Glass transition temperature determination

The glass transition temperatures determined with these polyesteramide resins appeared to be strongly dependent on the type of anhydride used and of their molecular weight. Figure 10 shows the dependence of glass transition temperature on molecular weight for hyperbranched polyesteramides based on hexahydrophthalic anhydride. In general, the Tg for HHPA- and THPA-based resins were about 45-90°C, PA based resins about 70-100°C, and SA and GA about 20-40°C. 

T Glass transition temperatures determined using thermomechanical method. degr- weight loss temperature determined using TGA method (air, AT = 4.5 °Clmin). ... 

Ta = glass transition temperature determined in a dynamic mechanical test, K... 

Empirical Relationship - Empirical relationships correlating glass transition temperature of an amorphous viscoelastic material with measurement temperature and frequency, such as the William Landel Ferry equation (17) and the form of Arrhenius equation as discussed, assume an affine relationship between stress and strain, at least for small deformations. These relationships cover finite but small strains but do not include zero strain, as is the case for the static methods such as differential scanning calorimetry. However, an infinitely small strain can be assumed in order to extend these relationships to cover the glass transition temperature determined by the static methods (DSC, DTA, dilatometry). Such a correlation which uses a form of the Arrhenius equation was suggested by W. Sichina of DuPont (18). 

Melting and glass transition temperatures determined by DSC Glass transition determined by DMA... 

General conditions 0.02-0.35 mmol Ln total volume 1-60 mL Melting and glass transition temperatures determined by DSC Glass transition determined by DMA... 

Figure 3.15 Test of the mode coupling theory power law predictions for viscosity temperature dependence for a variety of molecular and ionic liquids. Tg is the glass transition temperature determined by thermal analysis at 10 K/min scanning (After Angell, 1998).

From Reference 37 with permission from Elsevier Ltd.] Glass-transition temperature determined by dynamic mechanical tests. Degree of crystalhnity in volume fraction estimated using density data. Long period evaluated by SAXS. 

Figure 13 demonstrates a relationship between molecular structure, represented by the fraction of atoms present in polymeric form in Se-S and Se-Te alloys, and the glass transition temperature determined by Myers (JO). The trend reflects the correlation made for binary alloys containing arsenic—viz, the greater the fraction of polymer the higher... 

Many crystallizable polymers can be prepared in the amorphous glassy state by rapid quenching as films. Measurements of Aglass transition temperature determined. Such results are shown for amorphous polyethylene terephthalate (PET) in Figure 13 (17). The Brillouin splittings change slope at 70°C. If both Aa>(i) and Awt can be measured, the Poisson ratio (T can be determined according to ... 

Glass transition temperature determined by middle-point method neoprene -37 C, butyl rubber -61 C, cis-polybutadiene -104 °C. 

Fig. 8 Glass transition temperature determined by DSC for TAX copolymerized with 4 eq of DBF (full symbols) and FAIR (open symbols) in function of total conversions in functions (PI 1 wt-% of TPO, Irradiation 350 nm light, P = 150 W).

Glass transition temperatures determined by DSC at a heating rate of 20 C/min. 

When this separation occurs, the glass transition temperature of the reversing heat flow is always higher than the glass transition temperature determined from the total heat flow [as seen in Rgs. 2.99 and 2.100 a detailed explanation can be found in Lacey et al. (2006)]. 

The Arrhenius plot of these polyurethanes is representative of thermoplastics with phase-separated structure (Fig. 6.25).The data for the DC conductivity show a typicd VTFH-type behavior [Eq. (6.24)] (Tuncer et al. 2005), consistent with the coupling of the conductivity mechanism with cooperative segmental motions usually observed in linear polyurethanes and several other thermoplastics. The glass transition temperatures determined by DEA (Tg diei), DSC (TgDsc), and thermally stimulated current (Tg xsc) show very good agreement. In addition, the majority of published works on polymers [e.g., see... 

Copolymer composition the mole ratio of lactic acid (LA) and glycolic acid (GA) in the copolymer Weight average molecular weight, determined by GPC Poly dispersity, determined by GPC < Glass transition temperature, determined by DSC. 

These changes being reversible, the glass-transition temperature determines whether a particular polymeric material will behave as a glass (hard and slilT plastic) or elastomer at a given temperature. In Table A are listed (he approximate Tg values for some of the polymers from which it is clear that rubbers have their Tg considerably below room temperature, whereas Tg for plastii-s is much above room temperature. Tg for fibres is also substantially higher than room temperature. 

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