The role of nanofillers of various nature in the morphological changes of the polymer binder for plywood production

Abstract

Nanomodification of the adhesive composition is one of the promising methods for improving the quality of wood laminated materials. Morphological changes in nanostructures make it possible to control the functional characteristics of the resulting nanocomposites. The shape and distribution of nanomodifiers of nanocellulose and multi-walled carbon nanotubes of urea-formaldehyde resin used to produce plywood have been studied by atomic force microscopy. The phase composition and crystal structure of biological and carbon nanofillers of the binder are investigated. Data on the qualitative and quantitative composition, structural state of nanocrystalline cellulose and multi-walled carbon nanotubes, as well as cured resin in pure and modified form, were obtained by X-ray diffractometry. The microrelief of the surface of the cured binder in the presence of multi–walled carbon nanotubes is characterized by uniformly distributed nanoclusions of 50 nm – 1 µm; and nanoclusions of 70 nm - 2 µm in the case of resin modification with nanocrystalline cellulose. Unmodified ureaformaldehyde resin is characterized by a low degree of crystallinity: the crystallite size is 10 nm. When modifying the resin with multi–walled carbon nanotubes, the crystal size increases to 18 nm, and when modified with nanocrystalline cellulose - up to 15 nm. The most probable type of lattice of the resin under study is a primitive cubic one with a parameter a = 0.840 nm. An increase in the volume of the unit cell of resin modified with multi-walled carbon nanotubes (a = 0.844 nm) and
nanocrystalline cellulose (a = 0.842 nm) is observed. An increase in the size of the crystalline regions in the resin, as well as an increase in the volume of the resin unit cell as a result of the use of nanomodifiers, can help improve the performance of plywood.