Study on the effects of flame retardants on the thermal decomposition of wood by TG–MS

The effect of three flame retardants, K 2 CO 3 , Na 2 SiO 3 ·9H 2 O, and Na 2 B 4 O 7 ·10H 2 O on the process and composition of volatile products of the thermal degradation of wood has been investigated by the thermogravimetric (TG), differential thermogravimetry (DTG), differential thermal analysis (DTA), and the synchronous thermogravimetry–mass spectrometry (TG–MS) analysis methods. The results showed that the ion current intensity and ion peak area of m / z = 18 and 44 MS signals were increased by the flame retardants but the ion peak area of m / z = 28 MS signal was decreased (except K 2 CO 3 ) at the meantime. What’s more, the ion current intensity and ion peak area of m / z = 60 and 68 MS signals were also decreased (except K 2 CO 3 ), which mean that Na 2 B 4 O 7 can significantly enhances the dehydration and inhibits the depolymerization of wood. Although K 2 CO 3 accelerates the dehydration reaction, it cannot inhibit the depolymerization reaction effectively, so the flame retardant efficiency of K 2 CO 3 is decreased with the higher concentration. The catalysis of dehydration reaction of Na 2 SiO 3 is the worst one.