PVT Diagram

[Anonymous]

Dear All,

Although basic but I want to improve my knowledge about PVT Diagram of material. Can you please help me out for

1.How I can relate material PVT diagram with any of results or processing parameters?

2. In PVT diagram generally graph is given for 3 to 4 pressure values ,how I can predict which is better for my analysis.

Although very basic but I will be thankful if you are able to clear my doubt.

[Anonymous]

I am not sure that I fully understand your question but I will try to answer.

• PVT is one of the most important parameters for packing simulation. It predicts how the melt volume changes after pressure increases and temperature drops. Consequently it determines the amount of flow through the gates, pressure in the cavity and ultimately shrinkage and its distribution. 
  In the material data there are two density parameters: density of solid polymer and density of melt. Obviously, they are related to pVT:

       Rho_solid=1/V(p=0,T=T_room)

       Rho_melt= 1/V(p=0,T=Tmelt)

Ususlly, a little bit of discrepience in densities provided and calculated does not affect the result much.

Another, often overlloked thing is the correspondence between b5 and T_phase_transfer in semi-crystalline polymers. Both are related to the onset of crystallization. Usually b5 is 5..10 degrees below T_phase_transfer (the software automatically tries to correct unusual relations between those temperatures).

• The pVT parameters should reasonably approximate all density data for temperatures between T_room and Tmelt and pressure between 0 and the holding pressure. If there are problems with adequately fitting pVT parameters you better contact Autodesk Moldflow Lab, they have a good experience of it.