Title: Rheological Characterization of Thermoplastic Polymers Using Melt Flow Index: Viscosity Modeling of LDPE and PP
Authors: Yousif.A A,Maysa.E.M. Mohamad H. H. Deifalla
Volume: 9
Issue: 9
Pages: 1-12
Publication Date: 2025/09/28
Abstract:
This work presents a rheological investigation of thermoplastic polymers using melt flow index (MFI) testing, focusing on low-density polyethylene (LDPE) and polypropylene (PP). Measurements of MFI and melt volume rate (MVR) were conducted at different temperatures and applied loads with a capillary plastometer. The experimental data were used to calculate shear stress, shear rate, viscosity, and mass flow. Results revealed that viscosity decreased with increasing temperature and MFI, confirming the pseudo plastic nature of both polymers. The rheological behavior was successfully modeled using the Power Law and Carreau models, with power-law indices (n) ranging between 0.58-0.61 for LDPE and 0.60-0.66 for PP. Activation energies were also determined, highlighting the thermal sensitivity of melt viscosity. Overall, the study demonstrates the effectiveness of MFI testing as a practical tool for correlating viscosity with processing parameters, providing valuable insights for optimizing thermoplastic polymer processing in industrial applications.