Flame retardancy of polymers

Bio-based gelatins were used to improve the compressive and flammability properties poly(vinyl alcohol)/montmorillonite (PVA/MMT) aerogels, fabricated using a simple and environmentally-friendly freeze-drying method. Due to the excellent compatibility and strong interfacial adhesion between PVA and gelatin, the compressive moduli of aerogels were enhanced dramatically with the incorporation of gelatin. PVA/MMT/porcine gelatin aerogels exhibit compressive modulus values as much as 12.4 MPa, nearly 300% that of the control PVA/MMT aerogel. The microstructure of the PVA/MMT/gelatin aerogels show a three-dimensional co-continuous network. Combustion testing demonstrated that with the addition of gelatin, the self-extinguishing time of aerogel was cut by half and the limiting oxygen index values increased to 28.5%. The peak heat release rate, obtained from cone calorimetry, also decreased with the incorporating of gelatin. Thermogravimetric analysis demonstrated that the gelatins slowed the sharp decomposition of PVA matrix polymer and increased the thermal stability of aerogels at the major decomposition stage of the composite aerogels. These results indicate that as a green bio-based material, gelatin could improve the mechanical properties as well as the properties of flame-retardancy simultaneously.