ABSTRACT
CONTENTS 4.1 Introduction ................................................................................................142
4.1.1 Historical Perspective ...................................................................142 4.1.2 Nomenclature.................................................................................145 4.1.3 General Requirements for Physical Foaming Agents .............146
4.2 Physical Blowing Agents..........................................................................147 4.2.1 Hydrocarbons ................................................................................148 4.2.2 Inert Gases......................................................................................149 4.2.3 Hydrofluorocarbons......................................................................154 4.2.4 Other PFAs .....................................................................................157 4.2.5 Blends of Physical Blowing Agents ...........................................159
