Investigation of the Interaction of Water–Glycerin Mixture and Sawdust of Larch Larix sibirica Ledeb (Pinaceae)

Objective: The interaction of the eutectic plasticizer—aqua complex “glycerin–water” with sawdust of larch wood of two fractional compositions was studied: a fine fraction (wood flour) and a coarse fraction (sawdust) with a particle size of 1−3 mm. Methods: The methods of optical microscopy were used to study the surface properties of samples, to measure the dynamic viscosity of spent solutions on a Brookfield viscometer; to measure the VGS retention index, a modified Jaime water retention technique was used. The obtained data are compared with the results of previous studies, in which it was shown that arabinogalactan (AG) performs the functions of a eutectic plasticizer in the structure of larch wood and is in the form of an aqua complex «AG–water». Results and Discussion: It was found that the amount of the attached aqua-complex—“glycerin−water” to the samples of larch sawdust corresponds to the amount of AG previously extracted from sawdust. The process of replacing the aqua-complex “AG−water” with the aqua-complex “glycerin–water” is analyzed on the diagram of relaxation states “two polymers–solvent.” The experimental results are interpreted on the basis of previously obtained data on the effect of water and glycerin on the relaxation state of polymer components of wood. Conclusions: The fundamental difference between the two eutectic plasticizers is demonstrated: if, when drying larch wood, the destruction of the aqua-complex “AG−water” leads to the transfer of polymer components of wood from a highly elastic to a glassy state, then when using the aqua-complex “glycerin−water” (VGS), water is removed during drying, and the remaining glycerin ensures the preservation of polymer components of wood in a highly elastic state. The possible technological aspects of the revealed patterns are considered.