Tension mode, thermomechanical

Thermomechanical analysis in the tension mode can be employed in the production of films and fibers to follow the consistency of the product during manufacturing, and to characterize properties of the product, such as CLTE, thermal shrinkage and shrinkage force, and physical properties like Tg and T. All these properties are important, and they determine the end-use possibilities. For example, matching fiber-matrix expansion properties is necessary to avoid delamination of components, such as in tire cords. Shrinkage (i.e., irreversible contraction) is important to avoid in textiles for safe ironing, and it is also an important property in heat-shrink films (Jaffe et al. 1997). 

Thermomechanical measurements can be carried out on a wide range of solid samples. The most usual mode of measurement is either in compression (for self-supporting samples) or tension (for thin films and fibres). Some materials exhibit anisotropic behaviour (particularly films or crystals) in that changes in dimensions will differ depending upon which axis the measurements are performed. 

Thermomechanical analysis (TMA) measures the deformation of a material contacted hy a mechanical prohe, as a function of a controlled temperature program, or time at constant temperature. TMA experiments are generally conducted imder static loading with a variety of probe configurations in expansion, compression, penetration, tension, or flexime. In addition, various attachments are available to allow the instrument to operate in special modes, such as stress relaxation, creep, tensile loading of films and fibers, flexural loading, parallel-plate rheometry, and volume dilatometry. The type of probe used determines the mode of operation of the instrument, the manner in which stress is apphed to the sample, and the amount of that stress. 

Thermomechanical analysis (TMA) is a technique in which the deformation of a substance under a nonoscilla-tory load is measured as a function of temperature while the substance is subjected to a controlled temperature program. It is used extensively in polymer studies. The mode, as determined by the type of stress applied (compression, tension, flexture, or torsion), should always be noted. As already stated, dynamic mechanical analysis is a technique in which the viscoleastic response of a sample under an oscillatory stress is studied while the substance is subjected to a temperature regime. Torsional braid analysis is a particular case of dynamic thermomechanometry where the material is supported. 

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