Abstract
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 and the specific component of surface energy , 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.
Highlights
Larch bark, a by-product of the forestry industry, proanthocyanidins of content as high as10–16% [1,2], Proanthocyanidins, or condensed tannins, are non-toxic, renewable, and biodegradable polyphenolic compounds with good antibacterial and antioxidant properties and strong resistance to UV light [3,4]
Results and Discussion proanthocyanidins are located at 5.8–6.5 ppm and the integrated peak area was recorded as A6,8
Degree of Polymerization of Proanthocyanidins subunit is located at 2.5–3.0 ppm and the integrated peak area was recorded as Ae
Summary
A by-product of the forestry industry, proanthocyanidins of content as high as10–16% [1,2], Proanthocyanidins, or condensed tannins, are non-toxic, renewable, and biodegradable polyphenolic compounds with good antibacterial and antioxidant properties and strong resistance to UV light [3,4]. Polymer composites with specific properties can be formed from proanthocyanidins and higher molecular weight polymers, such as polyvinyl alcohol (PVA) [5,6], polylactic acid [7,8], and soybean protein [9,10]. Wang and Wang [10] added valonea tannin to soybean protein to prepare a tannin/soybean protein composite film that had improved mechanical, antioxidant and UV absorption properties, compared with soybean protein. At higher pH surface acidity and alkalinity affected the interaction of tannin with the composite network, resulting in a decrease in water vapor permeability and oxygen permeability of the film. In another example, Zhai et al [11].
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