CARL HANSER VERLAG. Chris Rauwendaal. Polymer Extrusion

Transcription

1 CARL HANSER VERLAG Chris Rauwendaal Polymer Extrusion

2 Contents Preface to the Fourth Edition Preface to the First Edition vii ix 1 Introduction Basic Process Scope of the Book General Literature Survey History of Polymer Extrusion References Part I Extrusion Machinery 2 Different Types of Extruders The Single Screw Extruder Basic Operation Vented Extruders Rubber Extruders The Multiscrew Extruder The Twin Screw Extruder The Multiscrew Extruder with More Than Two Screws The Gear Pump Extruder Disk Extruders Viscous Drag Disk Extruders The Elastic Melt Extruder Overview of Disk Extruders Ram Extruders Single Ram Extruders Multi Ram Extruder Appendix References Extruder Hardware Extruder Drive AC Motor Drive System DC Motor Drive System Hydraulic Drive System Comparison of Various Drive Systems Reducer Constant Torque Characteristics Thrust Bearing Assembly Barrel and Feed Throat Feed Hopper Extruder Screw Die Assembly Screens and Screen Changers

3 xii Contents 3.7 Heating and Cooling Systems Electric Heating Fluid Heating Extruder Cooling Screw Heating and Cooling References Instrumentation and Control Instrumentation Requirements Most Important Parameters Pressure Measurement The Importance of Melt Pressure Different Types of Pressure Transducers Mechanical Considerations Specifications Comparisons of Different Transducers Temperature Measurement Methods of Temperature Measurement Barrel Temperature Measurement Stock Temperature Measurement Other Measurements Power Measurement Rotational Speed Extrudate Thickness Extrudate Surface Conditions Temperature Control On-Off Control Proportional Control Controllers Time-Temperature Characteristics Tuning of the Controller Parameters Total Process Control True Total Extrusion Process Control References Part II Process Analysis 5 Fundamental Principles Balance Equations The Mass Balance Equation The Momentum Balance Equation The Energy Balance Equation Basic Thermodynamics Rubber Elasticity Strain Induced Crystallization Heat Transfer Conductive Heat Transfer Convective Heat Transfer Dimensionless Numbers

4 Contents xiii Viscous Heat Generation Radiative Heat Transport Basics of Devolatilization Devolatilization of Particular Polymer Devolatilization of Polymer Melts Appendix References Important Polymer Properties Properties of Bulk Materials Bulk Density Coefficient of Friction Particle Size and Shape Other Properties Melt Flow Properties Basic Definitions Power Law Fluid Other Fluid Models Effect of Temperature and Pressure Viscoelastic Behavior Measurement of Flow Properties Thermal Properties Thermal Conductivity Specific Volume and Morphology Specific Heat and Heat of Fusion Specific Enthalpy Thermal Diffusivity Melting Point Induction Time Thermal Characterization Polymer Property Summary References Functional Process Analysis Basic Screw Geometry Solids Conveying Gravity Induced Solids Conveying Drag Induced Solids Conveying Plasticating Theoretical Model of Contiguous Solids Melting Other Melting Models Power Consumption in the Melting Zone Computer Simulation Dispersed Solids Melting Melt Conveying Newtonian Fluids Power Law Fluids Non-Isothermal Analysis Die Forming Velocity and Temperature Profiles

5 xiv Contents Extrudate Swell Die Flow Instabilities Devolatilization Mixing Mixing in Screw Extruders Static Mixing Devices Dispersive Mixing Backmixing Appendix Appendix Appendix References Part III Practical Applications 8 Extruder Screw Design Mechanical Considerations Torsional Strength of the Screw Root Strength of the Screw Flight Lateral Deflection of the Screw Optimization for Output Optimizing for Melt Conveying Optimizing for Plasticating Optimizing for Solids Conveying Optimizing for Power Consumption Optimum Helix Angle Effect of Flight Clearance Effect of Flight Width Single Flighted Extruder Screws The Standard Extruder Screw Modifications of the Standard Extruder Screw Devolatilizing Extruder Screws Functional Design Considerations Various Vented Extruder Screw Designs Vent Port Configuration Multi-Flighted Extruder Screws The Conventional Multi-Flighted Extruder Screws Barrier Flight Extruder Screws Mixing Screws Dispersive Mixing Elements Distributive Mixing Elements Scale-Up Common Scale-Up Factors Scale-Up for Heat Transfer Scale-Up for Mixing Comparison of Various Scale-Up Methods Rebuilding Worn Screws and Barrels Application of Hardfacing Materials Rebuilding of Extruder Barrels References

6 Contents xv 9 Die Design Basic Considerations Balancing the Die by Adjusting the Land Length Balancing by Channel Height Other Methods of Die Balancing Film and Sheet Dies Flow Adjustment in Sheet and Film Dies The Horseshoe Die Pipe and Tubing Dies Tooling Design for Tubing Blown Film Dies The Spiral Mandrel Geometry Effect of Die Geometry on Flow Distribution Summary Spiral Mandrel Die Design Variables Profile Extrusion Dies Coextrusion Interface Distortion Calibrators References Twin Screw Extruders Introduction Twin versus Single Screw Extruder Intermeshing Co-Rotating Extruders Closely Intermeshing Extruders Self-Wiping Extruders Intermeshing Counter-Rotating Extruders Non-Intermeshing Twin Screw Extruders Coaxial Twin Screw Extruder Devolatilization in Twin Screw Extruders Commercial Twin Screw Extruders Screw Design Issues for Co-Rotating Twin Screw Extruders Scale-Up in Co-Rotating Twin Screw Extruders Overview Twin Screw Extruders References Troubleshooting Extruders Requirements for Efficient Troubleshooting Instrumentation Understanding of the Extrusion Process Collect and Analyze Historical Data (Timeline) Team Building Condition of the Equipment Information on the Feed Stock Tools for Troubleshooting Temperature Measurement Devices Data Acquisition Systems (DAS) Light Microscopy Thermochromic Materials Thermal Analysis Miscellaneous Tools

7 xvi Contents 11.3 Systematic Troubleshooting Upsets versus Development Problems Machine Related Problems Polymer Degradation Extrusion Instabilities Air Entrapment Gel Problems Die Flow Problems References Modeling and Simulation of the Extrusion Process Paul J. Gramann, Bruce A. Davis, and Tim A. Osswald 12.1 Introduction Background Analytical Techniques Numerical Methods Remeshing Techniques in Moving Boundary Problems Rheology Simulating 3-D Flows with 2-D Models Simulating Flows in Internal Batch Mixers with 2-D Models Simulating Flows in Extrusion with 2-D Models Simulating Flows in Extrusion Dies with 2-D Models Three-Dimensional Simulation Simulating Flows in the Banbury Mixer with 3-Dimensional Models Simulating Flows in Extrusion Dies with 3-Dimensional Models Simulating Flows in Extrusion with 3-Dimensional Models Static Mixers Conclusions References Index