The influence of magnesium hydroxide and its coating on the mechanical and fire properties of glass-reinforced polyamide 66

The objective of the project was to develop halogen and phosphorous free flame retardant polyamide 66 composites using magnesium hydroxide, either alone or in admixtures. In common with alumina trihydrate (ATH), magnesium hydroxide has attracted considerable attention over the last twenty years, as a halogen and phosphorous free alternative for both thermoplastics and elastomers. However, owing to its greater thermal stability magnesium hydroxide can be added to thermoplastics (such as polyamide 66) which are melt processed at temperatures where alumina trihydrate is impractical due to premature degradation. There are problems however, using such a flame retardant system, due to the high filler loadings (~60 wt%) required to achieve adequate flame retardancy, which leads to detrimental effects on both processing and mechanical properties. [Continues]