TMA curves

One of the more recently exploited forms of thermal analysis is the group of techniques known as thermomechanical analysis (TMA). These techniques are based on the measurement of mechanical properties such as expansion, contraction, extension or penetration of materials as a function of temperature. TMA curves obtained in this way are characteristic of the sample. The technique has obvious practical value in the study and assessment of the mechanical properties of materials. Measurements over the temperature range - 100°C to 1000°C may be made. Figure 11.19 shows a study of a polymeric material based upon linear expansion measurements. 

Figure 14.8. Thermal mechanical analysis (TMA) curve of 10FEDA/4FMPD film cured at 350°C...

For example, the fluorinated copoly imide with 10 mol% 6FDA/TFDB has almost the same CTE as a Si substrate. Figure 15.8 shows the TMA curves, temperature vs. elongation, of the fluorinated copolyimides with 10 mol%... 

Figure 15.8. TMA curves of copolyimides containing 10 and 100 mol% 6FDA/TFDB.

Figure 15.23. Normalized elongation in TMA curves All, vs. in-plane birefringence of polyimide films.

Fig. 4 Theoretical TMA curves for glass transition Tg and polymorphic transition.

Figure 3.54. T) pical TMA curves for a motor-winding wire. Reprinted from Figure 42 (Prime, 1997). Copyright (1997), with permission from Elsevier.

We did not observe two ferromagnetic phases, Fe2.2C (c phase) and Fes04, as previously observed by TMA in carburized iron (1,2). This diflFerence in the studies is probably attributable to differences in catalyst compositions and reaction conditions. In a few but not all instances of Ref. 2, the assignment of Fes04 of an inflection at about 825 K in the TMA curve appears to be incorrect because the inflection disappeared upon cooling. This disappearance is a strong indication of a thermal reaction between Fe and FesC. 

Figure 16.39 TMA curves of textured and untextured fibers measured in tension, showing...

Figure 16.40 TMA curves of three types of polymer fiber, showing shrinkage due to stress relaxation before melting in polymers 2 and 3. (Courtesy of Netzsch Instruments, Inc., Paoli, PA.)...

This is in general valid for MUFs, UFs, and PFs, but the effect is particularly evident for the MUF resins [35]. Decreases in MUF resin solids content of as much as 33% while conserving the same performance are reported in the case of wood particleboard. In Fig. 6 are shown the continuous heating rate TMA curves of modulus as a function of temperature for an MUF resin of 1 1.2 (M- -U) F molar ratio. Similar but much less extreme... 

In Imai et al. (1983), glass transition temperatures were determined from DTA and TMA curves. Also, decomposition temperatures were determined as the temperature at which 10% weight loss occurred, as determined by TGA. 

Figure 2. Thermomechanical analysis (TMA) curves of modulus of elasticity (MOE) as a function of temperature for PF resin with different percentages of NaMMT added.

The probe displacement is calibrated using a micrometer or standard gauges whose thickness is precisely known. The applied load is calibrated using standard masses. On completion of the calibration procedures the instrument should be run under the proposed experimental conditions without the sample and the TMA curve recorded. This curve can be used later to correct for artefacts in the data which originate in the instrument. 

Determination of the linear thermal expansion coefficient (a) from a TMA curve... 

Figure 14.8. Thermal mechanical analysis (TMA) curve of 10FEDA/4FMPD film cured at 350°C (reproduced by permission of the American Chemical Society, from Ando et al ). ...

---