Smoke-suppression in plasticised chlorinated poly(vinyl chloride) (CPVC)

摘要

A study has been carried out on the pyrolysis (in air) of plasticised chlorinated poly(vinyl chloride) (CPVC) using pyrolysis/gas chromatography/mass spectroscopy. CPVC plasticised with dioctyl phthalate (DOP) containing modest amounts of the smoke- suppressant, basic iron(III) oxide (FeOOH), produces small amounts of smoke when it is forced to burn in the air. It has been shown that the activity of the smoke-suppressing compound in this polymer system changes the decomposition path of the phtha- late plasticiser. In the absence of the smoke-suppressant, the major decomposition products are hydrogen chloride, benzene and a chlorinated hydrocarbon. When small amounts of the iron compound are incorporated into the polymer no benzene was detected amongst the decomposition products, only hydrogen chloride, phthalic anhydride (the major product) and the same chlorinated hydrocarbon were found. Hence the major source of smoke in this system (benzene) has been essentially removed by the chemical action of the smoke-suppressant. A scheme showing how the iron compound reacts with the polymer and plasticiser is proposed.