ISM equation of state and PVTx profile of polymer solutions

ABSTRACT

An analytical equation of state (EoS) has been previously employed to predict the volumetric profile of several molten polymers. The appearing temperature-dependent parameters in the EoS were determined using corresponding states correlations based on the molecular scaling constants, dispersive energy parameters between segments/monomers (ε) and segment diameter (σ). In this study, that EoS was extended to several copolymer melts for predicting their specific volumes and some mechanical coefficients. The ability of the EoS has been evaluated by comparing the results with 738 literature data points for the specific volumes of four copolymer melts over the temperature range from 422.35 to 506 K and pressures up to 200 MPa. The average absolute deviation (AAD) of the calculated specific volumes from literature data was found to be 1.12%. The EoS was also extended to predict PVTx behaviour of seven polymer solutions involving molecular solvents such as water, anisole, 1-octanol and propane by the use of some operating interaction parameter between polymer-solvent molecules. Our calculations on the PVTx profile of studied solutions predicted 1212 experimental data points over the pressure range within 0.1–50 MPa with the AAD equal to 0.96%.

KEYWORDS:

• Equation of state
• copolymer melts
• polymer solution
• volumetric profile

Acknowledgements

The author thanks the University of Hormozgan for the financial supports.

Disclosure statement

No potential conflict of interest was reported by the author.

Nomenclature and units

List of symbols

AAD Average absolute deviation (%)

k_B Boltzmann’s constant (J K⁻¹)

NPNumber of data points

PPressure (Pa)

T Absolute temperature (K)

V^S Specific molar volume (m³ mol⁻¹)

MMW Monomer molecular weight (g mol⁻¹)

R Universal gas constant (J mol⁻¹ K⁻¹)

B₂Second virial coefficient.(m³)

bCo-volume (m³)

αRepulsive contribution to pair potential function (m³)

N_A Avogadro’s number

Greek letters

ρMolar density (mol m⁻³)

σSegment diameter (nm)

εDispersive energy parameter (J)

σ*Pseudo-segment diameter (nm)

ε*Pseudo-dispersive energy parameter (J)

λ Free parameter

Superscripts

Cal Calculated values

Exp Experimental value

Supplemental material

Supplemental data for this article can be accessed here.