Thermomechanical analysis curve

Figure 2.16 Generalized thermomechanical analysis curve for epoxy adhesive.

Figure 3. Comparison of thermomechanical analysis curves of beech wood joints bonded with tan-nin/lignin 50/50 wood adhesive. Variation of the joint MOE as a function of temperature.

Thermomechanical analysis curve Graphical representation of data collected by a thermomechanical analyser where the deformation of the sample is plotted as a function of temperature (scanning mode) or time (isothermal mode). 

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 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 term thermal analysis (TA) is frequently used to describe analytical experimental techniques which investigate the behaviour of a sample as a function of temperature. This definition is too broad to be of practical use. In this book, TA refers to conventional TA techniques such as differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermogravimetry (TG), thermomechanical analysis (TMA) and dynamic mechanical analysis (DMA). A selection of representative TA curves is presented in Figure 1.1. 

This cure temperature region was independently confirmed by differential scanning calorimetry and thermomechanical analysis studies of another comonomer system, m PDM in EBIPMA. First, Fig. 3 shows the DSC analysis of neat m-PDM which indicated the neat m-PDM appears to first melt and then spontaneously polymerize (large exotherm) at 200 C. This is shown by curve (1) and region (3) in the Figure. When the just-polymerized m-PDM is itself scanned, a smooth, "flat" curve (2) is obtained in the regions which earlier showed the endotherm melt and polymerization exotherm behavior of the neat monomer. This shows the material is now virtually fully cured. 

Figure 4.6 shows an application of thermomechanical analysis to the characterization of a composite material, that is, an epoxy printed circuit board material. The Tg is readily determined from this curve. 

Thermomechanical analysis instruments are ideally suited to measure creep. In these experiments the increase in strain is measured with time following the application of a constant stress to the sample, followed by the recovery of the strain when the stress is removed. Figure 4.26 shows a typical TMA creep-recovery curve. In these experiments, an instantaneous compression or tensile stress is applied to the sample, and the time-dependent strain is measured at constant temperature. During the loading cycle, the resultant creep curve... 

With TG it is also possible to determine glass fibres in polymer systems. Fava [261] recorded TG/DTG curves of PP filled with carbonate and fibreglass. TG is an ideal analytical tool for the control of the glass fibre content in composite materials. Since the glass fibre is thermally inert, there is no problem resolving the weight from the resin (by simple subtraction from 100%). Gibbons [151] has analysed additives such as plasticisers, antioxidants, fillers, and reinforcements for PAll, PE, PP and epoxy resins both qualitatively and quantitatively by DSC and thermomechanical analysis. Fig-... 

Thermal expansion coefficients are determined by thermomechanical analysis using a dilatation-penetration probe for adhesive pastes and an extension probe for self-standing films. The output of the thermal analyzer equipped with a dilatation probe is a curve plotting the variation of adhesive thickness as a function of the temperature. 

Figure 10.13 Schematic of a thermomechanical analysis (TMA) thermal expansion curve of an inorganic compound glass (solid curve). The geometrical construction to obtain the dilatometric softening point, A4g, at 10 i =Pas is given. The analogous TMA thermal expansion curve is shown (dotted curve) when a high-fictive-temperature glass sample is heated under load relaxation to a lower-fictive-temperature configurational arrangement can produce an observable contraction as illustrated.

Figure 10.23 Thermomechanical analysis (TMA) parallel-plate viscometry is used to investigate the behaviour of the oxyfluoride glass 32Si02-9AIOi.5-31.5CdF2-18.5PbF2-5.5ZnF2-3.5ErF3 (mol %) in which nanocrystals are homogeneously nucleated above Tg [39]. Description of the viscosity-temperature curves may be found in Section 10.5.6.

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