ABSTRACT
Poly(ethylene terephthalate) (PET) foams show good mechanical properties, high temperature dimensional stability, and recyclability and have recently attracted extensive attention in academic and industrial circles. The wide applications of PET foams depend on cell morphology and matrix properties. Microcellular PETs with cell sizes less than 5 μm were developed by Furukawa Electric (Japan), and possessed the excellent property of over 99% reflectivity and 96% light diffusion rate, which increased lamps’ illuminance by 40%–60% without an extra light source as the reflector. Low-density PET foams with a cell size of hundreds of microns have been widely used as packaging materials and structure materials in wind energy, marine, and transportation applications. Supercritical CO2 has been used as a blowing agent for PET because it is inexpensive, nontoxic, and environmentally benign. CO2 dissolved into a PET matrix causes many changes in the physical properties of PET in both the melt and solid states due to the strong plasticization effect, which enhances the free
CONTENTS
3.1 Introduction .................................................................................................. 49 3.2 Controllable Sandwich Structure of PET Microcellular Foams
Based on the Coupling of CO2 Diffusion and Its Induced Crystallization .............................................................................................. 51
3.3 Melt Foamability of Reactive Extrusion-Modified PET ......................... 57 3.4 Melt-Foaming Behavior of In-Situ Modified PET in Batch
and Continuous Processes ..........................................................................65 3.5 Integrated Process of Supercritical CO2-Assisted Modification
and Foaming of PET .................................................................................... 73 3.6 Summary and Outlook ............................................................................... 78 Acknowledgments ................................................................................................ 81 References ............................................................................................................... 81
volume and chain mobility. It depresses the glass-transition temperature and the crystallization temperature, and changes the crystallization kinetics of semicrystalline PET, which may provide many opportunities for the manipulation of foaming processes.
