17 - Rheology Control

Abstract

The melt flow rate is the measure of a polymer's ability to flow under certain conditions. It measures a melt flow rate, which is the amount of a polymer that flows over a period of time under specified conditions. High melt flow rate poly(propylene) can be produced directly in a polymerization reactor, but its production is often limited by the solubility of hydrogen in the reaction. Hydrogen is the most effective chain transfer agent for propylene polymerization reactions, whether the reaction takes place in solution or in the bulk monomer. Another method for producing high melt flow rate poly(propylene) is to degrade low melt flow rate poly(propylene) using controlled rheology. The controlled rheology treatments are often employed as alternative techniques for producing high melt flow rate poly(propylene) because these treatments do not depend on the hydrogen solubility. The controlled rheology treatments can also be used to increase production efficiency by converting the low melt flow rate polymers into high melt flow rate polymers without changing the reactors operating conditions. Thus, many manufacturers prefer controlled rheology treatments to produce high melt flow rate polymers. The technique for controlling the rheology of homopolymers and copolymers of poly(propylene) consists of peroxide degradation of these polymers. It is used to develop fluid products in an efficient way without having a detrimental effect in terms of production flow rates by reducing the number of basic polymerization powders.