Abstract
The authors are studying on the problems of utilizatiOn of Mg compounds obtained from bitter brine,such as basic magnesium carbonate,magnesium hydroxide and oxide,to the rubber industry.
This report is concerned with electron microscopic studies on (1) 4 kinds of common basic magnesium carbonates in market used as fillér of rubber,(2) effects of.its preparing conditions, that is, reaction temperature,concentration and crushing method,(3) manner of its decomposition to MgO and (4) magnesium hydroxide.
As results,(1) the transparency of basic magnesium carbonate and its specific volume may be influenced a little by the gathering state of its micro particles.(2) Common basic magnesium carbonate used as the filler of rubber nowadays,is always irregular thin micro particles of about 40mμ in tbikness and under 1μ in diameter.(Fig. A, B, C, D, M)
(3) Ip case of preparing the precipitate of basic magnesium carbonate from Na2CO3 and MgCl2, usually at first it appears gelatinous state as seen in Fig. E, then according to subsequent temperature, it grows to the needle crystals up to about 60°C, and over this temperature obtained the amorphous particles.
Such thin particles as common products can be obtained only by decomposition of needle crystal. We succeeded to find out the condition finmaking high quality product. Furthermore variable decomposition states of basic magnesium carbonate to MgO are shown in Fig. M-Q. At last,for comparison the thin micro particles of Mg(OH)2 are shown in Fig. R.
