Thermal pulse method

Test Method for Thermal Diffusivity of Carbon and Graphite by a Thermal Pulse Method... 

Bias-induced reverse piezoelectric response Broadband dielectric spectroscopy (BDS) Dielectric permittivity spectrum Dielectric resonance spectroscopy Elastic modulus Ferroelectrets Electrical breakdown Acoustic method Characterization Dynamic coefficient Interferometric method Pressure and frequency dependence of piezoelectric coefficient Profilometer Quasistatic piezoelectric coefficient Stress-strain curves Thermal stability of piezoelectricity Ferroelectric hysteresis Impedance spectroscopy Laser-induced pressure pulse Layer-structure model of ferroelectret Low-field dielectric spectroscopy Nonlinear dielectric spectroscopy Piezoelectrically generated pressure step technique (PPS) Pyroelectric current spectrum Pyroelectric microscopy Pyroelectricity Quasistatic method Scale transform method Scanning pyroelectric microscopy (SPEM) Thermal step teehnique Thermal wave technique Thermal-pulse method Weibull distribution... 

In contrast to the thermal wave technique, which operates in the frequency domain, the thermal-pulse method represents a transient technique operating in the time domain. This method was first described in 1975 (Collins 1975) and uses short light pulses of 10-100 ps duration as excitation signal. 

In addition to the above methods, other techniques based on the chaige oompensatioo method [3S23S3], the thermal pulse method (3S435S], polarization and depolarization current methods, etc. [256,257], have also been used by some workers in the field to study the characteristics of electrets. 

ASTM 0714-05(2010). Standard test method for thermal diffusivity of carbon and graphite by thermal pulse method. 

In the heat pulse method, the sample of heat capacity C is thermally linked to the thermal bath (at temperature rB) by a conductance G. 

R. Righini and A. Cezairliyan, Pulse Method of Thermal Diffusivity Measurements, A Review , High Temperatures-High Pressures, 5 481-501 (1973). 

Methods employing continuous irradiation consider the photochromic system as a dynamic system that is open to light flux energy. The kinetic equation of the photochemical reaction can thus be established. This equation is not taken into consideration in the pulsed methods as they study only the thermal relaxation process after the flash. 

The thermal conductivity values for polycrystalline (optically-thick) CaF obtained by. ngery —(comparative linear flow method) and by Taylor and Mills (laser pulse method) are in reasonable agreement (Figure 7). However, there is an appreciable discrepancy between the values of k obtained by the ziiQc source method —"— and the single value due to Ogino et al (radial heat source method). 

Laser pulsed methods have been used successfully for polyethylene, polycarbonate, polyimide, and polymethylmethacrylate typical film growth rates are 0.02-0.1 nm per laser pulse. As an alternative to traditional thermal evaporation or spin-coating, this method has also been used to deposit organic materials for organic electroluminescence... 

Besides pulse calorimetry, the laser flash (LF) technique is an established tool for directly measuring the thermal diffusivity by penetrating a sample with a short laser pulse on one side and monitoring the change in temperature on the opposite site. More details about pulse methods for diffusivity measurements can be found in, e.g., [72]. 

Thermal Diffusivity - The thermal diffusivity [D = k/(pCp)] of S10C-N312 BN 2-D composites was determined by the laser flash method in which a laser is used as a heat source and the thermal pulse transmission speed is measured in the desired orientation. Thermal diffusivity measurements were made both in-plane and through-plane ofthe 2-D composite. The specimen size was 9x9x2 mm square. The thermal diffusivity was calculated from solution of the diffusion equation for heat flow with the known boundary conditions. Details of this procedure are found in ASTM Standard Test Method E37.05 (Thermal Diffusivity by the Flash Method). 

The most extensive set of data for the elastic properties of europium was measured on polycrystalline material by Rosen (1968a) using an ultrasonic pulse method (10 MHz) thermal contraction corrections for acoustic path length were made. The temperature dependencies of the elastic moduli and theta are... 

In the early works, it was found that the pulse method could lead to the fastest heating of epoxy resins [98] and improve their mechanical properties [99]. For example, it was shown that a computer controlled pulsed microwave processing of epoxy systems that consisted of diglycidyl ether of bisphenol A (DER 332) and 4,4 -diaminodiphenyl sulfone (DOS) in a cavity operated in TM012 mode could be successfully applied to eliminate the exothermic temperature peak and maintain the same cure temperature at the end of the reaction [100]. The epoxy systems under pulsed microwave irradiation were cured faster, and it was possible to cure them at higher temperatures when compared with a continuous microwave or conventional thermal processing. 

Figure 6.6 Thermal measurement by laser pulse method, (a) Laser pulse on the sample, (b) Temperature response of back face of sample...

The fundamental relations for chromatographic methods are introduced in Chapter 5 for mass transfer studies. These can be modified to handle heat transfer problems. In fact, method of moment was used to determine thermal pulse response in packed beds of inert particles (Sagara, Schneider and Smith, 1970). From analogy between Eq. (8-22) without gad and Eq. (6-SS), the first absolute moment and the second central moment for thermal pulse in an inert bed are given as... 

Fig. 17 Three common thermal excitation schemes H (f) or T t) used in thermal wave techniques for the profiling of space charges (a) thermal wave method (LIMM), (b) heat pulse method, and (c) thermal step technique...

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