Melt quenching

Fig. 3 Annealing isotherm of the amorphous melt-quenched PET sample at 80 °C [7]...

Fig. 5 Difference intensity SAXS curves of PET after subtraction of the intensity of the melt-quench sample crystallized from the glassy state at 80 C for 3-122 min (a) and 157-313 min (b) [7]...

First, let s examine the case of sPS [12]. Figure 14 shows the FT-IR spectra of this polymer the lower and upper parts of the figure are the spectra for samples, melt-quenched and annealed at 120 °C for 400 min, respectively. The latter shows that the crystal form is a phase with an all-trans conformation [56,57]. As seen from this figure, several absorption bands at 538, 935, 1224, and 1335 cm-1 vary with annealing or crystallization. Of these, the band at 1224 cm-1 was assigned to the crystalline packing, and some bands around 538 cm-1 were related to the conformational changes by Kobayashi et al. [56]. 

Fig.28 Characteristic wavelength A as a function of quenching or jumping-up temperature Tx [16]. ( ) quenched from the molten state, (A) jumped up from the glassy state. The dotted line represents a fitting curve with Eq. 14 for the melt quenching...

Khulbe, P. K. Wright, E. M. Mansuripur, M. 2000. Crystallization behavior of as-deposited, melt quenched, and primed amorphous states of Ge2Sb2.3Te5 films. /. Appl. Phys. 88 3926-3933. 

Continuous laser melt quenching of hypoeutectic Ag-Cu alloys has been performed and discussed by Copley et al. (1995) nano-phase coupled growth structures (with spacing of 10 nm) have been observed in banded nano-structures. 

It is important to describe the preparation of these samples, which were annealed at high temperature in dry nitrogen gas and then rapidly quenched in liquid nitrogen. Because they were thereby rendered amorphous, there was no scattering due to the PTFE-like crystallinity that would complicate the data interpretation. Membranes were boiled in NiCL solutions and then soaked in H2O, D2O, and H2O/ D2O = 50 50 solutions. Due to the elimination of crystallinity from the melt-quench pretreatment, these samples were considerably hydrated at 41 vol %. 

The factor governing the final size and morphology (from millimetre-sized to large irregular blocks) of HT materials is the melt quenching... 

The vapour deposition method is widely used to obtain amorphous solids. In this technique, atoms, molecules or ions of the substance (in dilute vapour phase) are deposited on to a substrate maintained at a low temperature. Most vapour-deposited amorphous materials crystallize on heating, but some of them exhibit an intervening second-order transition (akin to the glass transition). Amorphous solid water and methanol show such transitions. The structural features of vapour-deposited amorphous solids are comparable to those of glasses of the same materials prepared by melt-quenching. 

Glassy Sb Sci alloys (x < 0.05) were prepared by conventional melt quenching. Cleaned silica tubes containing a mixture of the appropriate amount of constituents Sb and Se were evacuated to lO Torr and sealed. The contents of the tubes were melted in a furnace and continuously agitated for 10 h to ensure good homogeneity. The melt was rapidly quenched in cold water from 800 K, and the cooling rate was estimated to be 200 K/s. 

Samples investigated were 0.3-3.0 o,m amorphous Sb Sei (0 < x < 0.05) films. These were preferentially prepared by conventional vacuum evaporation onto room-temperature sihca-glass substrates (plates). The a-Sb Sei source material was made by the usual melt-quenching technique. Coohng rate was estimated to be 100-200 K/s. Prior to measurements, the films prepared were aged at laboratory conditions (natural aging) for several weeks to allow their structure to equilibrate. 

Sometimes, small structural differences in morphology of polymer samples can be isolated by using a double subtraction technique. For example, with polyethylene terephthalate) PET, differences in the amorphous phase of the melt-quenched polymer and solution-cast polymer can be isolated by first subtracting out the contribution due to the trans isomer and then subtracting the two difference spectra from each other 214). (Fig. 16) shows the resultingdifference spectrum obtained after the second subtraction. Obviously the two amorphous structures are different from each other. 

Fig. 16. Difference spectrum melt-quenched amorphous component spectrum minus solution-cast amorphous component spectrum.

Fig. 3 AFM images of a CA-g-PLLA film of MS = 22 (melt-quenched), obtained a before and b after the enzymatic hydrolysis for 30 days. The line profiles of the sections were taken along the dotted lines in the respective AFM images. (Rearranged by using data from [30])...

Soft layer thicknesses of about 10 nm are significantly smaller than those obtained in nanocomposites prepared by usual metallurgical routes, such as ribbon melt-quenching or powder metallurgy. Only thin film preparation procedures have allowed films of such small thicknesses to be prepared. For industrial development alternative routes should be developed. Mechanical deformation routes such as rolling might be a possibility. 

Fig. 2 WAXD profiles (a) and the distance distribution functions P(R) (b) of PET as a function of annealing time at 115 °C. M.Q. Melt-quenched sample [6]...

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