Reducing fire hazards and enhancing the thermal stability, acoustical, and UV protection of polyvinyl alcohol using bio-based flame retardant

Polyvinyl alcohol (PVA) is a highly flammable material, and enhancing its flame retardancy to pass the glow wire test is a great challenge. In this work, the melamine salt of tannic phosphate (MTP) was synthesized, characterized, and combined with PVA at 8, 10, 13, and 15 wt%. The thermogravimetric analysis (TGA) results indicated that MTP enhanced the char formation of PVA at 750°C. Flammability tests showed that low concentrations of MTP can enhance the flame retardancy of PVA. The limiting oxygen index (LOI) of PVA increased from 18.8% to 39.9% in the PVA/15%MTP composite. The vertical flame spread test (UL94V) showed that PVA/13%MTP, and PVA/15%MTP composites achieved V0 rating. Glow wire test data indicated that PVA/10%MTP, PVA/13%MTP, and PVA/15%MTP composites had a glow wire flammability index (GWFI) of 960°C/2 mm. Moreover, all the composites passed the needle flame test when the flame application time was 120 s. PVA/15%MTP composite showed very good UV protection and an increase in sound absorption coefficient magnitude compared with pure PVA. The new results can increase the application of PVA in different industries.