Discolouration of polypropylene-based compounds containing magnesium hydroxide

摘要

Magnesium hydroxide is extensively used in the plastics industry as a flame retardant and smoke suppressant in various poly- meric matrices (polyolefins, nylons etc.). However, it was found that compounding Mg(OH)_2 with polymers leads to the formation of various colours ranging form light grey to rather dark beige. The effect of the temperature and processing technology, and of various properties of Mg(OH)_2 (impurities, particle size and morphology) on colour formation was investigated in this work. One of the cause for the discolouration appears to be the interaction between the Mg(OH)_2 and antioxidants containing phenolic groups.