Investigation of the effects of nonisothermal suspension polymerization of vinyl chloride on resin properties

Molecular and morphological properties of suspension poly(vinyl chloride) produced by nonisothermal polymerization was experimentally investigated in a pilot-scale reactor. Although molecular weight and polydispersity index of the nonisothermally produced poly(vinyl chloride) is almost the same as the equivalent isothermal polymerization, there are differences in morphological characteristics. The cold plasticizer absorption of the resin produced nonisothermally is greater than that of the equivalent isothermal product. Scanning electron microscopy showed that nonisothermally produced particles are more regularly shaped, with a smoother surface, and had greater porosity compared with the product of isothermal polymerization reaction. Applying temperature trajectory produces particles with slightly wider particle size distribution relative to the particles produced isothermally. The evolution of particles with conversion is characterized by processing images obtained by scanning electron microscope. Applying a variable temperature trajectory accelerates the formation of a three-dimensional skeleton of primary particles relative to the isothermally produced particles. J. VINYL ADDIT. TECHNOL., 23:267-274, 2017. (c) 2015 Society of Plastics Engineers