Thermal analysis of polymers

Thermal analysis techniques are designed to measure the above mentioned transitions both by measurements of heat capacity and mechanical modulus (stiffness). 

Thermo-analytical methods are powerful tools in the hands of the polymer scientist. Thermometry is the simplest and oldest method in thermal analysis. A sample is heated by a constant heat flow rate. Any phase transition is recorded as an invariance in temperature. 

The number of phenomena which can be directly studied by thermal analysis (DSC (DTA), TG, TMA, DMTA, TOA and DETA) is impressive. Typical of these methods is that only small amounts of sample (a few milligrams) are required for the analysis. Calorimetric methods record exo- and endothermic processes, e.g. melting, crystallization, liquid-crystalline phase transitions, and chemical reactions, e.g. polymerization, curing, depolymerization and degradation. Second-order transitions, e.g. glass transitions, are readily revealed by the calorimetric methods. Thermodynamic quantities, e.g. specific heat, are sensitively determined. TG is a valuable tool for the determination of the content of volatile species and fillers in polymeric materials and also for studies of polymer degradation. The majority of the aforementioned physical transitions can also be monitored by TMA (dilatometry). DMTA and DETA 

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Report 95 Thermal Analysis of Polymers, M. P. Sepe, Dickten Masch Manufacturing Co. 

Calorimetry and Thermal Analysis of Polymers (V. B. F. Mathot, ed.), Hanser Publishers, New York, 1994. 

Androsch, R., Stolp, M., and Radusch, H.-J. (1996). Simultaneous X-ray diffraction and differential thermal analysis of polymers. Thermochim. Acta Dev. Calorim. 1995,271,1-8. 

Accurate temperature calibration using the ASTM temperature standards [131, 132] is common practice for DSC and DTA. Calibration of thermobalances is more cumbersome. The key to proper use of TGA is to recognise that the decomposition temperatures measured are procedural and dependent on both sample and instrument related parameters [30]. Considerable experimental control must be exercised at all stages of the technique to ensure adequate reproducibility on a comparative basis. For (intralaboratory) standardisation purposes it is absolutely required to respect and report a number of measurement variables. ICTA recommendations should be followed [133-135] and should accompany the TG record. During the course of experiments the optimum conditions should be standardised and maintained within a given series of samples. Affolter and coworkers [136] have described interlaboratory tests on thermal analysis of polymers. 

Nakamura S, Todoki M, Nakamura K, Kanetsuna H (1988) Thermal analysis of polymer samples by a round robin method. Part I. Reprodubility of melting, crystallization and glass transition temperatures. Thermochim Acta 136 163-178 Ozawa T (1965) A new method of analyzing thermogravimetric data. Bull Chem Soc Jpn 88 1881-1886... 

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