The Pyrolysis of Poly(vinyl chloride) Containing Sodium Carbonate or Sodium Hydrogencarbonate

ning sodium c bonate or sodium hydrogencarbonate were studied by meansof DTA, TG, X-ray diffraction and gas analyses.<BR>The following results are obtained<BR>1 Hydrogen chloride evolved from PVC easily reacted with sodium carbonate and sodiunt hydrogencarbenate at 200eC. The reaction of sodium carbonate or sodium hydrogencarbopate viith hydrogen chloride is expressed by Na2COs 2HCI=2NaCl H20 CO2. Sodium hydrogencareh changes into sodium carbonate at 200C which reacts with hydrogen. chloride, Sbdiuih hydrogencarbonate reacted with hydrogen chloride evolved from PVC more effectively than sodium carbonate.<BR>2 It was observed that fresh sodium carbenate which was produced by the re. action, 2N gCOs=NaaCOs + H20 + CO2, was very active. However, fresh sodium cqrboinate became less react ve ag ainsrmt PVC when sodium hydrogenearbonate was decomposed at higher tem. penafu fe than at 2-2 OC, or when it was aged, These facts may be interpreted in terms-of the a-e 6rease in both of the effective strain and the specific surface area of fresh sodium carbonatet<BR>3 The following table shows the lowest ignition temperature and the activation energy of igni tion for PVC alone and for PVC containing sodium carbonate. PVC a1 sodium 1 parts iiiff. iii6ffilElitioR teinp. ( ) 580 6Zg Arctivatien energy of ignition (kcal/mol) 12.3 12.1<BR>The activation energy showed no effect on the flame retardation. The result is ipterpr-e-te-g in rmtbrmr ms of the fact t h at sodium carbonate reacted with hydrogen ehloride evolved frgm nPVC W-hi 6hM retarded the fiame in the gaseous phase as other halides did. However, thei fla-mg to physical re-effect on the ignition temperature was observed. This fact attributed property of sodium chloride produced, <BR>4 fhe analysis of gaseous components in the thermal dgcopaposition of. PVC conta ning ethylene, ethane, sodfum carbonate revealed the facts that amount of both low hydrocarbons etc and aromatic compounds tended to decrease, and that a large-amount of carbon. dioxide evolved Evolution of them was caused by the reactien between sodium carbonate and hydro gen chleride evolved from PVC.