Common Testing Methods

PVT (Pressure-Volume-Temperature) by Liquid Volume Displacement Testing is an advanced and time-consuming process used to characterize the volumetric properties of materials under varied temperature and pressure conditions.

This test measures:

  • Measures initial density at ambient conditions
  • Uses mercury as a confining fluid
  • Conducted under a range of temperatures and pressures
  • Generates a series of curves
  • Ensures a true hydrostatic state
pvT Test Data for Semi-Crystalline materials:
  • The transition region is critical
  • As temperature rises, specific volume increases as crystallinity breaks up.
  • As pressure rises, specific volume decreases relating to the Bulk Modulus.
pvT Test Data for Amorphous Material:
  • The transition temperature is not dependent on the mode of testing
pvT Testing for Fiber Filled and Neat Polymers:
  • LVDT testing is the most appropriate for fiber-filled composite polymers.
  • Unfilled polymers can be tested, alternatively, in a rheometer or other piston-styled apparatus.
  • The cooling rate will affect the shape of the resulting curves ("Fast Cooling" vs Standard Test)

Software and Data Management

  • The software used by the lab for genomic testing is not directly used by the end user.

  • Labs perform tests and provide the results, which are outside the control of the end user.

Interaction with Lab

It is important to know the type of test the lab is conducting. If there are issues with the data, contact the lab for clarification and review the test results with them.

Importing Coefficients

  • Importing coefficients is an alternative workflow focusing on the quality of the coefficients rather than the fit to the data. Further, fitting materials like Polyetherimide and some polymer alloys are not yet supported by the automated fitter in Material Modeler. If these are fit using another application, the coefficients can be imported using an Excel or CSV file containing the coefficients.
  • Important models such as Tait, IKV, and Schmidt require specific volume alignment between solid and molten states without significant discontinuity in phase change for the injection molding "Packing" solver to operate properly. Altair's injection molding solver will exit with an error if the discontinuity is too large.

Creating Inspire Mold Files

To create Inspire Mold files, Tait equation coefficients are needed. If the required coefficients are available, they will be used to create the Inspire Mold (XML) file for further use. Inspire Mold can import the file produced as long as it has all the required information.