Dilatometry measurement

Volume dilatometry measures changes in the specific volume, the reciprocal of density. The degree of crystallinity is calculated using the assumptions that ... 

Most of the thermal expansion coefficients were determined by volume dilatometry. Measurement of the buoyancy in a liquid whose density is accuratdy known as a function of temperature is also an accurate method. Some values were determined from refractive index data at different temperatures, assuming the molar refraction to be a constant. Values reported as v dv/dT were converted to dv/dT where necessary by the use of available density data. Linear coefficients of expansion were simply multiplied by three to obtain v Mv/dT, then converted to dv/dT using reported densities. 

Sample holders have most often tubular or rod shapes and are made of quartz (for temperatures up to 1100 °C), alumina (up to 1680 °C), graphite (up to 2800 °C) or tungsten (up to 3400 °C). The dilatometry measurements include initially both sample and holder dimensional changes, later on the results being corrected using reference materials [22]. 

The value of n can be obtained from dilatometry measurements by relating the extent of crystallization, namely (Mo - Mi) Mo to the polymer concentration. The total volume of polymer partially solidified at time t is given by... 

Dielectric, NMR and low frequency dynamic mechanical studies indicate that the transition detected acoustically at 193 K can be ascribed to the onset of oscillatory motion of the phenyl group. Transitions observed at 383 K and 373 K are attributed to the glass transition and this assignment has been confirmed by dilatometry measurements. The observation of two transitions leads to the suggestion that clustering occurs in the solid phase. The lower temperature transition would therefore correspond to the onset of collective motions of polymer chains in the amorphous regions. The low temperature dependence of the modulus between 373 K and 383 K is believed to be... 

Dilatometry measurement of the change in water (or oil) level in an initially filled tube no exchange of material with the environment takes place (see Figure 3.6)... 

As-polymerized PVDC does not have a well-defined glass-transition temperature because of its high crystallinity. However, a sample can be melted at 210°C and quenched rapidly to an amorphous state at <—20°C. The amorphous polymer has a glass-transition temperature of — 17°C as shown by dilatometry (70). Glass-transition temperature values of —19 to — 11°C, depending on both method of measurement and sample preparation, have been determined. 

Ceramic bond formation and grain growth by diffusion are the two prominent reactions for bonding at the high temperature (1100 to 1370°C, or 2000 to 2500°F, for iron ore) employed. The minimum temperature required for sintering may be measured by modern dilatometry techniques, as well as by differential scanning calorimetry. See Compo et al. [Powder Tech., 51(1), 87 (1987) Paiticle Characterization, 1, 171 (1984)] for reviews. 

The procedures of measuring changes in some physical or mechanical property as a sample is heated, or alternatively as it is held at constant temperature, constitute the family of thermoanalytical methods of characterisation. A partial list of these procedures is differential thermal analysis, differential scanning calorimetry, dilatometry, thermogravimetry. A detailed overview of these and several related techniques is by Gallagher (1992). 

It was concluded that dilatometry was the most reliable method and water absorption is difficult to determine. Both methods use appreciable quantities of film, which contain both D and / areas. Resistance measurements, however, can be carried out on small areas of film and the relative properties of D and / areas studied. 

Using dilatometry in parallel with cyclic voltammetry (CV) measurements in lmolL 1 LiC104 EC-l,2-dimethoxy-ethane (DME), Besenhard et al. [87] found that over the voltage range of about 0.8-0.3 V (vs. Li/Li+), the HOPG crystal expands by up to 150 percent. Some of this expansion seems to be reversible, as up to 50 percent contraction due to partial deintercalation of solvated lithium cations was observed on the return step of the CV. It was concluded [87] that film formation occurs via chemical reduction of a solvated graphite intercalation compound (GIC) and that the permselective film (SEI) in fact penetrates into the bulk of the HOPG. It is important to repeat the tests conducted by Besenhard et al. [87] in other EC-based electrolytes in order to determine the severity of this phenomenon. 

The kinetics of cleavage of some of these compounds have been measured by dilatometry and in other acidic media, and the rate coefficients and relative rates are given in Table 233658, 673, 686, 687. It can be seen that there is relatively little variation in the spread of rate coefficients with change in the acid and this argues against nucleophilic participation of the acid in the rate-determining step... 

The copolymers consist of strictly alternating sequences of diene and olefin. C-NMR measurements Showed the microstructure of the butadiene units in BPR to be exclusively of the trans-1,4 configuration (Figure 8). The isoprene units in isoprene-ethylene copolymer (IER) contain 84 % trans-1,4, 15 % cis-1,4, and 1 % 3,4 structures (Figure 9). Spontaneous crystallization in unstretched BPR samples was detected by dilatometry and confirmed by X-ray diffraction and DSC measurements. The extrapolated equilibrium melting point is about -10 °C. 

The R was always sufficiently low for it to be measured by dilatometry. The great attraction of these polymerisations for the kineticists was the possibility of estimating or measuring the total concentration of cations in the reaction mixtures. Several different methods of... 

The kinetics were studied by adiabatic calorimetry [18] and high vacuum isothermal dilatometry [21, 22]. The calorimeter and the dilatometers were fitted with electrodes [21] for measuring the conductivity of the reaction mixtures. 

Dilatometric methods. This can be a sensitive method and relies on the different phases taking part in the phase transformation having different coefficients of thermal expansion. The expansion/contraction of a sample is then measured by a dilatometer. Cahn et al. (1987) used dilatometry to examine the order-disorder transformation in a number of alloys in the Ni-Al-Fe system. Figure 4.9 shows an expansion vs temperature plot for a (Ni79.9Al2o.i)o.s7Feo.i3 alloy where a transition from an ordered LI2 compound (7 ) to a two-phase mixture of 7 and a Ni-rich f c.c. Al phase (7) occurs. The method was then used to determine the 7 /(7 + 7O phase boundary as a function of Fe content, at a constant Ni/Al ratio, and the results are shown in Fig. 4.10. The technique has been used on numerous other occasions,... 

A dilatometer consists essentially of a glass tube (the body ), containing the reaction mixture, to which a straight capillary tube is attached (usually, but not always, vertical). The movement of the meniscus of the reaction mixture in the capillary amplifies changes in the volume of the reaction mixture and is measured, as a function of time, with a cathetometer or by some automatic device. Dilatometry has been used for a very long time because it is simple, cheap, convenient and can be made very accurate. 

Dilatometry is a convenient method for measuring polymerization rate. The method is based on a decreasing volume of the examined system along with conversion of monomer to polymer. For simple polymerization, usually carried out in solution in capillary dilatometer, the decrease in volume, Av, is calculated from measurements of the decrease in the level of reacting mixture ho - h = Ah in capillary with radius, r. Using equation ... 

For materials generally, change in expansion (or density) by dilatometry was traditionally the most often used method for measuring Tg. Thermal properties, for example specific heat, are also widely used, particularly the methods of differential thermal analysis". A method for rubbers using DSC is being developed in ISO TC 45 as ISO 22768, but is not yet published. The inflection point on the heat input - temperature curve is usually obtained automatically by the analyser s software but, if obtained manually, is best found from the derivative of the curve. 

Digestibility, protein quality analysis in vitro, 131, 134, 136-139 in vivo, 127-128, 136-139 Dilatometry, to measure fat, 571 -572 Dimethyl sulfoxide (DMSO), plant cell wall, isolation, 706, 708 2,4-Dinitrophenylhydrazine (DNPH), determination of carbonyl compounds, 553-554, 558 (fig.) Diphenol oxidases inhibitors, 392... 

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