A facile preparation of environmentally-benign and flame-retardant coating on wood by comprising polysilicate and boric acid

Abstract For the sake of direct using on the built wooden buildings, a green flame resistance coating comprising sodium polysilicate (SPS) and boric acid was prepared. With weight gain of only 10 wt.%, the treated wood sample (SPS/B-wood) performed improved limiting oxygen index value of 40.3% and passed the V-0 rating in UL-94 test. Additionally, the total heat release, total smoke production and peak carbon monoxide production of SPS/B-wood sample were decreased by 24.5%, 36.0% and 59.4% respectively, compared with that of control wood sample. The residue of SPS/B-wood sample was increased to 54.0% from 18.4% of control wood sample at 800oC in the thermogravimetry analysis. The flame retardant mechanism was suggested that SPS and boric acid formed Si-O-B and Si-O-Si contained structures, isolating the heat and smoke transfer during wood combustion. Notably, NaOH, introduced by the SPS/B coating, catalyzed the lignin to form compact and high-quality char. To conclude, this low-cost and easily-operated coating has a promising future utilizing in the villages with dense wood buildings.