ATH Dehydration A Quantitative Approach

Ashing of a sample of plastic (or a plastic-based composition) containing ATH can determine how much the ATH was dehydrated during the processing. 

Though aluminum trihydrate, AI2O3 3H2O, or [Al(OH)3]2, theoretically contains three water molecule, in reality it typically contains a slightly reduced amount of water. A direct analysis of eight commercial ATH samples resulted in only 2.86 water molecules on average per AI2O3 in ATH. 

This was determined as follows. Eight ATH samples were studied  

At more gentle temperature treatment, only a fraction of water—on average— can be lost. In other words, some ATH molecules will lose a water molecule, and some ATH molecules will not. Below is a brief chart showing how ash content of respective ATH samples would look like (Table 14.7). 

TABLE 14.7 An amount of ash (per cent) after temperature treatment (at 525°C for 24 h) of Aluminum Trihydrate (ATH) until constant weight. Theoretical data. 

---