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Moubarik A.,Sylvadour | Charrier B.,Sylvadour | Allal A.,University of Pau and Pays de lAdour | Charrier F.,Sylvadour | Pizzia A.,University of Lorraine
European Journal of Wood and Wood Products | Year: 2010

The development and optimization of a new, environment-friendly adhesive made from abundant and renewable cornstarch and tannin is described in this study. At present, the production of wood composites mainly relies on petrochemical- and formaldehyde-based adhesives such as phenol-formaldehyde (PF) resins and urea-formaldehyde (UF) resins. Formaldehyde-free cornstarch plus tannin adhesives were evaluated for mechanical and physical properties (shear strength, rheological characterisation and thermogravimetric analysis). First, optimized conditions for the preparation of cornstarch- sodium hydroxide wood adhesives were determined. The parameters studied were the following: total solids content of the adhesives, sodium hydroxide concentration and sodium hydroxide/cornstarch volume ratio. The highest shear strength results appeared to be 0.5 sodium hydroxide/ cornstarch volume ratio when using concentrations of cornstarch (65% p/v H2O) and sodium hydroxide (33% p/v H2O). The optimum cure temperature was 170 °C and the cure time 4 min. The addition of two types of tannin-based adhesives, Mimosa and Quebracho, with hexamethylenetetramine (hexamine) hardener to the cornstarch-sodium hy- droxide formulation improved the shear strength and decreased the viscosity of adhesives.

Moubarik A.,Sylvadour | Allal A.,University of Pau and Pays de lAdour | Pizzi A.,University of Lorraine | Charrier F.,Sylvadour | Charrier B.,Sylvadour
European Journal of Wood and Wood Products | Year: 2010

This study investigated the physical properties (rheological and thermogravimetric analysis) of cornstarch-tannin adhesives and the mechanical properties (dry tensile strength and 3-point bending strength) of plywood made using cornstarch-tannin adhesives. This adhesive was evaluated for its utility in interior plywood manufacture. The optimum cure temperature and cure time of cornstarch-tannin adhesives were 170°C and 4 min, respectively. Plywood bonded with formaldehyde-free cornstarch-tannin adhesive exhibited excellent mechanical properties comparable to commercially available phenol-formaldehyde plywood adhesives. It was found that cornstarch-tannin panels which do not contain formaldehyde and with an emission equal to that of heated but unbound wood can be obtained by the use of hexamethylenetetramine (hexamine) as hardener. The work has indicated that an environmentally friendly wood adhesive can be prepared from a natural renewable resource (cornstarch and wattle tannin) for bonding interior-type plywood. © 2009 Springer-Verlag Zusammenfassung.

Ben Mbarek T.,H+ Technology | Robert L.,Toulouse 1 University Capitole | Hugot F.,University of Limoges | Orteu J.J.,Toulouse 1 University Capitole | And 3 more authors.
EPJ Web of Conferences | Year: 2010

In this study, the mechanical properties and microstructure of HDPE/wood fibre composites are investigated. The four-point bending and tensile behaviour of Wood Plastic Composite (WPC) with or without additive are studied by using full-field strain measurements by 3-D Digital Image Correlation (3-D DIC). A non-linear behaviour is shown. The modulus of elasticity (MOE) is calculated as the tangent at zero strain of a Maxwell-Bingham model fitted onto experimental data. Four-point bending tests are analyzed thanks to the spatial standard deviation of the longitudinal strain field to determine the degree of heterogeneity. Cyclic tensile tests have been performed in order to analyze the damage of the material. Moreover, Scanning Electron Microscope (SEM) is used to characterize the morphology of the wood fibre/HDPE matrix interface for specimens with maleic anhydride modified polyethylene additive (MAPE). © 2010 Owned by the authors, published by EDP Sciences.

Mbarek T.B.,Ecole de Technologie Superieure of Montreal | Robert L.,CNRS Clement Ader Institute | Sammouda H.,University of Sousse | Charrier B.,Sylvadour | And 2 more authors.
Journal of Reinforced Plastics and Composites | Year: 2013

The wood plastic composites studied in this work are composed of high-density polyethylene matrix and Pinus pinaster wood fibers. Despite some interesting intrinsic properties, this wood plastic composite has limited mechanical properties because of the incompatibility between the polar hydrophilic fibers and the non-polar hydrophobic matrix. In this study, the effects of maleic anhydride-modified polyethylene additive, of carbon chains grafted by acetylation and of wood fiber contents on the tensile mechanical properties of the wood plastic composite were studied. Tensile tests were carried out using digital image correlation as an intrusiveness and robust method for strain measurements. Results showed first that the addition of wood fibers made the wood plastic composite stiffer but less flexible. Acetylation improved the interfacial adhesion properties: the Young modulus was increased and a lower strain at failure was reported. The coupling agent also increased the compatibility but mainly in the case where there was no grafted chain. With regard to the carbon chains, the number of grafts improved the elastic properties while their length did not appear to have any influence. Finally, a scanning electron microscope was used to characterize the post-mortem morphology of the fracture surfaces, the results of which supported the observations obtained from the tensile mechanical properties. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Moubarik A.,Sylvadour | Moubarik A.,University of Lorraine | Moubarik A.,University of Pau and Pays de lAdour | Allal A.,University of Pau and Pays de lAdour | And 3 more authors.
Maderas: Ciencia y Tecnologia | Year: 2010

In this presented work, we describe the development and characterization of a new, environmentally friendly adhesive derived from cornstarch and tannins. The production of wood composites mainly relies on the petrochemical-based and formaldehyde-based adhesives such as urea formaldehyde (UF), phenol formaldehyde (PF) and melamine urea formaldehyde (MUF), which can generate under certain conditions, problems for health and environment. The aim of our work is to replace totally these synthetic resins. In order to evaluate the quality of cornstarch-tannin adhesives, particleboards were produced and physical and mechanical properties were investigated. These physical properties included rheological, thermogravimetric analysis and solid phase 13C NMR analysis of resins. Internal bond, surface soundness, modules of rupture and modulus of elasticity mechanical properties of particleboards bonded with cornstarch-tannin adhesives were also determined. Particleboards bonded with formaldehyde-free cornstarch-tannin adhesive showed comparable mechanical properties to the panels made with the commercial UF resins and satisfied the exigencies of panels for interior fittings used in dry medium (P2) according to European norms EN 312 (2004). Beyond 4 hours, rheological characterization show excellent structural stability of cornstarch-tannin adhesive.

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