segmental motion and consequently a lower glass transition temperature. The modification of PPO with myristoyl chloride offers the best example. No side chain crystallization was detected by DSC for these polymers. 

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