Sodium hydroxycarbonate

Small single crystals, such as those of potassium titanatc, are being used at an annual rate of over 10,000 tons for the reinforcement of nylon and other thermoplastics. These composites are replacing die-cast metals in many applications. Another microfiber, sodium hydroxycarbonate (Dawsonite), also improves the physical properties and flame resistance of many polymers. Many other single crystals, called whiskers, such as alumina, chromia, and boron carbide, have been used for making high-performance composites. 

Sodium zinc carbonate (SZC) Zinc hydroxycarbonate (ZHC) Malachite (MA)... 

Dawsonite is the mineral name for sodium aluminium hydroxycarbonate, NaAl(0H)2C03. It can be produced synthetically in microfibre form, and decomposes at about 300 °C with release of water and carbon dioxide. There has been significant interest in its use as a reinforcing flame-retardant filler but this seems to have waned recently, possibly due to possible toxicity concerns. More information on the material and its performance can be found in an article by Milewski [63]. 

Odnevall and Leygraf found that there is a structural resemblance between hydroxycarbonate, hydroxychloride, hydroxysulfate and sodium zinc chlorohydroxysulfate [24], since these compounds have layered structures with sheets of Zn in octahedral and tetrahedral coordination, with the main difference being the chemical content and bonding between the sheets. This structural resemblance may facilitate the transformation from one phase into another under appropriate environmental eonditions. 

Dawsonite (Aluminum Co. of America—Alcoa, U.S.), which is sodium aluminum hydroxycarbonate, NaAl(0H)2C03, and is synthetically manufactured in acicular form. It improves tensile and flexural strengths and moduli, increases the heat deflection temperature, and lowers the coefficient of thermal expansion of composites of PE, rigid PVC, and ABS resins. Dawsonite decomposes at 300-320°C giving off CO2 and H2O, so it functions also as a flame retardant. 

In 1989, the concept of ethoxylating methyl esters, which do not carry a labile hydrogen, was introduced by Hoechts [2] and Henkel [3]. Hoechst demonstrated the ethoxylation of esters was chemically feasible using catalysts based on alkali and alkaline earth metals (e.g., sodium hydroxide, sodium methoxide, barium hydroxide, etc.). Henkel demonstrated the feasibility of using calcined hydrotalcite (aluminum-magnesium hydroxycarbon-ates) for the reaction. Reactivities and conversions with these catalysts, however, were found to be too low for commercial application. 

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