Chapter 5

CONTENTS 5.1 Introduction: Understanding Extrusion Foam Processsing................196 5.2 Tools for Understanding Foam Extrusion .............................................196

5.2.1 Introduction....................................................................................196 5.2.2 Solubility.........................................................................................197 5.2.3 Plasticization ..................................................................................198 5.2.4 Nucleation ......................................................................................199

5.3 The Ultrasonic Technique.........................................................................200 5.3.1 Basics: The Propagation of Sound Waves in Polymers ..........200 5.3.2 Off-Line Technique........................................................................201 5.3.3 In-Line Technique..........................................................................204