Online measurement of rheological properties of polypropylene based on an injection molding machine to simulate the injection-molding process
(826-832) Polymer Testing 30 #8 (2011)
Gou et al of the Beijing University of Chemical Technology, China, developed test equipment based on an injection molding machine to measure the rheological properties under certain processing conditions.  The rheological properties of a semicrystal-line polymer, polypropylene, were measured using this novel mold under normal processing conditions, and the data were correlated by the Cross-WLF viscosity model. The differences in the rheological properties between online group and other techniques were observed.  Numerical simulations of injection-molding processes were carried out by Mold-flow software with online and offline data of rheological properties for polypropylene.  Improvements in the accurate prediction of warpage and shrinkage performance with input of online rheological data are presented compared to the offline ones.  (RDC 9/9/2011)

In-line rheo-polarimetry: A method to measure in real time the flow birefringence during polymer extrusion
(848-855) Polymer Testing 30 #8 (2011)
Soares, Santos and Canevarolo, Brazil, developed a new optical detection system, an in-line rheo-polarimeter, to measure in real time polymer flow birefringence during extrusion.  The total transmitted cross polarized light intensity is measured, converted into optical path difference, which is corrected for the transparent glass windows stress birefringence and then converted into the polymer flow birefringence in real time.  To validate the in-line measurements, a bench assessment was done using cast sheets of polycarbonate with known optical path difference as standards. The flow birefringence of polystyrene was measured in-line during the extrusion process, attaining values up to −4 × 10−4, close to those found in the literature. The flow birefringence of various polystyrene samples was measured in-line during the extrusion showing the effect of increasing molecular weight on the polymer chain orientation.  (RDC 9/9/2011)