Determination of Some Thermodynamic Parameters of Poly(Styrene‐Graft‐Ethyl Methacrylate) Using Inverse Gas Chromatography

Abstract

In this study, the specific retention volumes, V_g ^o, were determined for poly(styrene‐g‐ethly methacrylate) obtained from grafting of poly(styrene‐co‐p‐chloromethyl styrene) having a 54% (by mole) chlorine content with ethyl methacrylate and a series of nonsolvent as probe, five n‐alkans, five alcohols and carbon tetrachloride, with the aid of inverse gas chromatography, in a temperature range of 333 to 463 K. Some thermodynamic properties, such as the sorption enthalpy, ΔH^s, sorption free energy, ΔG^s, sorption entropy, ΔS^s, in the 373–403 K temperature range, the partial molar free energy, ΔG^∞, and the partial molar heat of mixing, ΔH^∞, in the temperature 413‐463 K range, were calculated from the relationships between the specific retention volumes and related properties. The weight fraction activity coefficients of probes as logarithmic value, ln Ω₁ ^∞, and Flory‐Huggins interaction parameters, χ₁₂ ^∞, between the polymer and probes, were estimated. Also, the glass transition temperature,T_g, and the solubility parameter, δ₂, of the graft copolymer, were found to be about 85°C, and between 5.0–6.8 (cal/cm³)^1/2 in the 413–463 temperature range K, respectively, and some extrapolations to room temperature were done and the results were discussed.

Keywords:

• graft copolymer
• poly(ethyl methacrylate)
• thermodynamic properties
• inverse gas chromatography