Recent developments on on-line rheometry to monitor the extrusion process

On-line rheometers are generally inserted between extruder and die and generate data that is typically utilized for quality control purposes. However, on-line rheometers have also the potential to detect changes in structure, morphology, or composition of a given material system, thus assisting materials research and processing optimization, if they can be used along the axis of the extruder or compounder. The authors have previously developed on-line capillary and rotational/oscillatory rheometers that can be inserted and used at specific locations along the extruder. Since these devices are operated manually, their manipulation may be cumbersome and data may lack reliability. This work presents new versions of these rheometers, with improved functionalities and motorized operation. Details on the validation of one of them is also given. This study was carried out within the frame of the MULTIHYBRIDS IP 026685-2IP project, 6th Framework EC Program. The authors also gratefully acknowledge funding by FEDER via FCT, Fundação para a Ciência e Tecnologia, under the POCI 2010 and Plurianual programs.