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.

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

In standard cone calorimeter test fire response properties like time to ignition, peak mass loss rate, time to peak mass loss rate, average mass loss rate and burn out time are of interest. The ASTM 1354 [1] recommends sample thickness of less than 50 mm for the test. However, for thinner samples conditions on the unexposed side of the sample should represent actual conditions in real-life application as the test results may be affected by these conditions. Therefore, in this work, a numerical study is carried out to predict the effect of sample thickness on the fire response parameters of polymeric materials. Polymeric materials are broadly classified as charring (thermoset) and non-charring (thermos-plastic). A representative material in each category, namely CPVC (Chlorinated Polyvinyl Chloride) for charring polymer and PMMA (Poly Methyl Metha-Acrylate) for non-charring is studied. It was noted that properties like the peak mass loss rate, time to peak mass loss rate, average mass loss rate and time to ignition vary with sample thickness for both charring and non-charring polymer. These property values become constant for sample thicknesses beyond a certain value. The variation in properties is dependent on the condition on the backside of the sample. When an aluminium block was assumed to have been placed below the sample, the property variation was different from when an adiabatic condition was assumed. The fire response properties for charring and non-charring materials also exhibited different trends.

Numerical Study on Sample Thickness Dependence of Fire Response Properties of Polymeric Materials (Charring and Non-charring) in Standard Cone Calorimeter Test

S. Sabarilal

Papers

Numerical Study on Sample Thickness Dependence of Fire Response Properties of Polymeric Materials (Charring and Non-charring) in Standard Cone Calorimeter Test

Effect of Back Boundary Condition on Pyrolysis of Charring and Non-charring Materials