Non Isothermal Tube Model Characterization for High Speed Thermoforming Stretch
Accurate non isothermal tube characterization reduces thermoforming wall variance to under six percent at hundred hertz stretch rates.
Pom Pom Polymer Model
Meaning
Mathematical simulation of branched polymer flows requires constitutive equations that capture the unique stretching and relaxation behavior of branched molecules. Applying the pom pom polymer model allows rheologists to predict the shear and extensional behavior of low-density polyethylene in complex processing geometries. This model approximates a branched molecule as a central backbone with multiple arms attached to each end.
Deformation Behavior
Branched polymers exhibit a strong strain-hardening effect when stretched, which is a defining factor in processes like film blowing. The pom pom polymer model captures this behavior by separating the relaxation times of the backbone from those of the side arms. This division allows the model to predict how the polymer melt behaves under rapid deformation without overestimating the stretching forces.
Simulation Accuracy
Flow instabilities like melt fracture or draw resonance can be predicted by simulating the extrusion process using appropriate rheological models. Integrating the pom pom polymer model into flow simulation software gives die designers a tool to analyze the flow profiles of highly branched resins. This simulation prevents the creation of die geometries that generate excessive shear stress, which would otherwise result in surface defects.
By adjusting the die angles based on these model predictions, engineers can design tooling that operates smoothly at higher output rates without triggering the onset of melt fracture.
Process Control
Resin producers use molecular models to design polymers with optimal processing characteristics for film or blow molding applications. High correlation between the pom pom polymer model predictions and actual extrusion trial data helps compounders refine the branching structure of new resin grades. This capability reduces the reliance on physical trial runs, helping manufacturers develop better-performing polymers more efficiently.