**5. Summaries**

This chapter provided an introduction to different measurements of polymer PVT properties and the application of polymer PVT data for injection molding. Different measurements of polymer PVT properties includes conventional measurements (piston-die technique and confining-fluid technique), some improved experimental techniques considering the effect of cooling rate, shear rate and pressure, on-line techniques using injection molding machine or extruders, etc. Several testing modes of operation were discussed, including: isothermal compression taken in order of increasing temperature, isothermal compression taken in order of decreasing temperature, isobaric heating and isobaric cooling. Almost all the PVT measurement apparatuses can be used in these several testing modes. For injection molding, polymer PVT data could be important in two areas: numerical simulation and process control. So the 2-domain Tait EOS which is used widely in injection molding was introduced in this chapter, then an example on numerical simulation using different PVT data was shown, at last the development of the control concepts based on the polymer PVT relationship was introduced.

From these different research fields, we can see that the PVT properties of polymers play the most important role in both numerical simulation and process control for injection molding. The knowledge on PVT properties of polymers could be the fundamental concepts for the engineers in injection molding.

### **6. Acknowledgments**

Some contents of this chapter originally appeared in the References. The author gratefully acknowledge the support of the National Natural Science Foundation of China (Grant No. 50973009), the Basic Research Fund of Beijing Institute of Technology (Project No. 3100012211108) and the InTech.
