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Roger E. Hernández - One of the best experts on this subject based on the ideXlab platform.

  • Performance of solvent-borne Coating on red oak wood prepared by two alternative surfacing processes
    European Journal of Wood and Wood Products, 2020
    Co-Authors: Bruna Ugulino, Roger E. Hernández
    Abstract:

    The Performance of varnishes applied to wood will depend on the way in which its surfaces have been prepared. Sanding has traditionally been used to prepare surfaces prior to Coating. This process is one of the most expensive operations in woodworking, which produces a high level of wood dust. As a result, other surfacing processes are actually studied as alternatives to sanding for wood finishing. The effects of two alternative processes, oblique cutting and helical planing, on surface properties and Coating Performance of red oak wood were thus studied. Surfaces were prepared using three oblique angles (oblique cutting) and three wavelengths (helical planing) before application of an interior solvent-borne Coating. Surface properties were examined by roughness parameters, scanning electron microscopy micrographs, wetting behavior, and surface energy. Coating Performance was assessed by pull-off tests on aged and un-aged specimens. Oblique and helical planed surfaces at the highest oblique angle and wavelength, respectively, presented micro-torn grain, a certain level of micro-fuzziness, and higher roughness. Oblique-cut surfaces were more wettable than helical-planed surfaces. The wettability of machined surfaces decreased with increasing surface roughness within each process. Despite oblique samples had shown lower values of pull-off strength prior to aging treatment, these surfaces had statistically similar pull-off strength to those of helical-planed specimens after aging. As a result, the latter surfaces had higher loss in adhesion after accelerated aging. Results suggest that the use of oblique angles of 15° and 35° should provide a better Coating Performance in oblique-cut surfaces. On the other hand, no significant differences were detected between wavelengths during helical planing with respect to Coating Performance. Thus, a low (1 mm) or high wavelength (2.1 mm) could be used, depending on whether smoothness or productivity are required, in order to reduce sanding dependence for finishing red oak wood.

  • Analysis of sanding parameters on surface properties and Coating Performance of red oak wood
    Wood Material Science & Engineering, 2016
    Co-Authors: Bruna Ugulino, Roger E. Hernández
    Abstract:

    ABSTRACTSanding is the most common machining process used to prepare wood surfaces prior to Coating. Hence, to improve surface quality and Coating Performance during this process, an optimal set of machining parameters should be established according to wood species and its final use. The effects of grit size and feed speed on surface properties and Coating Performance of red oak wood were studied. Surface quality was assessed by surface roughness, scanning electron micrographs, and wetting analyses. Coating Performance was evaluated using pull-off adhesion tests on coated surfaces before and after an accelerated weathering. The results showed that smoother surfaces are obtained as the grit size number of the abrasive increased. On the other hand, minor differences were observed on cell damages and surface roughness as feed speed changed. Also, there was little difference among treatments concerning wetting behavior and surface energy. Pull-off strength was more affected by changes in grit size than feed ...

  • Assessment of surface properties and solvent-borne Coating Performance of red oak wood produced by peripheral planing
    European Journal of Wood and Wood Products, 2016
    Co-Authors: Bruna Ugulino, Roger E. Hernández
    Abstract:

    Coating Performance on wood could be affected for different aspects including the manner in which the surface is prepared. Peripheral planing is one of the most used machining processes in woodworking. Improving this process would allow to enhance Coating Performance. As a result, the effects of wavelength and rake angle on surface properties and Coating Performance were evaluated in an attempt to improve peripheral planing of red oak wood. Surface quality was assessed through roughness, scanning electron micrographs, and wettability analyses. The Performance of a solvent-borne Coating was measured by adhesion strength before and after accelerated aging. Surface roughness and energy components increased as rake angle increased. As wavelength increased, cell damage and surface roughness increased. Surfaces prepared with a rake angle of 25° had more cell-wall fibrillation, which was assumed to be responsible for increased surface energy and improved Coating adhesion after weathering. Samples machined with this rake angle combined with a short wavelength resulted in the lowest loss of adhesion after aging and presented an acceptable level of surface roughness.

Bruna Ugulino - One of the best experts on this subject based on the ideXlab platform.

  • Performance of solvent-borne Coating on red oak wood prepared by two alternative surfacing processes
    European Journal of Wood and Wood Products, 2020
    Co-Authors: Bruna Ugulino, Roger E. Hernández
    Abstract:

    The Performance of varnishes applied to wood will depend on the way in which its surfaces have been prepared. Sanding has traditionally been used to prepare surfaces prior to Coating. This process is one of the most expensive operations in woodworking, which produces a high level of wood dust. As a result, other surfacing processes are actually studied as alternatives to sanding for wood finishing. The effects of two alternative processes, oblique cutting and helical planing, on surface properties and Coating Performance of red oak wood were thus studied. Surfaces were prepared using three oblique angles (oblique cutting) and three wavelengths (helical planing) before application of an interior solvent-borne Coating. Surface properties were examined by roughness parameters, scanning electron microscopy micrographs, wetting behavior, and surface energy. Coating Performance was assessed by pull-off tests on aged and un-aged specimens. Oblique and helical planed surfaces at the highest oblique angle and wavelength, respectively, presented micro-torn grain, a certain level of micro-fuzziness, and higher roughness. Oblique-cut surfaces were more wettable than helical-planed surfaces. The wettability of machined surfaces decreased with increasing surface roughness within each process. Despite oblique samples had shown lower values of pull-off strength prior to aging treatment, these surfaces had statistically similar pull-off strength to those of helical-planed specimens after aging. As a result, the latter surfaces had higher loss in adhesion after accelerated aging. Results suggest that the use of oblique angles of 15° and 35° should provide a better Coating Performance in oblique-cut surfaces. On the other hand, no significant differences were detected between wavelengths during helical planing with respect to Coating Performance. Thus, a low (1 mm) or high wavelength (2.1 mm) could be used, depending on whether smoothness or productivity are required, in order to reduce sanding dependence for finishing red oak wood.

  • Analysis of sanding parameters on surface properties and Coating Performance of red oak wood
    Wood Material Science & Engineering, 2016
    Co-Authors: Bruna Ugulino, Roger E. Hernández
    Abstract:

    ABSTRACTSanding is the most common machining process used to prepare wood surfaces prior to Coating. Hence, to improve surface quality and Coating Performance during this process, an optimal set of machining parameters should be established according to wood species and its final use. The effects of grit size and feed speed on surface properties and Coating Performance of red oak wood were studied. Surface quality was assessed by surface roughness, scanning electron micrographs, and wetting analyses. Coating Performance was evaluated using pull-off adhesion tests on coated surfaces before and after an accelerated weathering. The results showed that smoother surfaces are obtained as the grit size number of the abrasive increased. On the other hand, minor differences were observed on cell damages and surface roughness as feed speed changed. Also, there was little difference among treatments concerning wetting behavior and surface energy. Pull-off strength was more affected by changes in grit size than feed ...

  • Assessment of surface properties and solvent-borne Coating Performance of red oak wood produced by peripheral planing
    European Journal of Wood and Wood Products, 2016
    Co-Authors: Bruna Ugulino, Roger E. Hernández
    Abstract:

    Coating Performance on wood could be affected for different aspects including the manner in which the surface is prepared. Peripheral planing is one of the most used machining processes in woodworking. Improving this process would allow to enhance Coating Performance. As a result, the effects of wavelength and rake angle on surface properties and Coating Performance were evaluated in an attempt to improve peripheral planing of red oak wood. Surface quality was assessed through roughness, scanning electron micrographs, and wettability analyses. The Performance of a solvent-borne Coating was measured by adhesion strength before and after accelerated aging. Surface roughness and energy components increased as rake angle increased. As wavelength increased, cell damage and surface roughness increased. Surfaces prepared with a rake angle of 25° had more cell-wall fibrillation, which was assumed to be responsible for increased surface energy and improved Coating adhesion after weathering. Samples machined with this rake angle combined with a short wavelength resulted in the lowest loss of adhesion after aging and presented an acceptable level of surface roughness.

Carsten Mai - One of the best experts on this subject based on the ideXlab platform.

  • Coating Performance on glutaraldehyde-modified wood
    Journal of Forestry Research, 2018
    Co-Authors: Zefang Xiao, Carsten Mai, Holger Militz, Haiou Chen, Yanjun Xie
    Abstract:

    Scots pine (Pinus sylvestris L.) panels were modified with glutaraldehyde (GA) to various weight percent gains and subsequently coated with several commercial Coatings. The drying rate and adhesion of the Coatings on the modified wood were measured; the coated/modified woods were exposed outdoors to analyze how the wood modifications influence the Coating deterioration. The results showed that GA modification caused an increase in the drying rate of the waterborne Coatings, but had no influence on drying of tested solvent-borne Coatings. GA-modification did not change the dry adhesion but reduced the wood strength in a pull-off test. Wet adhesion of waterborne Coatings was improved, while that of the solvent-borne Coatings tended to be somewhat reduced. During 22 months of outdoor weathering, the coated/modified samples exhibited lower moisture content than the coated/unmodified samples, but GA modification didn’t contribute a substantially synergistic effect with surface Coatings on resistance to weathering.

  • Coating Performance of finishes on wood modified with an n methylol compound
    Progress in Organic Coatings, 2006
    Co-Authors: Yanjun Xie, Andreas Krause, Holger Militz, Carsten Mai
    Abstract:

    This study describes the effects of wood modification with modified 1,3-dimethylol-4,5-dihydroxyethyleneurea (mDMDHEU) on the Coating Performance of solvent- and water-borne finishes. Although the basic colour of wood was slightly changed due to the modification, modified and unmodified samples did not display any colour differences after Coating with translucent stains. Blocking of coated wooden substrates (degree of adhesiveness) was dependant on the type of finish system and, in a few cases, on the wood substrate. For all wood substrates, both treated and untreated, solvent-borne alkyd finish penetrated into the surface layers of the wood cells, while water-borne acrylic finishes spread only on the wood surfaces. The solvent-borne alkyd finish dried much more slowly on wood substrates than did the water-borne acrylics. Modification with mDMDHEU did not affect the drying rates of the finishes tested. The wet adhesion depended on the finish systems tested and on the pre-treatment of the wooden substrate. With regard to the pre-treatment, wet adhesion of one water-borne and the solvent-borne finish systems was significantly enhanced through precedent modification with mDMDHEU. The other two water-borne finish systems showed a higher degree of wet adhesion. This study demonstrates that modification of the wood substrate with mDMDHEU is compatible with both water-borne and solvent-borne finish systems and improves their wet adhesion on the wood surface.

Yanjun Xie - One of the best experts on this subject based on the ideXlab platform.

  • Coating Performance on glutaraldehyde-modified wood
    Journal of Forestry Research, 2018
    Co-Authors: Zefang Xiao, Carsten Mai, Holger Militz, Haiou Chen, Yanjun Xie
    Abstract:

    Scots pine (Pinus sylvestris L.) panels were modified with glutaraldehyde (GA) to various weight percent gains and subsequently coated with several commercial Coatings. The drying rate and adhesion of the Coatings on the modified wood were measured; the coated/modified woods were exposed outdoors to analyze how the wood modifications influence the Coating deterioration. The results showed that GA modification caused an increase in the drying rate of the waterborne Coatings, but had no influence on drying of tested solvent-borne Coatings. GA-modification did not change the dry adhesion but reduced the wood strength in a pull-off test. Wet adhesion of waterborne Coatings was improved, while that of the solvent-borne Coatings tended to be somewhat reduced. During 22 months of outdoor weathering, the coated/modified samples exhibited lower moisture content than the coated/unmodified samples, but GA modification didn’t contribute a substantially synergistic effect with surface Coatings on resistance to weathering.

  • Coating Performance of finishes on wood modified with an n methylol compound
    Progress in Organic Coatings, 2006
    Co-Authors: Yanjun Xie, Andreas Krause, Holger Militz, Carsten Mai
    Abstract:

    This study describes the effects of wood modification with modified 1,3-dimethylol-4,5-dihydroxyethyleneurea (mDMDHEU) on the Coating Performance of solvent- and water-borne finishes. Although the basic colour of wood was slightly changed due to the modification, modified and unmodified samples did not display any colour differences after Coating with translucent stains. Blocking of coated wooden substrates (degree of adhesiveness) was dependant on the type of finish system and, in a few cases, on the wood substrate. For all wood substrates, both treated and untreated, solvent-borne alkyd finish penetrated into the surface layers of the wood cells, while water-borne acrylic finishes spread only on the wood surfaces. The solvent-borne alkyd finish dried much more slowly on wood substrates than did the water-borne acrylics. Modification with mDMDHEU did not affect the drying rates of the finishes tested. The wet adhesion depended on the finish systems tested and on the pre-treatment of the wooden substrate. With regard to the pre-treatment, wet adhesion of one water-borne and the solvent-borne finish systems was significantly enhanced through precedent modification with mDMDHEU. The other two water-borne finish systems showed a higher degree of wet adhesion. This study demonstrates that modification of the wood substrate with mDMDHEU is compatible with both water-borne and solvent-borne finish systems and improves their wet adhesion on the wood surface.

J.h.w. De Wit - One of the best experts on this subject based on the ideXlab platform.

  • Dielectric properties reflecting Coating Performance
    Materials Science Forum, 1998
    Co-Authors: E.p.m. Van Westing, D.h. Van Der Weijde, S. Bonincontro, M.p.w. Vreijling, G.m. Ferrari, J.h.w. De Wit
    Abstract:

    The use of Electrochemical Impedance Spectroscopy (EIS) in Coatings research is widespread. The information obtained by this technique is often limited, which is the result of too high expectations and inadequate analysis and interpretation. Analysis of the dielectric properties of organic Coatings using a Constant Phase Element (CPE) in the equivalent circuit reveals detailed information on Coating properties as curing stage, water uptake and electrolyte sensitivity, swelling and onset of delamination, but also on the weathering of the Coating. The determination of weathering using EIS is developed further and a quantitative parameter the Weathering Index W is introduced. Examples of results on Coatings exposed to several types of accelerated weathering are given.

  • The determination of Coating Performance using electrochemical impedance spectroscopy
    Electrochimica Acta, 1994
    Co-Authors: E.p.m. Van Westing, G.m. Ferrari, J.h.w. De Wit
    Abstract:

    Epoxy model Coatings were investigated while immersed in a 3% NaCl solution using Electrochemical Impedance Spectroscopy (EIS) during the first stage of the exposure where water uptake is the main process and during long term exposure where the corrosion starts. The analysis of the impedance measurements showed the necessity of the use of the Constant Phase Element (cpe) in the equivalent circuit of the impedance. A short review of literature on cpe-interpretations is given. From literature it is derived that deviation from ideal dielectrical properties, that is represented by a cpe, originates from interaction (shielding) of polarizable groups. The results of impedance measurements on the water uptake of the Coatings, show that the entering water not only affects the dielectrical properties but also yields swelling of the Coating polymer. The water uptake and the swelling of the Coating polymer were analyzed and quantified from the results of the impedance measurements using a novel method. Impedance measurements during the long term immersion of the Coating show that the start of the corrosion process under high impedant barrier type Coatings can be detected by changes of the dielectrical properties of the Coating, resulting in changes of the parameters of the cpe. The difference in results interpreting the impedance measurements using a capacitor of a cpe in the equivalent circuit is also discussed.

  • The determination of Coating Performance with impedance measurements-I. Coating polymer properties
    Corrosion Science, 1993
    Co-Authors: E.p.m. Van Westing, G.m. Ferrari, J.h.w. De Wit
    Abstract:

    Abstract Modern Coatings with new binders and pigmentation require new methods to optimize the formulation with respect to the protection of the metal substrate against corrosion. The methods normally used for accelerated weathering do not give information about the mechanism of failure of the Coatings. Mechanistic information is necessary for a fast and more specific development of new Coatings for various applications. Electrochemical impedance spectroscopy (EIS) can provide information. This article is part one in a series. The Coating polymer properties and Coatings Performance are discussed. Moreover the experimental results are validated with respect to experimental errors. Models from the literature have also been included in the discussion. For the study of the curing mechanism and mechanical properties of the epoxy Coatings the constant phase element (CPE) was found to be a valuable component in the equivalent circuit used for EIS. The values of the CPE parameters Y 11 and n are related to properties of the network of the Coating polymer.