Photoacoustic detection of phase transitions

Florian, R.; Pelzl, J.; Rosenberg, M.; Vargas, H.; Wernhardt, R.

doi:10.1002/pssa.2210480145

Cited by 76 publications

(11 citation statements)

References 6 publications

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“…With temperature modulated calorimetry (TMC) like third harmonic detection [14,15], photoacoustic methods (PA) [16], light heating DSC [17] or temperature modulated DSC (TMDSC) [18,19] frequency dependent heat capacity can be determined in the temperature range of the meta-stable equilibrium in the supercooled state. With these methods it is possible to perform heat capacity spectroscopy.…”

Section: Differential Scanning Calorimetry (Dsc)mentioning

confidence: 99%

Separation of components of different molecular mobility by calorimetry, dynamic mechanical and dielectric spectroscopy

Schick

Dobbertin

Pötter

et al. 1997

Journal of Thermal Analysis

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The relaxation strength at the glass transition for semi-crystalline polymers observed by different experimental methods shows significant deviations from a simple two-phase model. Introduction of a rigid amorphous fraction, which is non-crystalline but does not participate in the glass transition, allows a description of the relaxation behavior of such systems. The question arises when does this amorphous material vitrify. Our measurements on PET identify no separate glass transition and no devitrification over a broad temperature range. Measurements on a low molecular weight compound which partly crystallizes supports the idea that vitrification of the rigid amorphous material occurs during formation of crystallites. The reason for vitrification is the immobilization of co-operative motions due to the fixation of parts of the molecules in the crystailites. Local movements ([$-relaxation) are only slightly influenced by the crystallites and occur in the whole non-crystalline fraction.

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Section: Differential Scanning Calorimetry (Dsc)mentioning

confidence: 99%

Separation of components of different molecular mobility by calorimetry, dynamic mechanical and dielectric spectroscopy

Schick

Dobbertin

Pötter

et al. 1997

Journal of Thermal Analysis

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“…Heat deposited by a laser beam in a sample can increase the temperature of the sample, as discussed in the paragraph on thermal diffusivity above, or, if the sample undergoes a first order phase transition, provide the latent heat of that transition without changing the temperature at all. This well-known phenomena was first observed in the context of photoacoustics by Florian, et al (44). Anomalies in the amplitude and the phase of the observed signal (45)(46)(47) were interpreted (48) as a n oscillation of the liquid-solid phase boundary in the sample during the periodic illumination.…”

Section: (9)mentioning

confidence: 80%

Photothermal methods for the measurement of thermal properties of thin polymer films

Coufal

1991

Polymer Engineering & Sci

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The absorption of radiation in a sample gives rise to local heating. With a suitable modulated or pulsed source of radiation, a spatially well defined instantaneous heat source can be readily implemented. Radiation induced thermal transients are, therefore, the ideal heat sources for studies of thermal processes in thin films. Application of this method for measurements of thermal diffusivity and temperature dependent properties of thin polymer films are discussed. Imaging of inhomogeneities and depth profiling are another important area of application for these techniques. A number of applications emphasizing the various photoacoustic and photothermal techniques, their advantages and drawbacks are covered in detail.

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“…Latent heats of melting are responsible for discontinuities in the FD or TD signals. Florian et al [96] studied Ga melting, and so did Kojima [97] who produced images of the spatial variation of PA amplitude in the vicinity of the liquid-solid transition temperature [98]. Imhof et al [99] used PPTR to monitor the melting transition of benzophenone at 48 ~ This technique demonstrated the potential for studying re-crystallization dynamics during pulsed laser annealing and other surface treatments.…”

Section: Non-conventional Photothermal Applications To Thermal Amentioning

confidence: 99%

Photothermal applications to the thermal analysis of solids

Mandelis

1991

Journal of Thermal Analysis

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Major application of optically-induced thermal waves to the thermal and thermodynamic analysis of solids are reviewed. The spectrum of available techniques,from the conventional photoaeoustic detection to novel photothermal laser probing and frequency multiplexing is discussed, and their utilization for the measurement of thermophysical thermal transport-related parameters of solids is presented. These include the thermal diffusivity, effusivity, conductivity and specific heat. The ability of photothermal methods to perform thermal analysis on large classes of solids, including conducting and insulating bulk materials, crystals, layered porous and coated structures, thin films and inhomogeneous thermal profiles is highlighted. Finally, special capabilities of photothermal analysis, such as the monitoring of surface thermodynamic phenomena and phase transition studies, including high-Tc superconductors, are described in order to give a complete overview of the rich potential of photothermal-based methodologies.Exposure of a sample to radiation results in local heating due to absorption and subsequent thermalization of the incident radiation. The extent of absorption and the thermalized volume fraction depend on the interplay between the absorption profile and the thermal transport properties of the material under investigation. If the irradianee of the incident radiation is modulated harmonically or pulsed, an oscillatory or transient heat source, respectively, is generated in the sample. Thermal waves are thus created,

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Photoacoustic detection of phase transitions

Cited by 76 publications

References 6 publications

Separation of components of different molecular mobility by calorimetry, dynamic mechanical and dielectric spectroscopy

Separation of components of different molecular mobility by calorimetry, dynamic mechanical and dielectric spectroscopy

Photothermal methods for the measurement of thermal properties of thin polymer films

Photothermal applications to the thermal analysis of solids

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