Table of Contents of THE GREAT MYTHS IN POLYMER RHEOLOGY, part II

The Great Myths of Rheology Part II Transient and Steady State Melt Deformation: the question of Melt Entanglement Stability by Jean-Pierre Ibar IPREM-Laboratoire de Physique et Chimie des Polymeres Universite de Pau et Pays de l’Adour, Pau. France TABLE OF CONTENTS ABSTRACT A. INTRODUCTION -Transient and Steady State Behavior -Step Strain Experiment in the non-linear Region -Step Strain Rate Experiment under non-linear Condiitons. -Strain Induced Transients under Oscillation Shear Mode -Combining Rotation and Oscillation Shear Modes. -The work of Osaki et al. -Effect of combining rotation and oscillation in the non-linear regime: Shear-Refinement under Dynamic Conditions -Combined Flow rates from Pressure Flow and Rotational Flow. -Combined Oscillation and Rotation. -Shear-Refinement: the Effect of Thermal-Mechanical History. -Melt Fracture. Edge Fracture in Parallel Plate Experiments -Objectives of this Article. B. EXPERIMENTAL PROCEDURE, POLYMER CHARACTERIZATION, DEFINITION OF PARAMETERS. 1. Experimental Procedures 1A The simple time sweep at given T, w and strain %. 1B The simple time sweep at given T, w and strain % immediately followed by a cooling ramp test performed in the linear range. 2. The three Step Experiments of Type FTF (Frequency-Time-Frequency) in a Dynamic Rheometer. 3. The four Step Experiment of Type FT1-FT2-FT1-FT2 in a Dynamic Rheometer. 4. Pure Viscometry. 5. Pure Viscometry followed by a Frequency Sweep. 6. Viscosity Measurement under Extrusion Flow Conditions. 7. In-line viscosity Measurement at the end of a "treatment Processor". 2. Rheometers Used. 3. Materials. 3.1 polycarbonate 3.2 polystyrene 3.3 LLDPE 4. Initial State and Sample Molding Procedure. 4.1 PC 4.2 LLDPE 4.3 PS 5. Definition of the Rheological Parameters to Analyse the Stability of Melt. C. RESULTS 1. Linear PC. Time Sweeps at various Temperatures, Frequencies, at 50% strain. 2. Viscometric Experiments on LLDPE 2.1 Pure Rotation Experiment of Type 4. 2.2 Pure Rotation followed by Frequency Sweep Experiment of Type 5 2.3 Experiments of Type 4 on Melts with Prior Therm-Mechanical History. 2.4 Transients created in Dynamic Conditions by Increase of Strain. 3. Dynamic Experiments of Type 2 (FS-TS-FS) on PC. 3.1 Effect of Strain at low Frequency (0.1 Hz). -3.1.1 5% strain -3.1.2 20% strain -3.1.3 500% strain -3.1.4 5% strain using a disentangled melt obtained by controlled shearrefinnemen 3.2 Effect of Frequency during Time Sweep (at constant strain of 5%). 3.2.1 1 Hz 3.2.2 10 Hz 3.2.3 40 Hz 3.3 Effect of Increasing Energy Input during Time Sweep: T=225 oC, Frequency= 5 Hz, and g=20% 3.4 Effect of Annealing the Melt after Treatment and Experiment of Type 3. 4. Long Term Entanglement Network Stability for a PMMA “disentangled” melt. 5. Entanglement Network Instability for a Polystyrene Melt. -5.1 PS-1 (PS1070) -5.2 PS-2: Thermal-Mechanical History to Create out-of-Equilibrium Melt Properties. D. DISCUSSION 1-The Question of the Origin of the Time Dependency of the Visco-Elastic Parameters. 2-Challenging Interpretations: 2.1 -viscous heating. 2.2 -Shear Degradation. 2.3 -Drooling of the Melt Outside of the Rheometer Plates. 2.4 -Plastification due to an increase of the monomer concentration by the shear process. 2.5 -Shear-Thinning. 2.6 -Edge Fracture Explanation: -Melt Fracture Initiation. Vinogradov's criteria -Simultaneous Dielectric and Dynamic Mechanical Measurements in the Molten State. 3-Effect of the Nature of the Surface Melt Contact. 4-Melt Flow Index of Disentangled Pellets and in-line Viscosity of Disentangled Melts. 5-Manifestation of Properties of Disentangled Polymers is not new. 6-The real problem is the understanding of the nature of entanglement and of the entropic character of polymer melt deformation. E. SUMMARY F. CONCLUSION G. ACKNOWLEDGEMENT H. REFERENCES