Is Inverse Gas Chromatography (IGC) a Convenient Method to Determine Compatibility of Rubber Materials?

New Advances on the Dispersive and Polar Surface Properties of Poly(styrene-co-butadiene) Using Inverse Gas Chromatography

The dispersive and polar properties of materials, and especially of polymers and copolymers, play an important role in several engineering applications implying their surfaces and interfaces. The surface energetic properties of poly(styrene-co-butadiene) have never been studied. We proposed in this study an accurate determination of such properties by using inverse gas chromatography (IGC) at infinite dilution.

BACKGROUND

The IGC surface technique led to the dispersive and polar properties of poly(styrene-co-butadiene) rubber (SBR) by adsorption of organic solvents at various temperatures.

METHODS

Our new methodology, based on the thermal Hamieh model and the London dispersion interaction energy, was used to determine the London dispersion surface energy, the polar acid-base surface energy, and the Lewis acid-base properties of the copolymer.

RESULTS

The different surface energy parameters of the SBR were obtained as a function of temperature from the chromatographic measurements.

CONCLUSIONS

The dispersive and polar free energies of adsorption of the various n-alkanes and polar molecules on poly(styrene-co-butadiene) were determined at different temperatures. A decrease in the London dispersive surface energy and the polar Lewis acid-base surface energies of SBR was highlighted when the temperature increased. It showed a Lewis amphoteric character of poly(styrene-co-butadiene) with a highest basic constant 10 times larger than its acidic constant. This new and original method can better characterize the surface thermodynamic properties of poly(styrene-co-butadiene).

Quantitative Analysis of Solubility Parameters and Surface Properties of Larch Bark Proanthocyanidins

Quantitative characterization of the solubility parameters and surface properties of larch bark proanthocyanidins will lay the foundation for quantitative studies of the interfacial interactions of proanthocyanidin/polymer composites and will improve the compatibility of components, with important practical and scientific significance. Here, the solubility parameters of highly polymerized larch polymeric proanthocyanidins (LPPCs) and less highly polymerized larch oligomeric proanthocyanidins (LOPCs) were determined experimentally by inverse gas chromatography (IGC). These values were then compared with the solubility parameters obtained using molecular dynamics simulations. The experimentally measured solubility parameters of LPPCs and LOPCs (20.5 and 22.09 (J/m⁻³)^0.5, respectively) were in good agreement with the solubility parameters determined by molecular dynamics simulations (20.57 and 22.35 (J/m⁻³)^0.5, respectively. IGC was also used to experimentally determine the total surface energy, which includes the dispersive component of surface energy γsd  and the specific component of surface energy γssp, together with the surface acidity and basicity parameters of LPPCs and LOPCs at different temperatures. The surface properties of proanthocyanidins can be quickly and accurately evaluated by IGC, and both LPPCs and LOPCs were shown to be amphoteric materials. This study provides theoretical and technical support for the use of larch bark proanthocyanidins, which are non-toxic, renewable, and have good ultraviolet resistance, in the field of blending composites. The study also provides a reference for other studies on the interfacial interactions of wood fiber polymer composites.