Abstract: Phosphited polyvinyl alcohol (P-PVA) was synthesized from diethyl phosphite and oxidated polyvinyl alcohol (O-PVA) which was obtained by oxidation of polyvinyl alcohol with KMnO₄. The structure of P-PVA was confirmed by FT-IR and ¹H NMR. Using P-PVA as the main component and polyaryl polymethylene isocyanate (PAPI) as curing agent, the flame-retarding properties of the prepared particle board were investigated to have a limiting oxygen index (LOI) of 27.9, when the loading of P-PU was 18%. Result of TGA showed that compared with normal polyurethane (PU) adhesive, P-PU adhesive can decrease the initial decomposition temperature which prolongs the stage of low-temperature dehydration-carbonization and increases the yield of residue char of wood particleboard at high temperature.

Key words: flame retardance, formaldehyde-free, polyurethane adhesive, wood particleboard