Quenched sample annealing

Sankar et al [48] have studied A/B block copolymers of polystyrene (PS) and poly(methylmethacrylate) (PMMA) by observation of C-detected where neither, one or the other, and both blocks were perdeuterated. They found that the carbons in each block of the copolymers were experiencing primarily their own protons, indicating some degree of phase separation, but the for each block differed somewhat from the measured for the PS and PMMA homopolymers. Annealing quenched samples apparently increased the degree of phase separation, because their values more closely approached the homopolymer values. 

Fig. 3 shows results of Wirotest 202 A indications as a function of compressive stress for cylindrical samples d> 18 mm made of steel LH 15, what is turn indieates that the dependence of indications on compressive stress is linear in the range up to 180 MPa with regard of quenched (1) and up 120 MPa with regard to annealed (2) samples. 

The x-ray diffractograms of those three samples are shown in Fig. 12. The lower pattern corresponds to the quenched sample where only the mesophase is present (the layer line, appearing at lower angles is not shown). The other two diagrams corresponding to the annealed samples present several sharp diffraction peaks, which... 

In Fig. 5.1, the densities of the annealed and of the quenched polymers are plotted against Mh the inverse molecular mass of the network strands. All the annealed samples were denser by about 0.15% than the quenched ones. Bero and Plazek [52] observed an effect of similar magnitude between quenched samples and samples cooled at 0.2 K/h. 

Fig. 5.3. Young s moduli Efle, as determined by flexural tests on small samples after thermal treatment are plotted against the densities of those samples. The dots are situated along a single line since the annealed samples are denser and more rigid than the quenched samples prepared from the same polymer...

Fig. 17 Section of Ca-Au Ga phase diagram showing the distribution of 1/0, 1/1, 2/1 ACs in samples that were slowly cooled from 800°C and annealed at 500°C. Note that the i-QC is obtained only in quenched samples near CaAujGaj (marked by the arrow)...

Samples quenched from high temperature (1100°C for Nd2 xCexCu04, 890°C for Nd2Cu04 xFx) contain little or no superlattice. On annealing these samples at 400-700°C regions of superlattice form within minutes this process can be observed directly in the electron microscope by means of a hot stage. 

The rate of cooling from above the melting temperature has significant effects on lamellar thickness and perfection as well as on physical properties. " There is a progressive increase in lamellar thickness and measured density with slower rates of cooling from 380°C. Quenched specimens, in our work, have a specific gravity of 2.136 g/cm compared to 2.180 0.003 for specimens cooled at die very slow rate of 0.02 deg/min. Annealing a quenched sample for 5 hours at 312°C causes die density to increase to 2.158 g/cm. For perspective, the density of totally noncrystalline PTFE is estimated to be 2.00 and the perfect-crystal density is 2.301 g/cm by X-ray diffraction. 

For polypropylene, by using the spectrum of an annealed sample and subtracting it from a quenched sample it is possible to obtain a difference spectrum characteristic of the amorphous regions of polypropylene 210). In Fig. 13, the difference spectrum characteristics of the amorphous phase of the quenched sample (a) is compared with the difference spectrum characteristic of the ordered phase of an annealed... 

Fig. 13 a. Difference spectrum characteristic of the amorphous phase of the quenched sample b) difference spectrum characteristic of the ordered phase of the annealed sample. 

DETERMINED DILATOMETRICALLY DETERMINED BY DTA ON ANNEALED SAMPLES O MANDELKERNetal DTA QUENCHED SAMPLE... 

The sample treatment is executed as follows The sample is located inside the chamber. The SFM scanner is retracted by about 8 mm from the sample. Then the chamber is closed by the lid. In order to anneal the sample successfully, we perform the treatment in a hermetically sealed reactor chamber. The sample is exposed to chloroform vapor while a voltage is applied across the electrodes on the glass substrate. The gas flow rate through the system is controlled by mass flow controllers and additionally checked by a flow meter installed at the outlet of the chamber. After a certain annealing time, the solvent is removed with a flow of pure argon while the voltage is still applied in order to quench the structure in the presence of the electric field. Subsequently the lid is opened, the voltage is switched off, and the SFM scanner is moved towards the sample. This procedure is repeated several times. The accomplishable position stability as a key performance feature of the quasi in situ SFM amounts to almost the same value as reported in [32] (low pressure plasma treatments). The increase in lateral drift is only about 23 nm per process step. The... 

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]...

Slow cooling from the melt at 0.31°C/min results in only minor changes in the Cp curve. Annealing of a quenched sample near its Tg, on the other hand, produces noticeable differences in the thermal scan. 

Comparison between the Crystallization from the Melt or the Glass. The crystallization studies at low temperatures can either be performed on samples cooled from the melt to the crystallization temperature or on quenched samples which are annealed to the crystallization temperature. Each method would be indicated for the particular region where equilibration to the crystallization temperature would be faster without having induced crystallinity in the amorphous polymer. In general, crystallization from the melt is better at temperatures above that which gives the maximum in growth rate, and crystallization from the glass is better for temperatures lower than the maximum. 

A consequence of the afore-mentioned slow transitions would be a rather strong dependence of the actual structure observed at room temperature upon the previous thermal history of the sample. For example, quenched samples around Na0i35WO3 may be cubic, while slowly annealed samples would be tetragonal (II). Conversely, samples of low sodium content may be cubic if they have been prepared by extracting sodium vapor at temperatures of 600° to 700°. The existence of two-phase regions may account for some of the difficulties we (and others) have had in growing single crystals of low-sodium bronzes by the electrolytic method. 

The time dependence of the early stages of polymer interdiffusion at interfaces is indicative of the diffusion process. The normal approach to study such interdiffusion by neutron reflectivity is to use an anneal/quench cycle where the sample is heated for a given time above the glass transition temperature (Tg) of the polymer, then quenched rapidly to room temperature, after which the reflectivity profile is measured. This has proved to be highly effective for a number of systems, but is difficult to apply when Tg is room temperature, or for small molecule ingress into a higher molecular weight polymer layer. 

Samples of PET/PEN copolymers with 10, 20, 30, 50, 80 and 100 mol% PEN have been synthesized. Amorphous films of the samples were obtained by melt pressing above the melting point and quenching in ice-water. The samples were then crystallized by annealing the glassy materials at various temperatures. The degree of crystallinity was calculated from the amorphous density measured on quenched samples and from the crystal density derived from the crystal unit cell. 

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