Dilatometric measurements

High-resolution dilatometric measurements have revealed the appearance of anisotropy in the cubic-phase thermal strain in the precursive temperature region for the soft-mode martensitic transformations in VaSi/ Ni-Al, In-Tl/ and SrTiOa In the case of Ni-Al and SiTiOa, the onset temperatures for the strain anisotropy are close to those at which the appearance of central peak behaviour occurs. 

Using data obtained from thermocurrent, piezoelectric and dilatometric measurements, the first and second pyroelectric coefficients were calculated for the Rb5Nb3OFi8 crystal. Fig. 114 presents the results. 

The melting transition in polymers is conveniently observed by dilatometric measurements of the volume as a function of the temperature. Results thus obtained for poly-(N,N -sebacoyl piperazine) are shown in Fig. 129, and for poly-(decamethylene adipate) by the lowest curve in Fig. 130. Most of the melting, as evidenced by the abnormal increase in volume, occurs within a range of 10°, and it terminates abruptly at a temperature which may be defined within 0.5°. The data shown were obtained by raising the temperature... 

The direct evidence that Besenhard et al. presented for the formation of a ternary GIC is the dilatometric measurement of the graphite electrode, which indicates a crystal expansion of 150% at the cointercalation potential. However, this expansion due to solvent cointercalation was never confirmed on the microscopic level. All of the in situ X-ray diffraction (XRD) measurements conducted by different research-... 

The statistical error determined for K is only a limited measure of the accuracy of the dilatometric measurements. Since the main errors will be similar for each measurement, the accuracy of the method is best determined by estimating the limits of error of each individual measurement.The main source of error and its approximate magnitude should be indicated. 

Kempa, P.B., Herrmann, M., and Engel, W. (1998) Dilatometric measurement of phase stabilized ammonium nitrate (CuPSAN) performed by X-ray diffraction. Proc. 29th Inti Ann. Conf. ICT, Karlsruhe, Germany, June 30-July 03,1998, pp. 73/1-73/11. 

Table II shows the experimental data as well as the maximum overall reaction rates of the monomers studied. All figures are average values of at least two preparations—i.e., four dilatometric measurements. The last column gives the reaction rate relative to that of a comparable styrene emulsion under the same conditions of temperature and dose rate whose reaction rate was accepted as unity.

In general, estimates of Tm and T from calorimetric and dilatometric data agree very well. Examples are Tu from dilatometric measurements... 

Materials. Styrene (BDH Chemicals Ltd.) was stabilized with 0.002 % t-butyl catechol. The stabilizer was removed by washing successively with 10 % potassium hydroxide solution and water, drying over calcium chloride for 24 hr, and vacuum distilling. The monomer was kept in a refrigerator until required. Effective removal of inhibitor was checked by gas chromatography and by dilatometric measurement of the rate of bulk thermal polymerization at 60 °C this was 0.080 % hr which compares with a literature value (17) of 0.089 % hr . ... 

Griffith, J. H., and B. G. RA.nby Dilatometric measurements on poly (4-methyl-l-pentene), glass and melt transition temperatures, crystallization rates and unusual density behavior. J. Polymer. Sci. 44, 369—381 (1960). 

The isotherms obtained in dilatometric measurements of the crystallization rate could be fitted with an Avrami (3) type equation only by assuming the existence of a secondary crystallization process much slower than the rate of spherulitic growth observed microscopically, and by taking into account the experimentally determined form of the nucleation rate. The nucleation rate was found to be a first-order process. Assuming that the secondary crystalliza-... 

Fig. 7. Relative change of the lattice parameter in TS-6 along the chain direction as a function of conversion X. Indices m and p refer to monomer and polymer, respectively. The full curve is derived from a continuous dilatometric measurement the dashed curve is calculated according to Ref. by minimizing the elastic energy assuming a ratio Ep/E = 5.0 for the elastic constants of polymer and monomer, respectively. Open circles are X-ray data from Ref. crosses represent data from optical absorption studies...

In the dilatometric measurements, the temperature of the latent volume change due to fusion was measured, while melting evidenced itself in the polarizing microscope as the disappearance of the depolarization due to the birefringence of collagen fibers. 

Continuous Dilatometric Measurement of y-Emulsion Polymerization. Polymerization of vinyl monomers causes a volume contraction up to 27% (vinyl acetate) of the volume of the monomer. This shrinkage is proportional to conversion and can be linearly interpolated, however consult Treloar (37). The dila-... 

With respect to the influence of crystallinity (Wc) on the Tg value it is noteworthy that in earlier dilatometric measurements on the same polymer but in a wider range of Wc values (0-50%) complete dependence was observed (Fakirov, 1978 Simov et al, 1970). It was found that with the rise of Wc, Tg first increases up to 25-30%, and thereafter decreases when a crystallinity of around 50% is reached. The initial increase in Tg is actually related to the mobility-restriction effect of the numerous small crystallites (provided the low-crystallinity samples are obtained via high... 

Measurement of Inert Gas Release. Generally, it is possible to measur either the radioactivity of the gas remaining in the solid or the quantity of th gas released. A typical apparatus, for measurement of the latter and alsi DTA and TDA. is shown in Figures 8.48 and 8.49 (187). A labeled sampl (generally 100 mg), a DTA reference material (A1203), and a sample fo dilatometric measurements are placed in the sample holder. Temperatur measurement is by thermocouples embedded directly into the samples. /... 

Figure 8.48. Reaction chamber for concurrent ETA. DTA, and dilatometric measurements (after Balek [187]). l, activated sample 2. DTA standard 3, dilatometer sample 5, composite thermocouple 6. quartz dilatometer rod 7, quartz vessels 8, supporting pipes 9. metal block 10, quartz outer vessel 11. ground glass joint t2. coolant tube.

The course of the elaidinization reaction can be followed by dilatometric measurements (11), consistency determinations (12), by means of critical demixing temperatures, using aniline or triacetin as a solvent (9), or, more directly, by infrared spectrophotometry (13). 

These mejisurements were made at 25 °C with illumination of the same intensity as in the dilatometric measurements. 

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