Capilary Rhoemetry Shear Sweep, Thermal Sweep

Capillary Rheometry Shear Sweep, Thermal Stability ASTM D3835, ISO 11443

Capillary Rheometry: Measuring Viscosity for Quality Control and Processing Optimization

In the manufacturing of plastic products, it is important to understand the viscosity or resistance to flow of the plastic material being used. This information is necessary for determining processing parameters, ensuring consistent quality from lot to lot, and identifying any processing degradation that may occur, leading to reduced physical properties. Capillary Rheometry is a commonly used method to measure apparent viscosity over a broad range of shear rates and at varied temperatures, which are comparable to the conditions encountered in molding, calendaring, extrusion, and other processing techniques.

Test Procedure: Capillary Rheometry involves melting the plastic material and extruding it through a capillary. The force required to push the material through the capillary is measured at different shear rates, and the viscosity is calculated using this data. The test can be conducted at different temperatures and other parameters, according to customer specifications. In a Shear Sweep, the shear stress and shear rate are calculated and plotted to provide a comprehensive view of the material's viscosity characteristics.

Thermal Stability: Capillary Rheometry is also useful in measuring thermal stability. To determine this, melted plastic is extruded through a capillary after being subjected to various residence times in the barrel of the extruder. The apparent melt viscosity is then calculated and plotted against residence time. This allows manufacturers to monitor processing conditions, identify any potential degradation of the plastic material, and adjust processing parameters as needed.

Specimen Size: For Capillary Rheometry, 80g of material is typically used. This amount is sufficient to obtain accurate and reliable data while also conserving materials.

Data: The data obtained from Capillary Rheometry includes measurements of apparent viscosity over a range of shear rates and temperatures. In a Shear Sweep, the shear stress and shear rate data are plotted to produce a comprehensive view of the material's viscosity characteristics. For Thermal Stability, the apparent melt viscosity is calculated and plotted against residence time. This data provides valuable insights into the behavior of the plastic material during processing, which can be used to optimize processing conditions and ensure consistent quality.

Equipment Used: Capillary Rheometry is typically conducted using specialized equipment known as a Capillary Rheometer. This machine applies controlled pressure to a molten sample of plastic and measures the force required to push the material through a capillary. The equipment is designed to operate over a range of temperatures and shear rates, allowing for a comprehensive analysis of the material's viscosity characteristics.

In our opinion, Capillary Rheometry is a powerful tool for manufacturers of plastic products, providing important insights into the material's viscosity characteristics, thermal stability, and other critical processing parameters. This information can be used to optimize processing conditions, ensure consistent quality, and identify any potential issues that could affect the physical properties of the final product.