Meaning
A mathematical constitutive equation describes the flow behavior of polymer melts and concentrated solutions by accounting for the non-linear elasticity of the material. Utilizing the phan-thien-tanner model allows simulation software to predict how polymers behave during processing steps that involve complex flow paths, such as die extrusion or film blowing. This model is particularly effective at capturing the tension-thinning behavior that other models ignore, making it essential for accurate design of processing equipment that handles high-viscosity resins.
Viscoelastic Calculation
The calculation represents the relationship between the stress tensor and the rate of deformation in a flowing polymer. In applying the phan-thien-tanner model, researchers adjust parameters related to the rate of molecular chain disentanglement under stress. These parameters are calibrated using data from shear and extensional rheology tests to ensure that the simulation matches physical reality.
This calculation is vital for predicting the occurrence of flow instabilities.
Stress Analysis
Extruding plastic through complex dies generates localized high-stress areas that can cause structural defects in the extruded product. High stress levels predicted by the phan-thien-tanner model indicate where the polymer molecules are being stretched beyond their limits. This analysis helps mold designers modify flow channel geometries to reduce shear and prevent premature material failure.
Melt Evaluation
Testing new polymer formulations requires verifying how they will behave under processing conditions before committing to full-scale production runs. The phan-thien-tanner model allows engineers to run virtual extrusion trials to compare different resin formulations. This virtual evaluation reduces the need for expensive physical trials and accelerates the development of new materials, which reduces the cost of scaling up new processes.
