Fire performance of high-density polyethylene sheets protected by a coating of plasticized polyvinyl chloride/modified-vermiculite

Treatment of Palabora vermiculite with ammonium chloride or ammonium nitrate solutions caused the collapse of its structure, resulting in a reduction of the exfoliation onset temperature by more than 200°C. It is speculated that ammonium ions enter the hydrobiotite galleries as guest ions partially replacing the hydration water associated with the magnesium ions. The effectiveness of various modified vermiculite flakes as flame-retardant fillers was evaluated in laminates of high-density polyethylene and plasticized polyvinyl chloride/vermiculite-modified composites. The laminates comprised a high-density polyethylene sheet coated with polyvinyl chloride plasticized with 100 phr of a phosphate ester and filled with 40 phr vermiculite. Cone calorimetry results, measured at a radiant flux of 35 kW m −2 , revealed that copper-ion modified vermiculite was the most effective flame-retardant additive. Laminates coated with polyvinyl chloride containing copper-ion-modified vermiculite exhibited a significantly reduced peak heat release rate of 64kW/m 2 , compared to 677kW/m 2 for uncoated high-density polyethylene, demonstrating the potential of polyvinyl chloride–based flame-retardant coatings incorporating copper-ion-modified vermiculite for polyethylene.