Torsional Braid Analyzer

Torsional Braid Analyzer (TBA) B 10- -1 Plastics Analysis Instmments, Princeton, N.J. 

Free- Vibration Methods. Free-vibration instruments subject a specimen to a displacement and allow it to vibrate freely. The oscillations are monitored for frequency and damping characteristics as they disappear. The displacement is repeated again and again as the specimen is heated or cooled. The results are used to calculate storage and loss modulus data. The torsional pendulum and torsional braid analyzer (TBA) are examples of free-vibration instruments. 

Torsional Braid Analyzer Plastics Analysis Consultants... 

Rubber-toughened epoxy resins have been characterized by their resin and rubber glass transition temperatures (57) using torsional braid analysis (TEA). These are reported in the literature as eTg and rTg, respectively. The Torsional Braid Analyzer has also been used to characterize ATBN-modifled coatings regarding transition temperatures. 

Torsion-braid analyzer n. An instrument which permits the measurement of thermomechanical properties of polymers that are undergoing structural changes during cure. Shah V (1998) Handbook of plastics testing technology. John Wiley and Sons, New York. 

Free resonance analyzers normally are limited to rod or rectangular samples or materials that can be impregnated onto a braid. This last approach is how the curing studies on epoxy and other resin systems were done in torsion and gives these instruments the name of torsional braid analyzers (TEA). 

Free vibration and forced vibration methods have been employed to determine the respective data. Free vibration was common earlier in polymer blend studies, but forced vibration data is much more common today due to the availability of more sophisticated testing equipment. Free vibration methods include the torsion pendulum, the vibrating reed and the torsional braid analyzer. The torsion pendulum is comprised of an inertial source (disk or rod), which can freely vibrate and is attached to a specimen, which is rigidly fixed at one end. Upon angular deformation of the inertial source and releasing, a damped sinusoidal curve depicts the resultant deformation of the sample [18,19]. Tan S can be calculated from... 

Dynamic mechanical analysis is quite useful to observe the result of chemical reactions of polymer chains (e.g., transesterification) as evidenced by Figs. 3.12 and 3.13 [26]. The DMA method can be applied isothermally to determine crystallization kinetics (modulus versus time measurements) [13, 27] and reaction rate of thermosetting materials (e.g., epoxy) [28]. For reaction rate determination of liquid systems, the torsional braid analyzer is most appropriate as the braid can be saturated with the prepolymer liquid. A cellulose blotter could be used for the torsion pendulum, and a section of nylon hosiery could be used for forced vibration studies (both supports saturated with liquid prepolymer). 

---