(289e) Modeling and Control of End-User Polymer Properties in Gas-Phase Polymerization Reactors

Historically, polyolefin resins are produced according to some intermediate product specifications, for example, target density and melt index for polyethylene. The polymerization reactor is manipulated using inference models and feedback of the measurements. However, end users often require properties such as dart impact, tear strength, and Young's modulus, etc. that are not directly targeted by the intermediate product specifications. When the resin manufacturer's specifications and end-user's specifications are not consistent, it could lead to the generation of unwanted resins, a lack of customer satisfaction, and relatively-low level of plant utilization, etc. In this work, a method was developed to control polymer end-user properties via direct control of the manufacturing process. At first, a direct link between the end-user needs and polymer microstructures, such as copolymer composition, molecular weight and its distribution, is established.. Then the link between the polymer microstructures and polymerization reactor operation is developed. The development is conducted through the use of specific models and control methods which allow the production of polymer resins to the end-user specifications without the additional costly and/or time consuming in-situ measurement of end-user properties . Through examples of this work, it is demonstrated that the method is particularly important in the manufacture of multi-modal polyolefin resins where additional degrees of manufacturing freedom exist to match end-user desires.