Preparation of vermiculite with phosphonium salt (P-VMT): In an aqueous suspension of VMT at 50 1C under stirring, 10 g was dispersed in 1000 ml of distilled water and then a solution of 5 wt% C16H36PBr was added dropwise, after which the mixture was heated to 70 1C and maintained at that temperature for 4 h. The suspension was washed with deionized water until no pre- cipitate of halide (bromide ion) was observed, upon titrating the filtrate with 0.1mol/L AgNO3. Finally, the P-VMT was vacuum dried at 60 1C for 72 h and sieved through a 200-mesh screen.
Mixing procedure: Composites were prepared in an Polylab Haake OS internal chamber mixer equipped with roller rotors, at a speed of 100 rpm and temperature or 140 1C for 8 min. Table 1 shows the mixtures studied. Before mixing, Ecobras was dried in a vacuum oven at 80 1C for 24 h.