Preparation and Properties of Bio-Based Flame Retardant Polyvinyl Alcohol

Polyvinyl alcohol (PVA) has been widely used in the fields of medical, food and packaging due to its excellent biocompatibility, good fiber-forming and film-forming properties. However, the high flammability of PVA has greatly limited its wider applications. The flame-retardant PVA was prepared by melt blending of a bio-based flame retardant (prepared from lignin, phosphoric acid and carbamide) with thermoplastic PVA (TPVA). The chemical structure, morphology, thermal properties, mechanical properties, fire property and fluidity of this flame retardant PVA were investigated by Fourier transform infrared spectrometer(FTIR), field emission scanning electron microscope(SEM), thermogravimetric analyzer(TGA), impact tester, universal testing machine, horizontal-vertical burning tester, limiting oxygen indexer(LOI) and melt flow rate meter(MFR). The results showed that the prepared flame retardant had good compatibility with the PVA substrate; The impact strength, melt flow rate, fire property and char residue of this PVA material increased with the content of bio-based flame retardant. When the content of flame retardant was of 20%, the five indices including impact strength, melt flow rate, UL-94 level, LOI and char residual were 11.3 KJ/m2, 21.2 g/10 min, V-0 UL-94 level, 33.1%, and 19.2%, respectively. This research can promote the high-value utilization of lignin and the application of PVA in the fields of fire protection.