Applications, thermal microscopy

Applications. Optical microscopy finds several important applications in filled systems, including observation of crystallization and formation of spherulites and phase morphology of polymer blends. " In the first case, important information can be obtained on the effect of filler on matrix crystallization. In polymer blends, fillers may affect phase separation or may be preferentially located in one phase, affecting many physical properties such as conductivity (both thermal and electrical) and mechanical performance. 

The objective of this chapter is to present to the reader the many facets of thermal microscopy. Information on the following topics will be presented the evolution of the technique, background theory, the role of thermal microscopy as a complementary technique, general experimental parameters, industrial applications, references, and vendor directories. 

In addition to the applications of HSM detailed earlier in this chapter, there is a great deal of work being conducted in other industrial laboratories using the many variations of thermal microscopy. 

The authors have attempted to present a state-of-the-technique perspective for HSM in which a wide variety of information regarding this technique has been collected. Although there are applications to industries that were not addressed, it was our intent to present to the reader as much of the available information on the technique that was available. It is our hope that this chapter on thermal microscopy enables other scientists to apply HSM to applications in their respective industries and solve new research, development, and manufacturing problems. 

The book opens with the first three chapters devoted to differential scanning calorimetry (DSC), the most commonly used thermal method. These chapters cover the principles, optimal use, and pharmaceutical applications of the method. Subsequent chapters explore modulated temperature DSC, thermogravimetric analysis, thermal microscopy, microcalorimetry, high sensitivity DSC, dynamic mechanical analysis, and thermally stimulated current, all of which have attracted great interest within the pharmaceutical field. Each chapter includes theoretical background, measurement optimization, and pharmaceutical applications. 

Fang J, Pilon L (2011) Scaling laws for thermal conductivity of crystalline nanoporous silicon based on molecular dynamics simulations. J Appl Phys 110 064305 Gesele G, Linsmeier J, Drach V, Fricke J, Arens-Fischer R (1997) Temperature-dependent thermal conductivity of porous silicon. J Phys D Appl Phys 30(21) 2911 Gomes S, David L, Lysenko V, Descamps A, Nychyporuk T, Raynaud M (2007) Application of scanning thermal microscopy for thermal conductivity measurements on meso-porous sihcon thin films. J Phys D Appl Phys 40 6677... 

Cathodoluminescence microscopy and spectroscopy techniques are powerful tools for analyzing the spatial uniformity of stresses in mismatched heterostructures, such as GaAs/Si and GaAs/InP. The stresses in such systems are due to the difference in thermal expansion coefficients between the epitaxial layer and the substrate. The presence of stress in the epitaxial layer leads to the modification of the band structure, and thus affects its electronic properties it also can cause the migration of dislocations, which may lead to the degradation of optoelectronic devices based on such mismatched heterostructures. This application employs low-temperature (preferably liquid-helium) CL microscopy and spectroscopy in conjunction with the known behavior of the optical transitions in the presence of stress to analyze the spatial uniformity of stress in GaAs epitaxial layers. This analysis can reveal,... 

Crosslinked low-density polyethylene foams with a closedcell structure were investigated using differential scanning calorimetry, scanning electron microscopy, density, and thermal expansion measurements. At room temperature, the coefficient of thermal expansion decreased as the density increased. This was attributed to the influence of gas expansion within the cells. At a given material density, the expansion increased as the cell size became smaller. At higher temperatures, the relationship between thermal expansion and density was more complex, due to physical transitions in the matrix polymer. Materials with high density and thick cell walls were concluded to be the best for low expansion applications. 16 refs. 

In terms of beam delivery, the DLW method is based on optical microscopy, confocal microscopy [4,6,13] and laser tweezers [14] (for reviews on laser tweezers see [ 15,16]). These techniques allow for a high spatial 3D resolution of a tightly focused laser beam with optical exposure of micrometric-sized volumes via linear and nonlinear absorption. In addition, mechanical and thermal forces can be exerted upon objects as small as 10 nm molecular dipolar alignment can be controlled by polarization of light in volumes of with submicrometric cross-sections. This circumstance widens the field of applications for laser nano- and microfabrication in liquid and solid materials [17-22]. 

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