Diagnostics of Extrusion Processes

Table of Contents

Preface

1 Rheological Properties of Molten Polymers

1.1 Polymer Melt Flow

1.1.1 Apparent Shear Rate

1.1.2 Apparent Viscosity

1.1.3 Power Law of Ostwald and de Waele

1.1.4 Viscosity Formula of Klein

1.1.5 Resin Characterization by Power Law Exponent

1.1.6 Melt Flow Index

1.2 Relationship between Flow Rate and Pressure Drop

1.3 Shear Rates for Extrusion Dies

2 Analytical Procedures for Troubleshooting Extrusion Screws

2.1 Three-Zone Screw

2.1.1 Extruder Output

2.1.2 Feed Zone

2.1.3 Metering Zone (Melt Zone)

2.1.4 Practical Evaluation of Screw Geometry

2.2 Melting of Solids as a Tool for Solving Screw Problems

2.2.1 Obtaining Better Melt Quality

3 Investigating Die Performance and Die Design by Computational Tools

3.1 Spider Dies

3.1.1 Pressure Drop along the Spider

3.2 Spiral Dies

3.2.1 Problem Solving by Simulating Shear Rate and Pressure

3.3 Adapting Die Design to Avoid Melt Fracture

3.3.1 Pelletizer Dies

3.3.2 Blow Molding Dies

3.3.3 Summary of the Die Design Procedures

3.4 Flat Dies

3.5 An Easily Applicable Method of Designing Screen Packs for Extruders

3.5.1 Mesh Size

3.5.2 Design Procedure

3.5.3 Influence of Polymer Type and Screen Blocking

4 Parametrical Studies

4.1 Blown Film

5 Design Software

5.1 Input and Output Data

5.1.1 VISRHEO

5.1.2 TEMPMELT

6 Thermal Properties of Solid and Molten Polymers

6.1 Specific Volume

6.2 Specific Heat

6.3 Thermal Expansion Coefficient

6.4 Enthalpy

6.5 Thermal Conductivity

6.6 Thermal Diffusivity

6.7 Coefficient of Heat Penetration

6.8 Heat Deflection Temperature

6.9 Vicat Softening Point

7 Heat Transfer in Plastics Processing

7.1 Case Study: Analyzing Air Gap Dynamics in Extrusion Coating by Means of Dimensional Analysis

7.1.1 Heat Transfer between the Film and the Surrounding Air

7.1.2 Chemical Kinetics

7.1.3 Evaluation of the Experiments

References

Index