Fraction of amorphous phase

Heat capacity measurements at the glass transition temperature, Tg, are based on the same differential concept. The weight fraction of amorphous phase is calculated as the ratio of changes of heat capacity of the semi-crystalline sample ACp(S) over the change in heat capacity of the melt (ACp(m)) at the glass transition. For a two-phase system, the degree of crystallinity is given as ... 

Said this, we can let the reader to recall Fig. 1.15, where we depicted amorphous-like phase regions at grain boundaries as the pathways open for preferential diffusion of hydrogen atoms. Apparently, an alloy can benefit from some fraction of amorphous phase to improve kinetics of hydrogen absorption, but complete amorphization of crystalline lattice lowers capacity for storing hydrogen [156]. Mechanochemical activation is therefore a complex process where kinetic and thermodynamic effects must be firstly well understood, and then optimized. 

These two inequalities can be proved for a more general model in which the film is assumed to consist of multiple parallel bands, each band containing an arbitrary fraction of amorphous phase which exhibits multiple relaxation processes. 

Because the 57Vratio is proportional to the specific surface of the mineral and being higher for mica than for talc, it follows that specific surface would always be lower for mica than for talc particles. Then for the same crystaHine amount of the polypropylene matrix, a higher fraction of amorphous phase involved in the coating of talc particles than in the coating of mica particles would be expected. 

The thickness of the lamellar crystals in PHB spherulites was also found to vary with crystallization temperature but is uniformly low, typically around 6-7 nm. Representing fewer than 10 repeat units per fold stem and in view of the high degree of crystallinity, this again leaves little room for looseness in the fold structure. A large number of folds must be made within the small volume fraction of amorphous phase available. 

When the total mass fraction of each phase is not equal to one, the mass fraction of amorphous phase in the sample can be estimated. 

Measurement of e allows N, the number of orientable dipoles per cm to be determined. In a fully crystalline sample Nc is zero. For a fully amorphous sample, N must be determined Na) and then N determined for the semicrystalline polymer Nj. The fraction of orientable dipoles is then directly proportional to the volume fraction of amorphous phase (A) ... 

It should be pointed out that the relatively small difference between solubility parameters of emcamide with two polymers studied indicates that other influences are also important, such as crystallization during part cooling (see Figure 5.7), which decreases the fraction of amorphous phase and helps to drive the agent to the surface and temperature (high during processing increases compatibility, and low after part formation decreases compatibility). 

Figure 4.22 DMA relaxation strength for fraction of amorphous phase versus amorphous content for lactose.

The fact that the thickness of the interphase estimated here stays unchanged at 34A in the molecular weight range of 30,000-100,000, while the mass fraction and thickness of amorphous phase change remarkably, is particularly meaningful. Flory et al. [6,7] anticipated in 1984 based on their lattice theory that the methylene chains that emerge from the basal plane of lamellar crys-... 

The mass fraction of each phase that was obtained by the line shape analysis of the CH2 resonance line at different temperatures is summarized in Table 12 with Tic. It can be seen that the mass fraction of the crystalline phase (degree of crystallinity) stays unchanged at 0.57 over the wide temperature range from room temperature to 110 °C, while the amorphous phase increases and the interphase decreases with increasing temperature. The Tic of the CH2 carbon in each phase is mostly unchanged over the temperature range examined 65 70 s for the crystalline phase, 0.18 0.21 s for amorphous phase, and 7.0-7.5 s for the interphase. This shows that the molecular motion of each phase in the Tic time frame is almost the same either in the glassy or rubbery state. 

At temperatures below the melting point of the polymer, in region CD, retention proceeds by bulk sorption but the polymer-solute interaction is restricted to the amorphous domains of the stationary phase. Upon meltir, in r on DF, the fraction of amorphous material increases, leading to an incre in retention volume. At temperatures above the melting point, segment FG, a linear retention diagram, corresponding to bulk sorption into the completely amorphous polymer, is obtained. By extrapolation of this line to lower temperatures (dashed line FE), the crystalline content of the stationary phase can be determined by comparison of the experimental retention volume with the extrapolated value. 

Fig. 3.11. Normalized fraction of amorphous material Xa derived from the saturation magnetization vs. milling time. The dashed line corresponds to the amorphous-phase production rate dX,/dt...

When the blends are subjected to tensile testing, a certain fraction of the overall strain is accommodated by conservative deformation of the material. In the PP matrix, deformation results from the combination of amorphous phase hyperelasticity and crystal plasticity, as discussed earlier (50). The PA6 phase is also capable of deforming plastically, but its flow stress in the plastic stage is much higher than that of PP. Consequently, in the PP/PA6 blends the isolated PA6 particles exhibit less... 

Fig. 4. Fractions of crystalline phases (Na2CQ3, Nb205 and NaNbOs) and XRD-amorphous phase, determined by Rietveld refinement analysis, as a function of milling time, a) Na2C03 and Nb20s, b) NaNbOs and XRD-amorphous phase. The inset of b) shows an enlarged view of the curves in the initial 80 hours of milling. The lines are drawn as a guide for the eye (from Rojac et al., 2008b).

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