On-line quality measurement of polymer extrusion is of great importance for process monitoring and product quality control. In view of the shortcomings of the existing hardware-based sensors, a low-cost capacitive transducer (CT) as an alternative hardware sensor has been designed for polymer extrusion. The entire research project will be presented in two aspects: the theoretical framework and the experimental implementation.

In the theoretical part, a detailed discussion on the sensitivity analysis is firstly performed on the proposed capacitive transducer, aimed to optimize the parameters of the transducer to better reflect the minor quality variations of the polymer extrudates before experiments are implemented. After that, theoretical capacitance calculation of the CT...[ Read more ]

On-line quality measurement of polymer extrusion is of great importance for process monitoring and product quality control. In view of the shortcomings of the existing hardware-based sensors, a low-cost capacitive transducer (CT) as an alternative hardware sensor has been designed for polymer extrusion. The entire research project will be presented in two aspects: the theoretical framework and the experimental implementation.

In the theoretical part, a detailed discussion on the sensitivity analysis is firstly performed on the proposed capacitive transducer, aimed to optimize the parameters of the transducer to better reflect the minor quality variations of the polymer extrudates before experiments are implemented. After that, theoretical capacitance calculation of the CT for both rectangular and circular section dielectrics are conducted as the basis of further experiments. Besides, the influence of changing measure conditions such as the measured target moving and rotating are specificly investigated in order to demonstrate the feasibility of the capacitive transducer in the real processing situations with non-contacting measurement.

In the experimental part, the developed capacitive transducer has been applied for thickness and diameter monitoring of polymer extrudates. Experiments with various polymer extrudates show that the proposed transducer features broader application and the output results are robust and effective. A new measure method using increased capacitance of the transducer as reference is proposed for thickness/diameter detection. In this way, the error factors are deducted effectively. The application of the capacitive transducer is also successfully expanded to online melt monitoring for component analysis of polymer blend extrusion.

It can be concluded that the developed low-cost capacitive transducer is capable for thickness/diameter prediction and also real-time melt monitoring of polymer extrusion. Therefore, this research paves the way for on-line closed-loop quality control of polymer extrusion.