Molecular Control Systems Ltd

The 50 year old problem

MFI is recognised as the Gold Standard in the polymer industry. It is used in the control of chain length within the reactor for the selling specification of virgin polymer and compounding. Up till now the ‘On-Line/At-line’ analyser has not been able to mirror MFI to ASTM D1238/ISO1133 standards. It is often quoted that ‘MFI is impossible to replicate’, which has resulted in a lack of confidence in the automated MFI measurement. The use of Automatic Process Control (APC) greatly eases this problem but in general the industry is saddled with a QA dependence on the manual MFI equipment. There is almost a complete lack of trustworthy control systems using MFI or rheology as the measured variable from ‘On-Line/At-line’ equipment. This has the effect of requiring highly trained plant operators to try to interpret complex information. This methodology carries a high risk as there are numerous areas that are interrelated and can easily be misinterpreted by the staff.

MCS R&D Project with the UK Department of Trade and Industry (DTI)

The DTI funding of this project has made it possible for Molecular Control Systems Ltd (MCS) to investigate and develop unique solutions to the ‘On-Line/At-line’ measurement of Melt Flow Index (MFI). The project brought together specialists from Fleming PTC together with Applied Computing and Engineering Ltd (ACEL) who contributed with their world leading Computer Fluid Dynamics (CFD) expertise. MCS provided specialist knowledge of ‘On-Line/At-line’ MFI measurement.

Successes of the project

• Identification/analysis of flow characteristics of the MFI system, using CFD
• Reproduction of actual MFI test conditions in the generic gear pump Rheometer
• Standardisation of rheology measurements to MFI
• Establishment of the ‘On-Line/At-line’ Melt Indexer as a plant worthy instrument