Experimental study on pyrolysis gas products of chlorinated polyvinyl chloride and its smoke properties during combustion

The pyrolysis gas products of chlorinated polyvinyl chloride (CPVC) are first discussed based on thermogravimetry-Fourier transform infrared spectra-mass spectrometry (TG-FTIR-MS) analysis. The results of TG-FTIR preliminarily show that CPVC pyrolysis can be divided into two stages: the main gas products or functional groups are hydrogen chloride (HCl), chlorinated compounds, alkanes, alkenes and aromatic compounds in Stage I, while alkanes, aromatic compounds and alkenes in Stage II. By coupling MS, the main products can be further refined into hydrogen chloride and benzene in Stage I, while homologues, derivatives and polycyclic aromatic compounds of benzene (xylene and ethylbenzene, chlorobenzene and 1-chloronaphthalene, naphthalene and fluorene and so on) in Stage II. Moreover, compared with the pyrolysis gas products of PVC, chlorine is not completely converted into hydrogen chloride, and some of it is converted into other chlorinated compounds. Based on the above results, the possible reactions from molecular structure during CPVC pyrolysis are also put forward. Furthermore, the CPVC combustion properties and smoke production in cone calorimeter experiment are analyzed by the measured mass loss rate, heat release rate, smoke and CO/CO2 production rate.