Efficient flame retardant polyvinyl alcohol membrane through surface graft method

The preparation of flame retardant polyvinyl alcohol (PVA) membranes with high performance is a challenge using conventional methods by physically mixing flame retardants with a PVA solution. In this study, the surface grafting of a flame retardant on neat PVA membrane was adopted instead of conventional physical mixing. The structure and grafting ratio of the flame retardant grafted chemically on a PVA membrane was examined and characterized. A comparison of the performance between the surface grafted and the conventional mixed flame retardant PVA membranes were conducted by cone calorimetry, vertical flame, thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), mechanical properties and transparency tests. The results showed that with the same flame retardant content, the one with the surface grafted had much better flame retardance, mechanical properties and transparence, as well as an enhanced melt point and thermal stability. In conclusion, the surface grafting of the flame retardant PVA membrane is very promising for many applications due to its remarkably improved properties.