The effects of magnesium hydroxide on flash pyrolysis of polystyrene

Pure polystyrene (PS) and flame-retarded PS composite containing magnesium hydroxide (Mg(OH)2) were pyrolyzed in a off-line furnace-type pyrolyzer at 700 °C for 10 min. The liquid and tar products were collected by Cambridge pad. The qualitative and quantitative analyses were carried out by gas chromatography/mass spectrometry (GC/MS). The results indicate that the effects of Mg(OH)2 on flash pyrolysis of PS are quite significant. The existence of Mg(OH)2 does not lead to the appearance of new products, but the results of quantitative analysis show that the product distribution of the PS/Mg(OH)2 sample is rather different from that of the pure PS sample. Almost all the relative intensities of products, especially some head-to-head structures and some condensed aromatic compounds, take on increasing tendencies except that of styrene monomer markedly decreases. The reasons of the changes were discussed from the aspect of reaction pathways and mechanisms.