Thermal and thermomechanical analysis

Microscopies offer a more integral response. Other techniques such as thermal and thermomechanical analysis, and methods sensitive to local mobility such as nuclear magnetic resonance (NMR), can also be used. 

C.M. Chen and R. Kovacevic, Pinite Element Modelling of Prichon Shr Welding—Thermal and Thermomechanical Analysis, Int. J. Mach. Tools Manuf, Vol 43, 2003, p 1319-1326... 

Blends of polycarbonate with the HIQ polymer described in Section 5.4.2 were found to be miscible. The authors observed by thermal and thermomechanical analysis that the of the blend was greater than that of either pure component, and indeed the of the HIQ component was absent in a blend containing as much as 75% HIQ. They consider the combination of miscibility of LCP with a thermoplastic and a non-intermediate to constitute a novel polymer blend pair. 

Thermal and thermomechanical analyses44 are very important for determining die upper and lower usage temperature of polymeric materials as well as showing how they behave between diose temperature extremes. An especially useful thermal technique for polyurethanes is dynamic mechanical analysis (DMA).45 Uiis is used to study dynamic viscoelastic properties and measures die ability to... 

The microanalytical methods of differential thermal analysis, differential scanning calorimetry, accelerating rate calorimetry, and thermomechanical analysis provide important information about chemical kinetics and thermodynamics but do not provide information about large-scale effects. Although a number of techniques are available for kinetics and heat-of-reaction analysis, a major advantage to heat flow calorimetry is that it better simulates the effects of real process conditions, such as degree of mixing or heat transfer coefficients. 

Thermal characterization by differential scanning calorimetry, thermo-gravimetric analysis, and thermomechanical analysis... 

The analytical techniques used to study changes in physical properties with temperature are called thermal analysis techniques. They include thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermometric titration (TT), and direct injection enthalpimetry, dynamic mechanical analysis (DMA), and thermomechanical analysis (TMA). Thermal analysis techniques are used in... 

Properties relating to performance of completely cured adhesive were determined by mechanical spectroscopy and thermomechanical analysis. Measurement of glass transition temperature and coefficient of thermal expansion was obtained from temperature scanning. 

Information on physical parameters of the molecular structure of polyamide fibers are usually obtained by x-ray diffraction methods, electron and light microscopies, infrared spectroscopy, thermal analyses such as differential thermal analysis, differential scanning calorimetry, and thermomechanical analysis, electron spin resonance, and nuclear magnetic resonance (NMR) spectroscopy. X-ray diffraction provides detailed information on the molecular and fine structures of polyamide fibers. Although the diffraction patterns of polyamide fibers show wide variation, they exhibit usually three distinct regions ... 

The joint use of several thermal techniques enables us to solve more complex problems, e.g. to correlate through the study of TG, DTA and thermomechanical analysis (TMA) dehydration traces of zeolite Linde A and some of its cation-exchanged forms, the single recorded thermal eflFect with the removal of water molecules from a specific structural site [11, 12], or to find, through TG, DTA and thermodilatometry (TD) measurements, the structural relationships between cymrite (BaAl2Si208.H20) and hexagonal barium feldspar [13]. 

Dilatometry and thermomechanical analysis (TMA) are also techniques used to monitor the thermal behavior of fibers. They both employ a sensitive probe in contact with the surface of the sample, and the thermal transitions are detected either by a change in volume or modulus of the sample, respectively. In the latter case, the probe necessarily penetrates the sample surface. A variable transformer records the voltage output that is directly proportional to the degree of displacement of the probe during a thermally induced transition. TMA is a more sensitive technique than either DTA or DSC for detecting thermal transitions. 

Guzatto R., Da Roza M. B., Denardin E. L. G., Samios D. (2009). Dynamical, morphological and mechanical properties of poly (ethylene terephthalate) deformed by plane strain compression. Polymer Testing, Vol. 28, pp. 24-29, ISSN 0142-9418 Karagiannidis P. G., Stergiou A. C., Karayannidis G. P. (2008). Study of crystallinity and thermomechanical analysis of annealed poly (ethylene terephthalate) films. European Polymer Journal, Vol. 44, pp. 1475-1486, ISSN 0014-3057 Keum J. K, Song H. H. (2005). Thermal deformations of oriented noncrystalline poly(ethylene terephthalate) fibers in the presence of mesophases structure. Polymer, 46, pp. 939-945, ISSN 0032-3861... 

Johnston [104, 105] studied the effects of sequence distribution on the 2 of alkyl methacrylate-vinyl chloride and a-methylstyrene-acrylonitrile copolymers by differential scanning calorimetry, differential thermal analysis, and thermomechanical analysis. 

Thermal techniques including differential thermal analysis (DTA), thermogravimet-ric analysis (TGA), and thermomechanical analysis (TM A) are widely used in the characterization of polymers and fibers. The specific thermal behavior of a small amount of fiber sample may provide fingerprinting information that in itself is sufficient to identify a sample. These techniques may be complemented by other methods, including... 

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-... 

Also thermal or thermomechanical analysis, including differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) customarily used to characterize polymers in materials science, can be very valuable when applied to dense or porous membranes. 

The methods discussed in this book are differential photocalorimetry, differential scanning calorimetry, dielectric thermal analysis, differential thermal analysis, dynamic mechanical analysis, evcrived gas analysis, gas chromatography, gas chromatography (oml)ined with mass spectrometry, mass spectrometry, microthermal analysis, thermal volalilisalion, Ihermogravimetric analysis and thermomechanical analysis. 

The thermal and thermomechanical properties of the polymer/HAp composites (glass transition temperature, melting and crystallization behaviour, thermal stability, crosslinking effects, phase composition, modulus, etc.) can be evaluated by thermal analysis methods, like TG, DSC and DMA. Recently, a modulated temperature DSC (MTDSC) technique has been developed that offers extended temperature profile capabilities by, for example, a sinusoidal wave superimposed on the normal linear temperature ramp [326]. The new capabilities of the MTDSC method in comparison with conventional DSC include separation of reversible and non-reversible thermal events, improved resolution of closely occurring and overlapping transitions, and increased sensitivity ofheat capacity measurements [92,327]. 

The viscosity of a material suddenly changes and loses fluidity at the gel point. Techniques to follow this phenomenon as a function of temperature are called thermal analysis techniques. According to the definition of the International Confederation of Thermal Analysis and Calorimetry, thermal analysis is a series of collective techniques to measure the physical properties of a material (or a reaction product) by changing the temperature according to a certain program [212, 213]. There are various thermal analyses depending on the physical properties to be measured. In this section, differential scanning calorimetry (DSC), which is the technique to measure heat capacity of the sample, and thermomechanical analysis (TMA), which measures the viscosity or modulus, will be discussed. 

Important insights regarding the interrelationship of exposure time and Iq have been reported for photoinitiated crosslinking (by radical polymerization) of highly functional acrylated resins. Based on simultaneous differential scanning calorimetry (DSC) and thermomechanical analysis (TMA), these elegant studies demonstrate that percent conversions are limited by rapid formation of highly crosslinked domains with immobilized radicals, the reactivity of which is essentially unaffected by continued irradiation. Conversions increased with temperature, as expected for thermal mobilization of the trapped radicals. 

Hong, B. Z., Thomal Fatigue Analysis of a CBGA Package with Lead-Free Solder Fillets, Proceedings of the 6 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 205-211 (1998). 

Thermal analysis helps in measuring the various physical properties of the polymers. In this technique, a polymer sample is subjected to a controlled temperature program in a specific atmosphere and properties are measured as a function of temperature. The controlled temperature program may involve either isothermal or linear rise or fall of temperature. The most common thermoanalytical techniques are (1) differential scanning analysis (DSC), (2) thermomechanical analysis (TMA), and (3) thermogravimetry (TG). 

Network properties and microscopic structures of various epoxy resins cross-linked by phenolic novolacs were investigated by Suzuki et al.97 Positron annihilation spectroscopy (PAS) was utilized to characterize intermolecular spacing of networks and the results were compared to bulk polymer properties. The lifetimes (t3) and intensities (/3) of the active species (positronium ions) correspond to volume and number of holes which constitute the free volume in the network. Networks cured with flexible epoxies had more holes throughout the temperature range, and the space increased with temperature increases. Glass transition temperatures and thermal expansion coefficients (a) were calculated from plots of t3 versus temperature. The Tgs and thermal expansion coefficients obtained from PAS were lower titan those obtained from thermomechanical analysis. These differences were attributed to micro-Brownian motions determined by PAS versus macroscopic polymer properties determined by thermomechanical analysis. 

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. 

Dynamic mechanical anlaysis (DMA) measurements were done on a Rheometrics RDS-7700 rheometer in torsional rectangular geometry mode using 60 x 12 x 3 mm samples at 0.05% strain and 1 Hz. Differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and thermogravimetric analysis (TGA) were performed on a Perkin-Elmer 7000 thermal analysis system. 

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