Many polymers that are utilized in the plastic industry are hygroscopic; these include polyester and nylons. Intrinsic viscosity (IV) is frequently employed as the specification of numerous resin grades for these types of materials. Hygroscopic resin manufacturers must consistently make sure that the intrinsic viscosity of their materials are within the specification because of this.
Dynisco online rheometers can be installed easily in a number of extrusion lines during an extrusion process and are able to continuously measure the intrinsic viscosity parameters of the extrudates. This is carried out by utilizing a mathematical correlation between polymer’s intrinsic viscosity and its shear viscosity.
The below Figures demonstrate the online measurements of shear and intrinsic viscosity of polyethylene terephthalate resins (both under-dried and dried PET resins) during an extrusion process over time.
Image Credit: Dynisco
Image Credit: Dynisco
PET resins must be dried carefully prior to the process to minimize the amount of moisture content and stop any degradation throughout the process. Under-dried PET has residual moisture, which can lead the polymer to be degraded inside the extruder.
Predominantly, this reaction broadened the polymer's molecular weight distribution and/or decreased the polymer’s molecular weight leading to a decrease in its intrinsic and shear viscosity parameters. However, the online rheometer monitored intrinsic viscosity in accordance with the resin’s IV specification after undertaking the proper drying of PET.
As it helps to reduce the waste amount, ensure the quality of the regrinds, and increase the efficiency of their process, this feature of Dynisco online rheometers has mainly produced interest among PET recyclers.
Acknowledgments
Produced from materials originally authored by Azadeh Farahanchi, Rheological Scientist, Ph.D. from Dynisco
This information has been sourced, reviewed and adapted from materials provided by Dynisco.
For more information on this source, please visit Dynisco.