Suppressing Coalescence and Improving Uniformity of Polymer Beads in Suspension Polymerization Using a Two-Stage Stirring Protocol

Abstract

In a typical suspension polymerization, both emulsification and polymerization occur simultaneously in a single-stirred vessel reactor using a constant stirring speed and stabilizer concentration. This work introduces a novel two-stage stirring protocol for improving the uniformity of polymer beads produced in suspension polymerization reactors . In the two-stage stirring protocol proposed, the polymerization stage was carried out at a reduced stirring speed. This policy, verified by mathematical modeling, led to the drops coalescence being suppressed, and as a result, the drops average size and size distribution being maintained in the course of polymerization. The particle size distribution narrowing was more significant if the emulsification stage was carried out at room temperature, the stabilizer concentration was low, and the difference between the stirring speeds used in the two stages was large. The two-stage stirring protocol was extended to include a two-stage stabilizer-addition protocol, which further improved the quality of the beads.

Preparation of halogen‐free flame‐retardant expandable polystyrene foam by suspension polymerization

“…With the increase in stirring rate, the amount of fine powder increases gradually, and the average particle size decreases at first and then increases. When the stirring rate is higher than 450 rpm, collision between beads increases and agglomeration occurs . Therefore, under the precondition of controlling the formation ratio of fine powder, choosing a stirring rate of 300 rpm or 350 rpm, the yield is 96.74 and 97.16%, respectively, and the average diameter of the composite beads is 0.94 mm and 0.92 mm, respectively.…”

Surface Microstructure Regulation of Porous Polymer Microspheres by Volume Contraction of Phase Separation Process in Traditional Suspension Polymerization System

“…In the P(GMA-St-EGDA) system (Route III), phase separation occurred earlier due to the poor compatibility between the monomer with the porogen. [31] At the same time, the monomer has poor swelling performance to the micelles, so the micelle is smaller. However, the T g was relatively moderate, which not only made it possible to form supporting framework, but also gave rise to the shrinkage of "Eggshell" and wrinkle deformation in Figure 4C.…”

“…The “Eggshell” could be supported by micelles, so the surface of the microspheres appeared a spherical convex structure. In the P(GMA‐St‐EGDA) system (Route III), phase separation occurred earlier due to the poor compatibility between the monomer with the porogen . At the same time, the monomer has poor swelling performance to the micelles, so the micelle is smaller.…”

Cross-linked polymer microparticles with tunable surface properties by the combination of suspension free radical copolymerization and Click chemistry

“…A better understanding of the rheological properties of NBSs and a deepened investigation of the role of involved contact forces requires the access to µPs having tailored chemical, physical and structural properties such as: size, size distribution, shape, stiffness, surface roughness and surface chemistry. Suspension (co)polymerization of functionalized (co)monomers is one of the most suitable and versatile heterogeneous polymerization methods for the elaboration of functional polymer µPs in the 10-1000 µm size range with easily tunable composition as well as dimensional, thermal, mechanical, bulk and surface properties [2,[18][19][20][21][22][23][24][25]. However, the scope in terms of chemical functionalities of this fast one-pot approach is limited to functionalities compatible with a radical polymerization process in aqueous dispersed media (i.e.…”