The Experts below are selected from a list of 12147 Experts worldwide ranked by ideXlab platform
Dagmar R Dhooge - One of the best experts on this subject based on the ideXlab platform.
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evaluating the exit pressure method for measurements of normal stress difference at high shear rates
Journal of Rheology, 2020Co-Authors: Dahang Tang, Flavio H Marchesini, Ludwig Cardon, Dagmar R DhoogeAbstract:A challenge for Polymer Rheology is the reliable determination of shear dependent first normal stress difference (N1 values) at high shear rates (>10 s−1). Here, we evaluate the correctness of the commonly applied exit pressure method focusing on polypropylene and high and low density polyethylene melts at 200 °C. It is demonstrated that the linear extrapolation of pressure values toward the die exit, which is a key step in the application of the exit pressure method, is affordable to determine N1 values despite that these extrapolated exit pressure values are characterized by a relative deviation of 25%–40%. The validity of the exit pressure method is further supported by an excellent match with rheological data from the Laun rule (exponent close to 0.7) and a representative simulation of extrudate swelling data in the width and height direction, considering tuned parameters for the Phan–Thien–Tanner constitutive model. Also, the absence of a significant viscous heating effect near the die exit is highlighted based on numerical analysis.
Dahang Tang - One of the best experts on this subject based on the ideXlab platform.
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evaluating the exit pressure method for measurements of normal stress difference at high shear rates
Journal of Rheology, 2020Co-Authors: Dahang Tang, Flavio H Marchesini, Ludwig Cardon, Dagmar R DhoogeAbstract:A challenge for Polymer Rheology is the reliable determination of shear dependent first normal stress difference (N1 values) at high shear rates (>10 s−1). Here, we evaluate the correctness of the commonly applied exit pressure method focusing on polypropylene and high and low density polyethylene melts at 200 °C. It is demonstrated that the linear extrapolation of pressure values toward the die exit, which is a key step in the application of the exit pressure method, is affordable to determine N1 values despite that these extrapolated exit pressure values are characterized by a relative deviation of 25%–40%. The validity of the exit pressure method is further supported by an excellent match with rheological data from the Laun rule (exponent close to 0.7) and a representative simulation of extrudate swelling data in the width and height direction, considering tuned parameters for the Phan–Thien–Tanner constitutive model. Also, the absence of a significant viscous heating effect near the die exit is highlighted based on numerical analysis.
Mark Price - One of the best experts on this subject based on the ideXlab platform.
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the effect of melt viscosity on thermal efficiency for single screw extrusion of hdpe
Chemical Engineering Research & Design, 2014Co-Authors: Javier Verasorroche, Adrian L Kelly, E C Brown, Tim Gough, Chamil Abeykoon, Phil D Coates, Jing Deng, Kang Li, Eileen Harkinjones, Mark PriceAbstract:Abstract In this work, a highly instrumented single screw extruder has been used to study the effect of Polymer Rheology on the thermal efficiency of the extrusion process. Three different molecular weight grades of high density polyethylene (HDPE) were extruded at a range of conditions. Three geometries of extruder screws were used at several set temperatures and screw rotation speeds. The extruder was equipped with real-time quantification of energy consumption; thermal dynamics of the process were examined using thermocouple grid sensors at the entrance to the die. Results showed that Polymer Rheology had a significant effect on process energy consumption and thermal homogeneity of the melt. Highest specific energy consumption and poorest homogeneity was observed for the highest viscosity grade of HDPE. Extruder screw geometry, set extrusion temperature and screw rotation speed were also found to have a direct effect on energy consumption and melt consistency. In particular, specific energy consumption was lower using a barrier flighted screw compared to single flighted screws at the same set conditions. These results highlight the complex nature of extrusion thermal dynamics and provide evidence that rheological properties of the Polymer can significantly influence the thermal efficiency of the process.
Flavio H Marchesini - One of the best experts on this subject based on the ideXlab platform.
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evaluating the exit pressure method for measurements of normal stress difference at high shear rates
Journal of Rheology, 2020Co-Authors: Dahang Tang, Flavio H Marchesini, Ludwig Cardon, Dagmar R DhoogeAbstract:A challenge for Polymer Rheology is the reliable determination of shear dependent first normal stress difference (N1 values) at high shear rates (>10 s−1). Here, we evaluate the correctness of the commonly applied exit pressure method focusing on polypropylene and high and low density polyethylene melts at 200 °C. It is demonstrated that the linear extrapolation of pressure values toward the die exit, which is a key step in the application of the exit pressure method, is affordable to determine N1 values despite that these extrapolated exit pressure values are characterized by a relative deviation of 25%–40%. The validity of the exit pressure method is further supported by an excellent match with rheological data from the Laun rule (exponent close to 0.7) and a representative simulation of extrudate swelling data in the width and height direction, considering tuned parameters for the Phan–Thien–Tanner constitutive model. Also, the absence of a significant viscous heating effect near the die exit is highlighted based on numerical analysis.
Ludwig Cardon - One of the best experts on this subject based on the ideXlab platform.
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evaluating the exit pressure method for measurements of normal stress difference at high shear rates
Journal of Rheology, 2020Co-Authors: Dahang Tang, Flavio H Marchesini, Ludwig Cardon, Dagmar R DhoogeAbstract:A challenge for Polymer Rheology is the reliable determination of shear dependent first normal stress difference (N1 values) at high shear rates (>10 s−1). Here, we evaluate the correctness of the commonly applied exit pressure method focusing on polypropylene and high and low density polyethylene melts at 200 °C. It is demonstrated that the linear extrapolation of pressure values toward the die exit, which is a key step in the application of the exit pressure method, is affordable to determine N1 values despite that these extrapolated exit pressure values are characterized by a relative deviation of 25%–40%. The validity of the exit pressure method is further supported by an excellent match with rheological data from the Laun rule (exponent close to 0.7) and a representative simulation of extrudate swelling data in the width and height direction, considering tuned parameters for the Phan–Thien–Tanner constitutive model. Also, the absence of a significant viscous heating effect near the die exit is highlighted based on numerical analysis.