Dilatometry application

Pannetier and Souchay have reported the data below as an example of the application of dilatometry to kinetics studies. 

Dilatometry is one of the older classic methods for the determination of transition points between solids (Drucker 1925). The dilatometer usually consists of a large bulb connected to a capillary and filled with an inert liquid. Volume changes as a function of temperature or resulting from a solid-solid transition may be determined by changes in the volume of the inert liquid. The recent advances in the miniaturization of chemical instrumentation (e.g. Jakeway ef a/. 2000 Krishnanefa/. 2001), and the high precision associated with that miniaturization may lead to a renaissance of the use of some of these classic techniques and their applications to the study of polymorphism. 

Solid Fat Content Many methods for measuring SFC have been developed. These include dilatometry, calorimetry, and pulsed nuclear magnetic resonance (pNMR). Dilatometry and calorimetry use measurements of volume or heat content ratios between the completely liquid and the completely solid states (42). Dilatometry and calorimetry methods are time consuming and tend to be applicable only when the SFC is less than 50% (42). Therefore, pNMR has become the most commonly used method for SFC determination. 

Water soluble synthetic polyelectrolytes have attracted increasing attention in recent years, mainly because of their wide utility in industrial applications, and also because of their resemblance to biopolymers. PolyCmethacrylic acid), PMA, a wea)c polyelectrolyte, exhibits a mar)ced pH induced conformational transition. A wide variety of techniques have been employed to gain more information on the nature of the conformational transition of PMA, these techniques include viscometry, potential titrimetry,(1-5) Raman spectrometry,(6) calorimetry,(7-9) electrical conductometry,(10) dilatometry,(11) H NMR linewidth,(12) viscoelastic studies,(13) )cinetics of chemical reactions, (14) small-angle neutron scattering,(15) pH jump,(16,17) and fluorescent probing.(18-27)... 

Techniques which are more specific to the various morphological states, especially the amorphous domain, are needed. NMR and ESR are two such molecular probes. By monitoring the mobilities of protons as a function of temperature, Bergmann has defined the onset of molecular motion in various polymers (14). The applicability of NMR as a measure of molecular motion in polymer solids has been the subject of several reviews 15,16,17). ESR monitors the rotational and translational properties of stable radicals, usually nitroxides, and relates their mobilities to polymeric transitions. As stated in several works (18,19), the radical s sensitivity to freedom of motion of the polymer chain is infiuenced by its size, shape, and polarity. The above probes are both high frequency in nature, 10 -10 Hz. Measurement at high frequency has decreased resolving power for the various transitions in contrast to low frequency or static experiments, such a dilatometry with an effective frequency of 10 Hz (20). 

There are three main areas in which wide-line NMR can find application in the edible oils and fats field as a replacement for dilatometry in the determination of solid fat contents, for determination of the fat in foods, and for determination of the oil content of oil seeds and meals. In addition, NMR is finding increasing application in the heavy oils and fats and petrochemicals industry (Waddington, 1981). 

The truly impressive feature of NELF is that it is a completely predictive model of small molecule sorption in glassy polymers, if information about the polymer partial density, P2, is known. Unfortunately, P2 is obtained firom dilatometry data, and these data exist for only a very small number of penetrant-polymer systems, which limits the general practical applicability of the model. In light of this shortcoming, two approaches have been used to make NELF more widely applicable. The first approach assumes that the pol5mier partial density is equal to the density of the pure polymer, p2° (96). This approach limits NELF to low pressures, where no polymer swelling occurs however, in this pressure range, NELF is still completely predictive. The second approach to increase the applicability of NELF introduces one or two adjustable parameters (95). In this approach, the poljnner partial density is assumed to vary linearly with pressure such that... 

Reduction in surface area and open porosity for a powdered sample is not readily measured by dilatometry. Density, BET adsorption isotherms, or emanation thermal analysis (ETA) are the applicable techniques. The latter is accomplished in a scanning temperature mode and, therefore, is capable of more rapidly identifying the significant temperature regimes. ETA involves substantial effort in sample preparation, however. A radioactive gas or its parent must be incorporated into the... 

SAXS is a widely used method for the investigation of lamellar structure in the two phase systems. To obtain structural parameters, such as the average crystal separation and crystal thickness, the one dimensional elecbon density correlation function is often used. In syndiotactic poly(propylene) the one dimensional model calculation [24] can be applied since the amorphous phase and crystalline phase form one-dimensional stacks of crystalline lamellae. But in the case of monoclinic iPP, electron microscopy reveals the existence of unique cross-hatched lamellar stracture [25-30], and the applicability of the one dimensional model has been questioned by Albrecht and Strobl [31]. These researchers used SAXS and dilatometry to study structure development in PP, and presented a scheme to check for the feilure of the... 

With this brief discussion of the functions needed for thermal analysis and the basic theories of the description of matter we are now ready to treat the various thermal analysis techniques one at a time. In this text we start with the simplest measurement, thermometry, go to the most basic techniques, differential thermal analysis and calorimetry, and finish with thermomechanical analysis, dilatometry, and thermogravimetry. Each of the techniques is illustrated with a selection of problems fi om various applications of thermal analysis. An effort has been made to cover as many types as possible, but also to try to avoid any duplication of the description of the phenomena to be measured. A detailed discussion of any particular aspect of melting, for example, will thus only be given for the techniques where it can most easily be measured. If other techniques can achieve the same, reference will be made to where the full description is given. 

Two applications of equilibrium dilatometry can be irrunediately suggested the absolute determination of volume or density within the one-phase areas, and the detection of transition temperatures by tracing through the two-phase areas along an isobar. The latter can also be extended to multicomponent systems as is discussed in Sects. 3.5 and 4.6 for the changes in caloric functions. The transition temperatures can be identified by either quantitative or qualitative determination of the volume changes. Several applications are given in Sect. 6.5. Nonequilibrium transitions and kinetics can be followed by dilatometry in the same marmer as that discussed for kinetics by calorimetry (Sect. 4.7). 

Thermomechanical analysis thus permits a quick comparison of different materials. As long as instrumental and measuring parameters are kept constant, quantitative comparisons are possible. In Sect. 6.5, some more detailed applications of dilatometry and thermomechanical analysis to melting and crystallization are collected, as well as a discussion of the analysis of materials under tension. 

A few other thermal techniques such as thermomechanical analysis, dilatometry, emanation analysis, etc., are only used to a limited extent in concrete investigations. Several publications have appeared whieh exclusively deal with the application of thermal analysis to the investigation of cementitious systems. ... 

Thermal methods (DTA, TG, TMA, and dilatometry) are well-established investigative tools in clay science and related industrial applications.Clay brick manufacturers have employed these techniques to optimize their plant production procedures. 

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