Surface pre-treatment methods for improving adhesion ability in wood plymer composite for frame and furniture construction applications

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  • PhD, School of Environment, Natural Resources and Geography

Abstract

This study was held to investigate the possibility of improving the WPC adhesion ability by pre-treatment of the material surface. Pre-treatments are used by the polymer industry to oxidize and alter the polymer’s surface to improving the surface energy and adhesion ability, resulting in more effective surface for painting and coating. In some cases,
the pre-treatment methods that the polymer industry uses require expensive and complicated equipment like corona, plasma, and fluorination treatments, and in some cases dangerous chemicals like chromic acid. The adhesion improvement of the WPC is essential for coating, frame construction and furniture manufacture. The lack of effective WPC adhesion limits the
potential usage of the material, to constructions like decking, and the only substantial joining method which are available from today’s manufacturers market, are metallic and plastic fasteners, including nails and screws. Pre-
treatments for improving adhesion could provide the possibility of building structures within a small workshop, increasing the variety of WPC applications. The increase of the WPC usage, could be environmentally beneficial because it
is a part renewable material with the possibility to be part produced from recycled and waste materials. Moreover, it is a weather resistance material with minimum need of preservation.In this study, hydrogen peroxide, hot air gun, flame and halogen heating lamps pre-treatment methods, which could be applied without the usage of sophisticated and expensive equipment, were investigated. In order to evaluate the effectiveness of each
treatment to produce higher adhesion strength a series of experiments were undertaken. Lap joint shear strength of the bonding line was the main test to evaluate the adhesion ability changes of the WPC material. To investigation the reasons that lead to efficient adhesion, surface characterization was also performed. The surface characteristics that were study were Surface roughness, scanning electro n microscopy (SEM), surface energy and FTIR -ATR spectroscopy. The aesthetic aspect of the surface after the pre-treatments was also studied by light microscopy and colour determination. All the treatment methods, except the halogen heating lamp, are able to increase the adhesion strength of the WPC material. All treatments except of the halogen heating lamps, which was reducing the adhesion
strength to values lower than the control samples, were increasing the WPCs adhesion ability to values that causing material failure and not just to bonding line. Surface characterization showed cluster relationships between the adhesion strength and the surface chemistry and morphology but there was not any specific trend that could explain the adhesion behaviour with confidence. However all the treated samples showed some morphologically and chemically modification. The aesthetic investigation of the treated samples showed that there were treatment methods which were causing colour differences which in some cases like flame treatment, were the treatment was more aggressive, the samples appeared to have a more “bunt” appearance. However the bleaching ability of the hydrogen peroxide caused the highest colour difference.

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Original languageEnglish
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Award dateJan 2015