Quantification of Polymer Fouling on Heat Transfer Surfaces During Synthesis

Abstract

During the synthesis and processing of polymers, a significant amount of polymer may be deposited on the heat transfer surfaces. This deposit is unwanted and is usually named fouling. This study deals with the fouling behavior of a vinyl acetate/vinyl ester copolymer during emulsion polymerization and compares this to fouling of an already reacted vinyl acetate/ethylene copolymer dispersion. Besides the state of polymerization, also the influence of the wall temperature is investigated. The experiments are performed on cooled and heated surfaces. The deposition process is quantified by the mass‐based fouling resistance, the height of the fouling layer, and the surface coverage using a digital microscope. It is found that the state of polymerization and the temperature gradient between wall and bulk exert a strong influence on the fouling behavior, especially on the structure of the fouling layer.

Reactor Fouling in Emulsion Polymerization

“…These results further highlight the differences with those reported in ref . However, there were substantial differences between the two systems.…”

“…Therefore, the increase in fouling observed in Figure was mainly attributed to the reduction of the T g . It is worth pointing out that these results are somehow in conflict with those in ref , because the mere presence of monomer in the polymer droplets led to a higher fouling, whereas in ref , the highest amount of fouling was observed with preformed latexes.…”

“…However, there were substantial differences between the two systems. In ref , tertbutyl hydroperoxide/ascorbic acid was used as initiator and a nonionic stabilizer (poly­(vinyl alcohol)) was used. In the present work, a mixture of anionic and nonionic surfactants and KPS was used.…”

“…Furthermore, the distribution of fouling in the reactor depended on the flow patterns . Fouling in an external heat exchanger during emulsion polymerization has been recently studied and the results compared with particulate fouling due to a preformed latex . It was reported that fouling increased with the temperature of the heat exchanger wall and that the amount of fouling was substantially higher for preformed latexes (particulate fouling) than in the presence of polymerization.…”

Fouling Pathways in Emulsion Polymerization Differentiated with a Quartz Crystal Microbalance (QCM) Integrated into the Reactor Wall

“…To be distinguished from particle fouling is reaction fouling. [13,15] Deposition of solid organic material at a hot wall may simply be the consequence of an increased polymerization rate. Particle fouling and reaction fouling can synergistically promote each other.…”