Abstract
Pendulum hardness, which is widely used in the characterization of organic coatings, depends greatly on the thickness of the coating. However, it is still unclear whether a qualitative or quantitative relationship exists between pendulum hardness and coating thickness. In the present article, the pendulum hardness values of acrylic coatings with different thicknesses are measured using a König pendulum hardness tester to clarify the dependence of pendulum hardness on thickness of coating. The results show that the pendulum hardness of acrylic coatings decreases gradually with the increasing thickness of coating within a thickness range, and the sensitivity of pendulum hardness to thickness of coating depends greatly on the glass transition temperature of the coatings. An equation suitable for describing the relationship between logarithmic decrement of the amplitude of pendulum's oscillation and thickness of coating is presented, which can separate the contributions of substrate and coating on the logarithmic decrement. This study demonstrates that the measured value of pendulum hardness is not the bulk hardness value for the coating but the representative value of the system consisting of substrate and coating. An excellent correlation between pendulum hardness and thickness of acrylic coatings is obtained, which is fairly supported by the experimental data.
References
Choi, JH, Kim, HJ, “Three Hardness Test Methods and Their Relationship on UV-Curable Epoxy Acrylate Coatings for Wooden Flooring Systems.” J. Ind. Eng. Chem., 12 (3) 412–417 (2006)
Wei, PJ, Lin, JF, “A New Method Developed to Evaluate both the Hardness and Elastic Modulus of a Coating-Substrate System.” Surf. Coat. Technol., 200 (7) 2489–2496 (2005)
Iost, A, Najjar, D, Hellouin, R, “Modelling of the Vickers Hardness of Paint Coatings Deposited on Metallic Substrates.” Surf. Coat. Technol., 165 (2) 126–132 (2003)
Fernandes, JV, Menezes, LF, Trindade, AC, “The Coated Surface Hardness: A Kinematic Model.” Thin Solid Films, 335 (1–2) 153–159 (1998)
Fernandes, JV, Trindade, AC, Menezes, LF, Cavaleiro, A, “A Model for Coated Surface Hardness.” Surf. Coat. Technol., 131 (1–3) 457–461 (2000)
Iost, A, Bigot, R, “Hardness of Coatings.” Surf. Coat. Technol., 80 (1–2) 117–120 (1996)
Chen, J, Bull, SJ, “On the Factors Affecting the Critical Indenter Penetration for Measurement of Coating Hardness.” Vacuum, 83 (6) 911–920 (2009)
Dashtizadeh, A, Abdouss, M, Mahdavi, H, Khorassani, M, “Acrylic Coatings Exhibiting Improved Hardness, Solvent Resistance and Glossiness by Using Silica Nano-Composites.” Appl. Surf. Sci., 257 (6) 2118–2125 (2011)
Moon, JI, Lee, YH, Kim, HJ, “Synthesis and Characterization of Elastomeric Polyester Coatings for Automotive Pre-coated Metal.” Prog. Org. Coat., 74 (1) 125–133 (2012)
Moon, JI, Lee, YH, Kim, HJ, Schwartz, S, Rafailovich, M, Sokolov, J, “Investigation of the Peel Test for Measuring Self-Cleanable Characteristic of Fluorine-Modified Coatings.” Polym. Test., 31 (3) 433–438 (2012)
Salleh, NGN, Yhaya, MF, Hassan, A, Bakar, AA, Mokhtar, M, “Effect of UV/EB Radiation Dosages on the Properties of Nanocomposite Coatings.” Radiat. Phys. Chem., 80 (2) 136–141 (2011)
Jian, Z, Yong, H, Ming, X, Jun, N, “Preparation and Properties of Dual-Cure Polyurethane Acrylate.” Prog. Org. Coat., 66 (1) 35–39 (2009)
Kivit, PJJ, Aramendia, E, Cabrera, AA, Rios, LM, “Water-Based Coatings Based on Mixtures of Acrylic Dispersions and Alkyd Emulsions.” Macromol. Symp., 283–284 (1) 290–299 (2009)
Cho, JD, Hong, JW, “UV-Initiated Free Radical and Cationic Photopolymerizations of Acrylate/Epoxide and Acrylate/Vinyl Ether Hybrid Systems With and Without Photosensitizer.” J. Appl. Polym. Sci., 93 (3) 1473–1483 (2004)
Fink-Jensen, P, Hardness Testing of Organic Coatings Pure and Applied Chemistry, 1st ed. Butterworths, London (1965)
Hwang, HD, Lee, BH, Choi, JH, Kim, HJ, Chung, WY, “Acoustic Property and Hardness of Coatings for Musical Instruments with Various Coating Thicknesses.” Mokchae Konghak, 34 (2) 58–67 (2006)
Sato, K, “Physical Significance of the Pendulum Hardness of Coatings Films.” J. Coat. Technol., 56 (708) 47–57 (1984)
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Ma, X., Qiao, Z., Huang, Z. et al. The dependence of pendulum hardness on the thickness of acrylic coating. J Coat Technol Res 10, 433–439 (2013). https://doi.org/10.1007/s11998-013-9477-3
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DOI: https://doi.org/10.1007/s11998-013-9477-3