Moisture content of Aluminum Tri Hydrate (ATH)

Hi,

Be aware that ATH releases moisture at elevated temperatures!

2Al(OH)3 ---> Al2O3 + 3H2O

Al(OH)3 = ATH decomposes at about 200C and requies 1.05 kJ/g with the resultant loss of 34.6 wt% as water vapor.

So whatever your incoming moisture, avoid decomposition during storage/handling/processing! This consideration may be more important than test methods, etc. In some cases, the reason you are using ATH in the first place is so that it will act as a flame retardant. However, you'll also want to be sure that the ATH has been properly handled so that you are buying ATH and not Al2O3 or it won't work!

Choose flame retardants carefully. For instance, processing in polypropylene or nylons would reach temps that cause moisture to be released from ATH but not Mag Hydroxide.

Mg(OH)2 ---> MgO + H2O

Mg(OH)2 decomposes at about 350C and absorbs 1.3 kJ/g of heat with the resultant loss of 30.9 wt% as water vapor.

Ref: Mark E. Shand. Wiley. 2006. p180