Porous thermal properties

Thermal property is another critical property for furnace slag. Because of their more porous structure, blast furnace slag aggregates have lower thermal conductivities than conventional aggregates. Their insulating value is of particular advantage in applications such as frost tapers (transition treatments in pavement subgrades between frost-susceptible and nonfrost-susceptible soils) or pavement base courses over frost-susceptible soils. 

B. Gawdzik and T. Matynia, Thermal properties of porous copolymers of 1,4-di(metha-cryloyloxymehyl)naphthalene with divinylbenzene, React. Polym. 5, 197-202 (1987). 

Polymerization of styrene in microemulsions has produced porous solid materials with interesting morphology and thermal properties. The morphology, porosity and thermal properties are affected by the type and concentration of surfactant and cosurfactant. The polymers obtained from anionic microemulsions exhibit Tg higher than normal polystyrene, whereas the polymers from nonionic microemulsions exhibit a lower Tg. This is due to the role of electrostatic interactions between the SDS ions and polystyrene. Transport properties of the polymers obtained from microemulsions were also determine. Gas phase permeability and diffusion coefficients of different gases in the polymers are reported. The polymers exhibit some ionic conductivity. 

Polymea mictocapsules containing 0,0-3,5,6-trichloro-2-pyridyl phosphorothioate (Dursban) were prepared by reacting a polyisocyanate and a poly amine and the factors affecting the formation of the microcapsule wall examined. The formation of polyurea was confirmed by FTIR spectroscopy, the thermal properties of the microcapsules were investigated by DSC and the morphology of the microcapsules detenninedby scanning electron microscopy. Optimum conditions for the formation of a thin surface l er and a porous matrix were established. 9 lefs. 

Heat transfer in a porous medium depends on the thermal properties of both the fluid and the solid. For porous media k , is the thermal conductivity of the medium (fluid and solid) in the... 

Buntebarth G. and J.R. Schopper, 1998. Experimental and Theoretical Investigations on the Influence of Fluids, Solids and Interactions between them on Thermal Properties of Porous Rocks. Phys. Chem. Earth. Vol. 23, No.9-10 pp 1141-1146. 

The rate of heat penetration through the char layer is in proportion to the thermal properties and porosity of the char (43,44) since the mode of heat transfer to the unreacted lignin/char interface is by ordinary conduction through the char rather than by electron bombardment. Thus the apparent rate of devolatilization as measured by weight loss kinetics is slower (k > 1-10 min ) than one might predict from electron pseudotemperatures in the gas plasma. After an initial period, these apparent devolatilization rates are consistent with rates for conduction in porous char (44,49). 

Wallapapan, K., Sweat, V.E., Diehl, K.C., and Engler, C.R., Thermal properties of porous foods, in Physical and Chemical Properties of Foods, Okos, M.R. (ed.), American Society of Agricultural Engineers, St. Joseph, MI, 1986, pp. 77-119. 

Nano-sized MgO particles with weU-crystaUized structures have been prepared by using spray pyrolysis method with solutions of citric acid [219]. The optimum concentration of citric acid was 0.4 M, in order to obtain micrometer-sized MgO particles. The function of citric acid in the spray solution was to alter the thermal properties of the solution and thus to control the morphologies of the particles. The micrometer-sized precursor particles with hollow porous structures which were... 

As stated earlier the porous nature of the films gives rise to poor mechanical properties. However, since the thermal properties show interesting behavior (for example the possible nucleating effect caused by the LC polymer) new blends were prepared by mechanically mixing in the melt and these were then investigated in terms of their morphology and the thermal behavior as discussed within the next section. 

Poly(aryl ether ketone)s show outstanding chemical resistance and thermal properties. They are virtually insoluble in all common solvents at room temperature. These properties make poly(aryl ether ketone)s attractive materials for porous membrane preparation. 

The incredibly low thermal conductivity of high porosity silicon is reviewed in two chapters of this handbook Thermal Properties of Porous Silicon and Thermal Isolation with Porous Silicon. It can be utilized in specific applications but also introduce challenges with many characterization techniques and processes. Particular care must be taken with characterization techniques that utilize high energy excitation in localized volumes. Examples include micro Raman spectroscopy. 

Halimaoui A, Campidelli Y, Larre A, Bensahel D (1995) Thermally induced modifications in the porous silicon properties. Phys Stat Sol B 190 35... 

One of the most important physical parameters of any material is its thermal conductivity (see handbook chapter Thermal Properties of Porous Silicon ). Bulk crystalline Si, the material that is widely used in today s electronics and sensors, shows moderate thermal conductivity at room temperature (Slack 1964). On the other hand, highly porous Si, which is a complex nanostructured Si material, composed of interconnected nanowires and nanocrystals, shows a much lower thermal conductivity than that of bulk crystalline Si, which depends strongly on its structure and morphology. The voids within the porous Si layer and the low dimensionality of the highly porous Si skeleton serve to inhibit thermal transport within the layer. 

Mesoporous silicon has tunable thermal properties that can be radically different from those of nonporous silicon. Published data on the major thermal constants and the techniques of measurement are reviewed and values compared to those of other materials. The combination of very low thermal conductivity and heat capacity of highly porous silicon has led to a number of specific applications that exploit these thermal properties. 

Typical experimental values of these thermal properties are listed in Table 1. Coexistence of low a and low C in PS is a very attractive feature as the thermal insulating material (see handbook chapter Thermal Isolation with Porous Silicon ). Most conventional materials do not meet this requirement Though silica, polymers, and rubbers have relatively low thermal conductivities, it is difficult to lower their C values. The exceptional one is silica aerogel powder and its mixture with carbon... 

Van Loon, W.K.P. Van Haneghem, I.A., and Schenk, J., New model for non-steady-state probe method to measure thermal properties of porous media, Int. J. Heat Mass Transfer. 32(8), 1473-1482 (1989). 

Tsamis C, Nassiopoulou AG, Tserepi A (2003) Thermal properties of suspended porous silicon micro-hotplates for sensor applications. Sens Actuators B 95 78—82... 

H. GIES / Synthesis, Crystallographic, and Thermal Properties of a New Porous Silica 283... 

SYNTHESIS, CRYSTALLOGRAPHIC, AND THERMAL PROPERTIES OF A NEW POROUS SILICA... 

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