Heating methods hotplate

Dissolution was accomplished by the method of Langmyhr and Pans (30). Each finely ground sample ( 100 mg) was transferred to an open 250 mL PTFE beaker, and 5 mL of 40% (v/v) hydrofluoric acid added, followed by 0.5 mL of perchloric acid. This mixture was taken to dryness on an electric hotplate and cooled. A further 5 mL of 40% hydrofluoric acid and 0.5 mL of perchloric acid were added, and the mixture again taken to dryness. The beaker was cooled, and 10 mL of 0.1 M hydrochloric acid was added. The salts were then brought into solution by heating. The clear solution was cooled and made up to 100 mL by the addition of distilled water to a polythene volumetric flask. Lanthanum... 

Both methods for decomposing the sample matrix require heat and both have benefited from replacement of resistive heating (e.g., laboratory hotplate equipment) with microwave heating (89). 

There are different methods to measure the thermal resistance of a fabric. The most widely used is the sweating guarded hotplate according to ISO 11092 (1993) and consists of a metal plate heated to 35 °C (approximately the skin temperature) (Figure 9.2). 

ASTM C177, Standard test method for steady state heat flow measurements and thermal transition properties by means of the guarded hotplate apparatus, 2004. 

There are various different methods used in the determination of thermal properties of textile fabrics, including both steady state heat transfer method and nonsteady state (or transient) heat transfer methods. The typical steady state heat transfer methods include guarded hotplate method, Togmeter, and SGHP the typical... 

For a flat slab specimen of thickness h (m), the thermal conductivity X (W m K ) is the heat flux per unit of temperature gradient in the direction perpendicular to an isothermal surface and is a material constant defined by the one-dimensional Fourier equation X = Qh/A(Ti — Tq) where Q is the time rate of the heat flow (W), A the area (m ) on a selected isothermal surface, and T and T2 the temperatures of the hot and cold surfaces, respectively, and h the sample thickness (m). Several steady-state or transient methods are available to measure the thermal conductivity of organic and inorganic materials." The guarded-hotplate (ASTM F433), heat-flow (ASTM C518), and Colora ther-moconductometer methods are accurate for thick plastic samples with thermal conductivity of 0.1—10 W m K . In electronics, steady-state techniques... 

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