Magnesium hydroxide properties

Properties. The physical properties of magnesium hydroxide are Hsted in Table 8. The crystalline form of magnesium hydroxide is uniaxial hexagonal platelets (Fig. 4). Magnesium hydroxide begins to decompose thermally above 350°C, and the last traces of water are driven off at higher temperatures to yield magnesia. 

Chemica.1 Properties. The reactivity of magnesium hydroxide is measured primarily by specific surface area in units of /g and median particle size in p.m. Reactivity ranges from low, 1-2 /g, 5 p.m, eg, Kyowa s product to high, 60-80 /g, 5—25 pm, eg, Barcroft s CPS and CPS-UF... 

Bulk density is 1.49 kg/L for 57% solids slurry with a Mg(OH)2 loading of 0.85 kg/L. The properties of some magnesium hydroxide slurries are given in Table 12. 

Table 13. Properties of Commercial-Grade Magnesium Hydroxide Powders...

Carbon dioxide and calcium carbonate The effect of carbon dioxide is closely linked with the bicarbonate content. Normal carbonates are rarely found in natural waters but sodium bicarbonate is found in some underground supplies. Calcium bicarbonate is the most important, but magnesium bicarbonate may be present in smaller quantities in general, it may be regarded as having properties similar to those of the calcium compound except that on decomposition by heat it deposits magnesium hydroxide whereas calcium bicarbonate precipitates the carbonate. 

Magnesium hydroxide slurry, 75 403, 407 properties of, 75 404t viscosity of, 75 405-406 Magnesium iodide, 75 407-409 physical properties of, 75 408t Magnesium iodide dietherate, 75 408 Magnesium ions soap and, 22 724 sources for, 75 328... 

Simple Models. The surface chemical properties of clay minerals may often be interpreted in terms of the surface chemistry of the structural components, that is, sheets of tetrahedral silica, octahedral aluminum oxide (gibbsite) or magnesium hydroxide (brucite). In the discrete site model, the cation exchange framework, held together by lattice or interlayer attraction forces, exposes fixed charges as anionic sites. 

Plate-like particles of interest in this context include mica, aluminum flake, hammered glass, magnesium hydroxide and talc. Physical properties of composites containing these additives depend strongly on the flow-induced morphology and on the distribution of residual stresses [31]. 

The viscoelastic properties of polypropylene melts containing magnesium hydroxide fire retardant fillers have been studied using parallel plate dynamic rheology [36]. In this work the filler variants differed in particle size, surface area and morphology, ranging from approximately spherical particles formed... 

Watson, G.L. (1987) A study of the fire and mechanical properties of polypropylenes filled with sea water magnesium hydroxide, PhD thesis, Brunei University, UK... 

The traditional flame retardant is based on organobromine compounds together with antimony trioxide as a synergist. Magnesium hydroxide is a good flame retardant due to its high decomposition temperature and smoke suppression properties. It is widely used in thermoplastic materials. However, magnesium hydroxide must be added in portions of some 60% to achieve a reasonable effect. 

S. Chang, T. Xie, and G. Yang, Effects of polystyrene-encapsulated magnesium hydroxide on rheological and flame-retarding properties of HIPS composites, Polym. Degrad. Stab., 91(12) 3266-3273, December 2006. 

Choudhary V. R. and Pandit, M. Y. Surface properties of magnesium oxide obtained from magnesium hydroxide - influence on preparation and calcination conditions of magnesium-hydroxide. Appl. Catal., 1991, 71, 265-274. 

Montenzin, F. Lopez-Cuesta, J. M. Crespy, A. Georlette, P. Flame retardant and mechanical properties of a copolymer PP/PE containing brominated compounds/antimony trioxide blends and magnesium hydroxide or talc, Fire and Materials, 1997, 21(6), 245-252. 

Hydroxides, hydroxy carbonates, and hydrates of aluminum, calcium, and magnesium that potentially meet these requirements are shown in Table 7.1, together with relevant thermal properties and gaseous products evolved on decomposition. However, of those in commercial use, aluminum hydroxide makes up about 90% of the market by tonnage, with magnesium hydroxide and basic magnesium carbonate products being used in niche applications. 

Many variations of these processes exist with the aim of controlling particle surface area, shape, and purity these characteristics define the fire retarding performance of magnesium hydroxide fillers, especially in more demanding applications where processability and good mechanical properties are also important considerations. In more recent developments, nanosize magnesium hydroxide variants have also been produced. 

A more recent innovation has been the development of nickel-doped forms of magnesium hydroxide, which are claimed to have superior fire-retardant properties.4... 

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