Spin Mode-Instabilities in Propagating Fronts of Polymerization

We have observed two instabilities in propagating fronts of methacrylic acid polymerization, both of which give the appearance of a spin mode. One occurs with liquid monomer when the tube is subjected to an external airflow to increase the rate of heat loss. It is novel instability caused by convection related to bubble formation. Spinning modes very similar to ones observed in solid-state combustion reactions were observed when the initial methacrylic acid/initiator solution was maintained at 0°C. The helical pattern left in the polymer and temperature profile measurements confirm for the first time the presence of a true spin mode in a constant velocity polymerization front