Although lignin blending with thermoplastic polymers has been widely studied, the usefulness of the lignin-polymer composites is limited by the poor compatibility of the two components. In the present study, alkali lignin/PVA composite membranes were prepared by incorporating 10%, 15%, 20% and 25% alkali lignin into the composites. The thermodynamic parameters of the composites were measured using inverse gas chromatography (IGC). Composite membranes with 10%, 15%, 20%, and 25% alkali lignin had solubility parameters of 17.51, 18.70, 16.64 and 16.38 (J/cm 3 ) 0.5 , respectively, indicating that the solubility parameter firstly increased, and then decreased, with increasing proportions of alkali lignin. When the alkali lignin content was 15%, the composites had the largest solubility parameters. The composite membrane with an alkali lignin content of 15% had a tensile strength of 18.86 MPa and a hydrophilic contact angle of 89 • . We have shown that the solubility parameters of blends were related to mechanical and hydrophilic properties of the composites and the relationships have been verified experimentally and theoretically.

The physicochemical properties of alkali lignin are crucial to its potential applications and recyclability, as it is one of the most important natural polymer materials. In this study, the solubility parameter (δ) of alkali lignin was determined using Hansen solubility parameters (HSP) theory and inverse gas chromatography (IGC). The δ of alkali lignin was determined by the IGC technique. Solute retention volumes (Vg 0 ) of 6 solutes were determined using alkali lignin as the stationary phase. From 50 to 110 ºC, the δ of alkali lignin varied from 24.47 to 24.15 MPa 1/2 . Hansen solubility spheres were plotted using the data from the literature for the interactions of alkali lignin with 36 solutes to determine the three dimensional solubility parameter of alkali lignin at 25 to 100 ºC. These determined δ values were consistent with those calculated experimentally via IGC. Acetone was a moderate solvent for the alkali lignin.

Blends of alkali lignin and acrylonitrile–butadiene–styrene (ABS) resin are physically mixed and injected into the injection molding system. Although the components of the blend are bound together by intermolecular forces, noticeable phase separation still occurs. In the present study, inverse gas chromatography technology was used to characterize the Hansen solubility parameters of alkali lignin/ABS blends. The relationship between the Hansen solubility parameters and thermodynamic properties was then determined. Hansen solubility parameters, at room temperature, of alkali lignin/ABS blends containing 0, 10, 20, and 30 wt % alkali lignin were 17.40, 19.20, 18.98, and 17.37 (J/cm 3 ) 0.5 , respectively. Hansen solubility parameters of the blends were shown, both experimentally and theoretically, to be related to their mechanical and thermal properties.

Ｆｏｕｎｄａｔｉｏｎ ｉｔｅｍ： Ｆｕｎｄａｍｅｎｔａｌ Ｒｅｓｅａｒｃｈ Ｆｕｎｄｓ ｆｏｒ ｔｈｅ Ｃｅｎｔｒａｌ Ｕｎｉｖｅｒｓｉｔｉｅｓ (Ｎｏ． ２５７２０１６ＣＢ０１) ．