Investigating the reduction of the time of suspension polymerization of vinyl chloride monomer using a mixture of initiators containing cobalt catalyst

In this study, the possibility of increasing the productivity of batch reactors for the polymerization of vinyl chloride using cobalt catalyst was investigated. This method led to a 33% reduction in polymerization time and the production of a product with K-values equal to the product of polyvinyl chloride polymer (PVC). Under the conditions of using cobalt catalyst, the reaction rate was higher at the beginning of the reaction and gradually decreased at the end of the reaction. The experimental and simulated profiles were run in a 15-liter reactor and the product properties were measured. The effect of the cobalt catalyst on properties such as particle size distribution of PVC powder, porosity of powder, apparent density, shape and structure of internal and external shell of particles and average molecular weight was investigated. Measurements of molecular weight distribution show that the average molecular weight and dispersion index, despite having the same K-values, are not affected by the conditions under which the cobalt catalyst is used. The absorption percentage of the softener increases. SEM images show that under cobalt catalyst conditions, more spherical and porous particles are produced, which is the reason that the three-dimensional aggregation of the particles occurs faster, which leads to more porosity inside the particles. The effect of using a cobalt catalyst on the thermal stability of polyvinyl chloride product was investigated according to DSC and TGA analysis, which causes a slight decrease in stability, but the amount of decrease does not cause a disturbance in the downstream processes