Coatings Adhesion on Chemically Modified Scots Pine (Pinus sylvestris L.) Woods
Abstract
:1. Introduction
2. Materials and Methods
2.1. Wood Samples
2.2. Coatings
2.3. Test Panel Preparation and Coating Application
2.4. Dry Film Thickness Measurement
2.5. Assessment of Coating Resistance to Detachment in Dry State: Crosscut Test
2.6. Determination of Coating Wear-Resistant Hardness
2.7. Determination of Coating Wet Adhesion Strength: Pull-Off (Tensile) Test
2.8. Statistical Analysis
3. Results and Discussion
3.1. Dry Film Thickness
3.2. Coating Resistance to Detachment in Dry State: Crosscut Adhesion Grading
3.3. Wear-Resistant Hardness of Coatings
3.4. Coating Wet Adhesion (Pull-Off) Strength: Effects of Coating and Wood Modification Types
3.5. Coating Wet Adhesion (Pull-Off) Strength: Fracture Pattern
4. Conclusions
- Coating adhesion on acetylated, DMDHEU- and SorCA-modified P. sylvestris woods exceeded that on unmodified wood, thus making the modified woods suitable substrates for the investigated coatings;
- Contrary to reported instances of adverse effects of thermal modification on coating adhesion, chemical modification is suited to integration with coatings for enhanced wood protection;
- Solvent-based coatings had better adhesion strengths on the acetylated, DMDHEU-modified and unmodified P. sylvestris woods than water-based coatings;
- Coating adhesion on SorCA-modified P. sylvestris wood was mostly better with water-based coatings compared to solvent-based coatings;
- Coatings on acetylated and DMDHEU-modified P. sylvestris woods exhibited wear-resistant hardness that is significantly better than on unmodified wood;
- The wear-resistant hardness of coatings on SorCA-modified wood is comparable to that of unmodified wood;
- Further studies on coating penetration into the modified woods and surface forces would facilitate deeper understanding of the mechanisms of coating adhesion to modified woods. Such deeper understanding could be further explored for a tailored improvement in coating adhesion on modified woods;
- The anti-wetting effect of wood modification combined with the water-repelling properties of coatings as observed in this study offer opportunity for synergistic improvements in wood hydrophobization. Such wood modification–coating synergy could be explored as a more sustainable wood hydrophobization alternative to developing superhydrophobic coatings with potentially harmful substances;
- The long-term behaviour of the coatings on the modified woods still needs to be evaluated through accelerated and outdoor exposure testing. Earlier studies offer hope that the higher dimensional stability of the modified woods leads to better long-term coating performance and fewer maintenance needs.
- Due to limitations concerning the starting material available for this study, the coated wood surfaces included radial and tangential surfaces, randomly distributed. The probable effect of the wood surface type could not be evidently assessed in this study. This can be explored in future studies.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
Appendix A
References
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Coat | Ref. Code | Formulation | Density (g/cm3) * | Dynamic Viscosity (mPa·s) * | Spread Rate (mL/m2) | |
---|---|---|---|---|---|---|
Basis | Binder(s) | |||||
WoodColor m 6.15 W 100 delta glazes 8170 walnut | DL8170 | Water | Pure acrylate | 0.98 | 3596 at 30 rpm SP-3 | 80–150 |
Wood preservative glaze (thin film glaze) KS 7940 ruby grey | H210 | Solvent | Alkyd resin | 0.85 | 77.8 at 60 rpm SP-1 | 80–110 |
Leonardo Hydrolasur (hybrid glaze) KS 7940 ruby grey | H230 | Water | Hybrid: Pure acrylate-alkyd resins | 0.89 | 10.7 at 60 rpm SP-1 | 80–110 |
Hydrostop H2O natural grey KS 7940 ruby grey | H320 | Water-oil complex | Alkyd resin and natural oils | 0.84 | 11.4 at 60 rpm SP-1 | 80–120 |
Lignolan weather protection paint KS 0275 Swedish red | H415 | Water | Pure acrylate | 0.97 | 1556 at 30 rpm SP-3 | 100–150 |
Lignolan Swedish house paint KS 0275 Swedish red | H430 | Water | Alkyd resin | 0.93 | 3408 at 30 rpm SP-3 | 100–150 |
Wood Color m 6.15 W 100 RAL7016 Anthracite Grey | AG7016 | Water | Pure acrylate | 1.06 | 2796 at 30 rpm SP-3 | 80–150 |
Coat | DL8170 | H210 | H230 | H320 | H415 | H430 | AG7016 |
---|---|---|---|---|---|---|---|
Dry-to-touch | 1 h | 6 h | 20 min | 12 h | 1 h | 2 h | 1 h |
Recoatable | 4 h | 24 h | 1 h | Within 8 h * | 4 h | 6 h | 4 h |
Factorial ANOVA | |||||
---|---|---|---|---|---|
Source of Variation | df | Sum of Squares | Mean Squares | F Value | Pr(>F) |
P. sylvestris wood type | 3 | 1044 | 348.0 | 4.107 | 0.0164 * |
Coat | 6 | 5550 | 924.9 | 10.917 | 4.48 × 10−6 *** |
P. sylvestris wood type × Coat | 18 | 1734 | 96.3 | 1.137 | 0.3745 |
Residuals | 26 | 2203 | 84.7 | ||
Tukey Post Hoc Analysis 1 | |||||
Group Comparison | Difference | Lower | Upper | p adj | |
P. sylvestris wood type main effect | |||||
Unmodified-SorCA | 11.79 | 1.89 | 21.70 | 0.015 * | |
Coat main effect | |||||
AG7016-DL8170 | −29.49 | −44.69 | −14.29 | 2.83 × 10−5 *** | |
AG7016-H210 | −23.13 | −37.81 | −8.44 | 5.57 × 10−4 *** | |
H430-H230 | 16.62 | 1.42 | 31.82 | 0.025 * | |
AG7016-H230 | −14.79 | −29.47 | −0.11 | 0.047 * | |
AG7016-H320 | −27.50 | −42.18 | −12.82 | 4.88 × 10−5 *** | |
AG7016-H415 | −23.96 | −38.64 | −9.28 | 3.50 × 10−4 *** | |
AG7016-H430 | −31.41 | −46.61 | −16.22 | 1.03 × 10−5 *** |
Coat | P. sylvestris Wood Type | |||
---|---|---|---|---|
Modified | Unmodified | |||
Acetylated | DMDHEU | SorCA | ||
DL8170 | 0 | 0 | 1 | 0 |
H210 | 0 | 0 | 1 | 0 |
H230 | 0 | 1 | 4 | 0 |
H320 | 0 | 0 | 1 | 0 |
H415 | 2 | 0 | 0 | 0 |
H430 | 1 | 1 | 1 | 1 |
AG7016 | 1 | 0 | 2 | 0 |
Factorial ANOVA | |||||
---|---|---|---|---|---|
Source of Variation | df | Sum of Squares | Mean Squares | F Value | Pr(>F) |
P. sylvestris wood type | 3 | 6.46 | 2.15 | 12.92 | 1.761 × 10−5 *** |
Coat | 6 | 51.86 | 8.64 | 51.86 | 6.989 × 10−14 *** |
P. sylvestris wood type × Coat | 18 | 8.98 | 0.50 | 2.99 | 4.536 × 10−3 ** |
Residuals | 28 | 4.67 | 0.17 | ||
Tukey Post Hoc Analysis 1 | |||||
Group Comparison | Difference | Lower | Upper | p adj | |
P. sylvestris wood type × within-coat interaction effect | |||||
H320 * (SorCA—DMDHEU) | −1.83 | −3.51 | −0.16 | 0.021 * | |
H430 * (Unmodified—Acetylated) | −1.83 | −3.51 | −0.16 | 0.021 * | |
P. sylvestris wood type main effect | |||||
SorCA-Acetylated | −0.81 | −1.23 | −0.39 | 0.000 *** | |
SorCA-DMDHEU | −0.79 | −1.21 | −0.36 | 0.000 *** | |
Unmodified-Acetylated | −0.50 | −0.92 | −0.08 | 0.015 * | |
Unmodified-DMDHEU | −0.48 | −0.90 | −0.05 | 0.022 * |
Factorial ANOVA | |||||
---|---|---|---|---|---|
Source of Variation | df | Sum of Squares | Mean Squares | F Value | Pr(>F) |
P. sylvestris wood type | 3 | 14.74 | 4.91 | 24.80 | 8.77 × 10−7 *** |
Coat | 6 | 22.52 | 3.75 | 18.95 | 4.37 × 10−7 *** |
P. sylvestris wood type × Coat | 16 | 9.71 | 0.61 | 3.07 | 0.01 * |
Residuals | 19 | 3.76 | 0.20 | ||
Tukey Post Hoc Analysis 1 | |||||
Group Comparison | Difference | Lower | Upper | p adj | |
P. sylvestris wood type × within-coat interaction effect | |||||
DL8170 * (Unmodified—Acetylated) | −2.60 | −4.96 | −0.24 | 0.019 * | |
H210 * (SorCA—DMDHEU) | −2.39 | −4.75 | −0.03 | 0.044 * | |
AG7016 * (Unmodified—DMDHEU) | −3.62 | −5.97 | −1.26 | 0.000 *** | |
P. sylvestris wood type main effect | |||||
Unmodified-Acetylated | −1.41 | −1.90 | −0.92 | 0.000 *** | |
Unmodified-DMDHEU | −1.22 | −1.77 | −0.66 | 0.000 *** | |
Unmodified-SorCA | −0.98 | −1.49 | −0.46 | 0.000 *** |
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Alade, A.A.; Hoette, C.; Militz, H. Coatings Adhesion on Chemically Modified Scots Pine (Pinus sylvestris L.) Woods. Forests 2024, 15, 526. https://doi.org/10.3390/f15030526
Alade AA, Hoette C, Militz H. Coatings Adhesion on Chemically Modified Scots Pine (Pinus sylvestris L.) Woods. Forests. 2024; 15(3):526. https://doi.org/10.3390/f15030526
Chicago/Turabian StyleAlade, Adefemi Adebisi, Christoph Hoette, and Holger Militz. 2024. "Coatings Adhesion on Chemically Modified Scots Pine (Pinus sylvestris L.) Woods" Forests 15, no. 3: 526. https://doi.org/10.3390/f15030526
APA StyleAlade, A. A., Hoette, C., & Militz, H. (2024). Coatings Adhesion on Chemically Modified Scots Pine (Pinus sylvestris L.) Woods. Forests, 15(3), 526. https://doi.org/10.3390/f15030526