Study of thermal decomposition of poly(vinyl chloride) type polymers with the use of model substances—III: Gas phase pyrolysis of acetates

The decompositions of the following poly(vinylacetate) models were investigated in the gas phase: 2-acetoxypentane (in the range 323–380°), meso and racem. 2,4-diacetoxypentane (325–375°), 4-acetoxy-1-pentene (302–375°), 4-acetoxy-2-pentene (314–381°), 5-acetoxy-2-hexene (328–391°), and 7-acetoxy-3,5-nonadiene (299–361°). The decompositions are homogeneous unimolecular first-order reactions with rate constants of 1·04 × 10¹³ exp(?45·/RT, 1·63 × 10¹³ exp(?45·4/RT), 1·01 × 10¹³ exp(?44·5/RT), 5sd76 × 10¹² exp(?42·8/RT), 2·01 × 10¹³ exp(?45·5/RT), and 3·29 × 10¹² exp(?41·5/RT) sec^?1, respectively. The two 2,4-diacetoxypentane stereoisomers decompose at almost the same rate. From the course of decomposition of models in the gas phase, possible conclusions about decomposition of polymer are drawn. The role of configuration of sequences, double bonds, their number and geometric isomerism in the macromolecular chains are discussed in connection with elimination of acetic acid from poly(vinyl acetate).