COMBUSTION OF POLYETHYLENE FILLED WITH METALLIC HYDROXIDES AND CROSS-LINKABLE POLYETHYLENE

Incorporation of magnesium hydroxide and alumina trihydrate into polye thylene confers good fire retardancy together with excellent smoke sup pressant characteristics without evolution of toxic or corrosive decom position products originating from the filler phase. However, the tota l impact energies (E(t)) of the polymer decreased dramatically upon ad dition of these metallic hydroxide fillers. These limitations can be o vercome by adding silane crosslinkable polyethylene (SCPC) copolymer t o polyethylene/metallic hydroxide samples and/or treating the SCPC-con taining samples with boiling water, which gives a dramatic improvement in E(t), combined with further improvement in fire retardancy propert ies and smoke suppressant characteristics. Further investigations indi cated that the gel contents of SCPC-containing samples increased signi ficantly with the amounts of SCPC added and the treatment times in boi ling water. These results suggested that crosslinking of SCPC in polye thylene/metallic hydroxide samples can significantly improve the flame retardant, smoke suppressant and impact properties of these samples.