Density miscellaneous materials

Miscellaneous Properties. The acoustical properties of polymers are altered considerably by their fabrication into a ceUular stmcture. Sound transmission is altered only slightly because it depends predominandy on the density of the barrier (in this case, the polymer phase). CeUular polymers by themselves are, therefore, very poor materials for reducing sound transmission. They are, however, quite effective in absorbing sound waves of certain frequencies (150) materials with open ceUs on the surface are particulady effective. The combination of other advantageous physical properties with fair acoustical properties has led to the use of several different types of plastic foams in sound-absorbing constmctions (215,216). The sound absorption of a number of ceUular polymers has been reported (21,150,215,217). 

Today polyether foam with a density of less than half that of rubber latex foam is widely used as a cushioning material. Polyester foams, although tending to be more expensive, continue to have a number of outlets, particularly where a high initial modulus is desirable. In addition to miscellaneous upholstery applications... 

The solubility of DDT in twenty materials—ketones, petroleum fractions, and several miscellaneous solvents—over the temperature range —30° to 76° F. was determined by the rapid density method developed by Mauke and Sheard. DDT was found to be most soluble in cyclohexanone and less soluble in aromatic petroleum fractions, but the solvent cost per unit of DDT dissolved with them was only one half that for cyclohexanone. Cyclic ketones were better solvents than acyclic ketones with the same number of carbon atoms and the solubility in ketones was found to decrease with increasing molecular weight. 

Miscellaneous. Phenolic foam has highly effective energy-absorption characteristics, and possible applications are now being studied. Low-density foams are also being studied for use as packaging materials. Meantime, when phenolic foam is carbonized at an elevated temperature under inert atmospheric conditions, cellular carbon can be produced. Cellular carbon may be used as a refractory insulating material. 

Gradient-forming materials which provide the densities required for the separation of subcellular particles include salts of alkali metals (e.g. caesium and rubidium chloride), small neutral hydrophilic organic molecules (e.g. sucrose), hydrophilic macromolecules (e.g. proteins and polysaccharides), and a number of miscellaneous compounds more recently introduced and not included in the above group, such as colloidal silica (e.g. Percoll) and non-ionic iodinated aromatic compounds (e.g. Metrizamide, Nycodenz and Renograffin). 

Miscellaneous applications of poly(phosphazenes) include ter-butoxycarbonyl protected materials for chemically amplified resists in microlithographythin film electroluminescent devices,optical wave guides, aryloxy derivatives as components of fire-, heat- and impact-resistant materials and components of a low-density, thermoplastic elastomeric, ablative insulation for rocket motors. ... 

Thermal conductivity values for ceramics, refractory oxides, and miscellaneous insulating materials are given here. The thermal conductivity refers to samples with density indicated in the second column. Since most of these materials are highly variable, the values should only be considered as a rough guide. 

This table gives the range of density for miscellaneous solid materials vifhose characteristics depend on the source or method of preparation. 

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