Advanced thermal analysis

Varna-Nair M and Wunderlich B, "Heat Capacity and other Thermodynamic Properties of Linear Macromolecules", X-Update of the ATHAS (i.e. Advanced Thermal Analysis) Data Bank, a computerized version of the data bank of heat capacities. 

Advanced Thermal Analysis System (ATHAS) Polymer Heat Capacity Data Bank... 

To address our efforts towards correlating the macroscopic-ally measured heat capacity data to their microscopic origin, the data base started in the 1960 s was updated and computerized about five years ago (.8). The data bank is now incorporated within ATHAS, Advanced Thermal Analysis, a laboratory for research and instruction. The data bank maintains a collection of more than 500 publications on heat capacities of polymers which includes all measurements ever reported. The publication list is updated every six months. From each publication the following information is retrieved ... 

The description of thermomechanical and thermoelectrical measurements in a modest chapter such as this is an ambitious exercise. The author has attempted to cover a wide range of methods and applications with the intention of illustrating the diversity of this field whilst emphasising the relationships between the static techniques (such as TMA and TSCA) and the dynamic techniques (dynamic force TMA, DMA and DETA). With the exception of TMA, these methods are often promoted as some of the more advanced thermal analysis techniques. It is hoped that the preceding pages help to dispel this myth without belittling their ability to measure useful properties. 

Pyda et al. (1998) studied in detail the heat capacity of PTT by adiabatic calorimetry, standard DSC and temperature-modulated differential scanning calorimetry (TMDSC) for this measurement. The computation of the heat capacity of solid PTT is based on an approximate group vibrational spectrum and the general Tarasov approach for the skeletal vibrations, using the well-established Advanced Thermal Analysis System (ATHAS) scheme. The experimental heat capacity at constant pressure is first converted to heat capacity at constant volume using the Nemst-Lindemann approximation... 

An Advanced THermal Analysis scheme, the ATHAS scheme has been developed over the years and is described in Sect. 2.3.7. It was created to improve the quantitative aspects of thermal analysis and includes methods of data collection and evaluation (computation). Furthermore, it provides computer courses for distance learning, and a data bank of critically evaluated heat capacities of linear polymers and related compounds, both in downloadable information from the ATHAS website. An abbreviated data bank, of use in connection with the discussions in this book, is collected in Appendix 1. 

Heat capacity is the basic quantity derived from calorimetric measurements, as presented in Sects. 4.2-4A, and is used in the description of thermodynamics, as shown in Sects. 2.1 and 2.2. For a full description of a system, heat capacity information is combined with heats of transition, reaction, etc. hi the present section the measurement and the theory of heat capacity are discussed, leading to a description of the Advanced THermal Analysis System, ATHAS. This system was developed over the last 30 years to increase the precision of thermal analysis of linear macromolecules. 

Conclusions. The heat capacity is one of the few macroscopic quantities with a well-understood link to the microscopic molecular motion. The Advanced Thermal Analysis System displayed in Fig. 2.76 allows to establish empirical addition schemes... 

The Advanced THermal Analysis System was developed in the 1980 s to be able to interpret the heat capacities of linear macromolecules more precisely. In the solid state, the heat capacity is described by contributions from the vibrations of an approximate spectrum. Any deviation is a sign of additional processes, usually conformational disordering or motion. In the liquid state extensive addition schemes based on group contributions have been developed to judge heat of fusion baselines and increases in heat capacity on devitrification at Tg. 

The description of the theory of heat capacity and the application of heat capacity measurements have been given by Wunderlich and other researchers [2,3-17]. The most comprehensive and updated heat capacity data are collected in the ATHAS data bank (Advanced THermal Analysis) which has been developed over the last 25 years by Wunderlich (Chemistry Department, The University of Tetmessee), and coworkers. 

Fig. 2. Heat capacity contributions of the skeletal and group vibrations of solid poly-oxymethylene, calculated by the Advanced Thermal Analysis System (ATHAS). A, C B, C C, group vibrations D, skeletal vibrations. To convert J to cal, divide by 4.184.

Flotherm. Advanced thermal analysis of packaged electronic systems. Flomerics, Inc., Westborough, MA. Higgins, C. 1991. Signetics Corp. presentation, Nov. 

Wunderlich, B. Advanced Thermal Analysis Laboratory (ATHAS), Dept. Chem. University Tennessee, Knoxville, TN 37996 - 1600, USA,... 

Reports on the detailed thermal behaviour of PEEK/HAp composites [as well as other polymer/HAp (nano)composites] are scarce in the literature. Advanced thermal analysis methods, e.g., modulated temperature differential scanning calorimetry (MTDSC) or hyphenated thermoanalytical methods such as thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) or mass spectrometry... 

Figure 9.7 Advanced thermal analysis of melting process for estimation of heat of fusion from apparent heat capacity, Cp(exp) of semicrystaUine poly(trimethylene teraphthalate) PTT [28]. (See color insert.)...

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