Kinetic study on the bulk polymerization of vinyl chloride at low temperature

A study has been made of the bulk polymerization of vinyl chloride at −50°C. using the tri‐ n ‐butyl boron‐oxygen system as initiator. The reaction is autocatalytic and the order of reaction with respect to tri‐ n ‐butylboron is 0.56. The apparent activation energy determined in the temperature range from −30 to −50°C. was 6.5 kcal. The kinetic results are discussed and from a comparison of here activation energy with that obtained in the range from +25 to −20°C., an interpretation is suggested for the previously observed abnormal behaviour of the molecular weights with the polymerization temperature.