Cellulose Nano Crystals (CNC) as Additive for a Bio-Based Waterborne Acrylic Wood Coating: Decay, Artificial Weathering, Physical and Chemical Tests

Abstract

Wood coatings prolong the service life of wood-based products, but they are usually of synthetic origin. The aim of the present article is to reduce the fossil-based compounds in a commercial waterborne acrylic coating by CNC addition and to test its performance. The coatings were applied on European beech and Norway spruce wood in order to test durability against Gloeophyllum trabeum (brown wood rot) and Trametes versicolor (white wood rot). Artificial weathering and blue stain, contact angle, physical tests (adhesion, impact and scratch test), chemical (FTIR) and morpho-anatomical analysis (SEM) were carried out. CNC addition increased viscosity, limiting the spreading of the coating into wood pores as visible after SEM observation, which reduced coating adhesion on the substrate. CNC improved fungal resistance as seen by a reduced mass loss and FTIR spectroscopy thanks to crosslinks formation, which reduced water sorption as well. Color change was not significant, and, on the other hand, glossiness was reduced but resulted as more homogeneous than control. CNC addition gave good results also in blue stain protection. CNC improved scratch resistance, but no visible change to impact was registered. CNC has promising results in coatings depending on wood and fungal species and presence of further commercial additives (biocides).

Lignin Nanoparticles with Entrapped Thymus spp. Essential Oils for the Control of Wood-Rot Fungi

“…In a recent work, the authors studied in vitro the antifungal effects of pure thyme EOs against brown-rot (Gloeophyllum trabeum and Poria monticola) as well as white-rot fungi (T. versicolor and Pleurotus ostreatus) and proved their efficiency as biocides against wood-rot fungi [22]. Other alternatives for greener wood protection approaches are the substitution of fossil-based components in commonly used wood protection formulations with bio-based additives or, e.g., the utilization of lignin nanoparticles (LNPs) as coatings or as carriers of bioactives [4,25,[58][59][60][61][62][63][64][65][66][67][68][69].…”

Nanocellulose, a Renewable Biobased Functional/Reinforcement Additive for Composite Coating Materials: A Review

“…When the water dries, the CNC forms aggregates within the gaps between the latex particles but the film coalescence is not affected; 15 wt % CNC showed a nearly 230% increase in Koenig hardness and a 10-fold increase in nanoindentation hardness compared to pure films. Tamantini et al 82 In some other studies, NC is mixed with other substances or modified NC is used as an enhancer. Hochmanśka-Kaniewska al.…”

“…When the water dries, the CNC forms aggregates within the gaps between the latex particles but the film coalescence is not affected; 15 wt % CNC showed a nearly 230% increase in Koenig hardness and a 10-fold increase in nanoindentation hardness compared to pure films. Tamantini et al added natural CNC to prepare more eco-friendly commercial water-based acrylic coatings and utilized them in European beech and Norwegian spruce wood. The addition of CNC creates a cross-link in the coating material, improving the durability of the coating against a brown rot fungus (Gloeophyllum trabeum (Pers.)…”

Spray Coating of Wood with Nanoparticles from Lignin and Polylactic Glycolic Acid Loaded with Thyme Essential Oils

“…Other options to make wood protection more environmentally friendly is to replace fossil-based ingredients in traditional wood protection formulations with bio-based additives like lignin or to use lignin nanoparticles (LNPs) as coatings or as carriers of bioactives [37,[43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60]. Lignin coatings were investigated in a wide range of applications [61][62][63], including as water vapor and oxygen barriers in fiber-based packaging solutions [64], as protective coatings for natural fibers for textile production [65], or for the surface modification of paper products [66,67].…”