experimental investigation on morphological characteristics and stability of poly(vinyl chloride) microspheres by microsuspension polymerization

The synthesis of stable uniform nonporous poly(vinyl chloride) microsuspension with the unimodal narrow size distribution 0.1-1 µm and the volume-weighted mean diameter 0.18-0.22 µm was achieved using double-stage high-pressure homogenizer. the effect of homogenizer pressure and number of homogenization passes (or recycle time) on morphological characteristics and stability of microspheres have been investigated. the mean size and size distribution of the particles decreased by raising the pressure and number of passes and there is no any changes in the mean particle size in the periods of time up to 1 h. the sample at 20 mpa and 1 pass (15 min) has the best stability in the mean particle size and particle size distribution with high zeta potential -21 mv and low specific surface area 2.1e4 m2kg-1. in the samples at 40 mpa and 3 passes (45 min) in the periods of time, despite a little instability and the coalescence between the larger particles, the size distribution (d90 and d90/d10) enhanced and the mean d10 particle size and the zeta potential declined.