Length dilatometry

Bond length Dilatometry Densification Analysis of die Generally 4,... 

This concludes the discussion of thermometry and dilatometry. The tools to measure temperature, length, and volume have now been analyzed. The tools for measurement of heat, the central theme of this book, will take the next three sections and deal with calorimetry, differential scanning calorimetry, and temperature-modulated calorimetry. The mechanical properties which involve dilatometry of systems exposed to different and changing forces, ate summarized in Sect. 4.5. The measurement of the final basic variable of state, mass, is treated in Sect. 4.6 which deals with thermogravimetry. 

Society s Cold Test is used for salad oils. Palm olein is assessed by its cloud point and sometimes by a cold stability test in which the length of time for which the oil remains clear at 18-20 °C is measured. Other tests of importance are the solid fat content by NMR or dilatometry and differential scanning calorimetry. Deffense and Tirtiaux (1982) published HPLC chromatograms for the raw materials and products of the fractionation of palm oil and beef tallow. 

The simplest volume recovery experiment performed is the down-jump. In this experiment, a material initially above Tg and at equilibrium is subjected to a temperature down-jump to an aging temperature Ta below Tg. The isothermal evolution of volume at T, as indicated by the downward arrow in Figure 1, is monitored with time via length or volume dilatometry. Figure 2 shows tjq)i-cal data replotted from Kovacs data (9) for a series of aging temperatures for poly(vinyl acetate). These curves, called intrinsic isotherms, are plotted as the relative departure from equilibrium 5 versus the logarithm of time, with S defined as... 

Three other thermal analysis techniques involve the basic measurement of length or volume and are called thermomechanical analysis (TMA) and dilatometry, respectively. Both techniques are described in Chapter 6, together with a brief survey of dynamic mechanical analysis (DMA). 

The basic functions of state of TMA and dilatometry are length, volume, stress, and pressure, as pointed out in Figs. 2.16-2.17. For DMA, time must be added as explicit variable of the measurements. 

The connection between mass and volume, and thus also length, was the most difficult branch of metrology. Hundreds of units have been described, each pointing to a different method of dilatometry. Once one establishes the basic unit, which today is naturally the SI unit meter (see Fig. 2.16), measurement involves precise subdivision and comparison. 

Dilatometry TD Length or volume change Creep, thermal expansion... 

Monomer conversion can be measured by different means dilatometry, spectrometry, sampling, and gravimetry for variable reaction times Rp is equal to the slope of the straight line drawn from the plot of the monomer conversion versus the reaction time. Knowing Ri, it is relatively easy to obtain k /kf. This value is an important feature of chain polymerizations indeed, for a same rate of initiation, this value is directly proportional to the rate of polymerization of the monomer considered it is also proportional to the average length of the polymer chains formed. Some typical values are given in Table 8.12. 

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