The m/z signals of volatile products evolution of XPS at different temperature regions are displayed in Figs. 5 to 8.
Linear chain product 1, 3-butadiene, which gives a strong m/z 54 signal, shows a two-stage release at 220-300 ºC and 350-
500 ºC in Fig. 5. As the MS results displayed in Fig. 6, signals at m/z 104, 103, 78, 51 and 77 are observed with high
intensity. Meanwhile, the No.2 peak which represents styrene monomers is also the maximum height of peak in gas
chromatogram. It reveals that styrene monomers are the dominant volatile gases in the range of 350-500 ºC. And
depolymerization reaction predominate the thermal degradation of XPS material at this stage. Methylbenzene and α-methyl
styrene [10] are also detected by GC-MS from about 370 ºC.