Effect of Crystallization on Pressure-Volume-Temperature Relations

2 Effect of Crystallization on Pressure-Volume-Temperature Relations 

The specific volume v of a semi-crystalline polymer is a combination of the amorphous and crystalline structures. From the mass balance, one obtains 

Equation 4.31 is useful in simulations. Standard PVT data and the Tait equation can be used for calculation of at melt zone and at solid zone, while the specific volume at transition zone can be calculated using crystallization kinetics and a linear interpolation between 1/v and 1/v using Eq. 4.31. 

It should be noted that some authors (e.g., Luye et al. 2001) write the equation as V = (1 — a)v + av, where a is defined as a relative mass crystallinity (rather than the relative volumetric crystallinity as we have used) the expression is equivalent to Eq. 4.31. 

---