aThünen Institute of Wood Research, Leuschnerstraße 91c, 21031 Hamburg, Germany
bInstitute of Mechanical Wood Technology, Department of Wood Sciences, University of Hamburg, Leuschnerstraße 91c, 21031 Hamburg, Germany
Received 20 October 2015. Revised 19 January 2016. Accepted 6 February 2016. Available online 13 February 2016.
Highlights
Recycled WEEE-plastics and particleboard were investigated for potential use in WPC.
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Increasing wood content resulted in increased stiffness and strength of WPC.
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The coupling agent SMA affected strength properties but not the stiffness of WPC.
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Elementary analysis obtained content of Cd, Cr, Cu, As and Pb in recycled resources.
Abstract
Wood–plastic composites were injection-molded from recycled acrylonitrile–butadiene–styrene and polystyrene from post-consumer electronics in the interest of resource efficiency and ecological product design. The wood content was raised in two steps from 0% to 30% and 60%. Reinforcement performance of recycled particleboard was compared to virgin Norway spruce. Styrene maleic anhydride copolymer was used as the coupling agent in the composites with a 60% wood proportion to investigate the influence on interfacial adhesion. The composites were characterized by using physical and mechanical standard testing methods. Results showed increased stiffness (flexural and tensile modulus of elasticity), water uptake and density with the incorporation of wood particles to the plastic matrices. Interestingly, strength (flexural and tensile) increased as well. Wood particles from Norway spruce exhibited reinforcement in terms of strength and stiffness. The same results were achieved with particleboard particles in terms of stiffness, but the strength of the composites was negatively affected. The coupling agent affected the strength properties beneficially, which was not observed for the stiffness of the composites. The presence of cadmium, chromium, copper, arsenic and lead in the recycled resources was found by an elementary analysis. This can be linked to color pigments in recycled plastics and insufficient separation processes of recycled wood particles for particleboard production.
Fraunhofer Institute for Wood Research (Wilhelm-Klauditz-Institute WKI), Bienroder Weg 54E, 38108 Braunschweig, Germany
Received 21 July 2015. Revised 3 January 2016. Accepted 25 January 2016. Available online 28 January 2016.
Abstract
Flame retardancy of wood-plastic composites (WPC) needs to be improved to widen the applications for these composites. This may be accomplished by protecting both polymer matrix and wood filler with a fire-retardant (FR). In this study, hardly inflammable particleboard converted into wood flour (B1-particleboard flour) was used in combination with several halogen-free FRs. The fire performance and thermal properties of the WPC (matrix: recycled polypropylene) were investigated using limiting oxygen index analysis (LOI), a modified single-flame source test, fire shaft test and thermogravimetric analysis (TGA). The combination of B1-particleboard flour, expandable graphite and red phosphorous led to the highest LOI (38.3). However, at the same time, relatively high water absorption of this formulation was observed which was attributed to the reaction of ammonium polyphosphate in the B1-particleboard flour and red phosphorous which was added during the compounding step, leading to increased hydrophilicity of the composite. The combination of B1-particleboard flour and ammonium polyphosphate (APP) or phosphorized expandable graphite to protect the polymer matrix offered the best overall performance when taking into account LOI (here: 34–35), tensile strength, modulus of elasticity and water absorption values. The WPC-formulation including B1-particleboard flour and APP did not pass the requirements of the German fire shaft test according to DIN 4102-1, however, the duration until smoke gas temperature exceeded 200 °C was more than doubled compared to a commercial WPC-profile based on PP without fire-retardants. The modified single-flame source test showed that all WPC formulations were self-extinguishing.
Published Date 10 September 2012, Vol.543:165–171,doi:10.1016/j.tca.2012.05.016 Author
Helene Jeske
Arne Schirp
Frauke Cornelius
Abstract
A special thermogravimetric analysis (TGA) method was developed to quantify the mass percentage of wood flour and polypropylene copolymer in wood plastic composites (WPC). Step separation of TGA curves was used for quantitative analysis. Four thermal degradation steps were identified and allocated to the wood and polymer fractions, respectively, based on the TGA curves for the individual components of WPC. TGA curves of the additives, maleic-anhydride-modified polypropylene and lubricant, were assigned to the polymer fraction. The heating rate was fitted to the thermal degradation of the single components by using dynamic and isothermal segments. The results show that the wood flour and polymer fractions can be quantified by TGA. For the final developed method, the deviations from the expected wood flour and polymer fractions were not exceeding 5.4% and 14.3%, respectively. Amounts of wood flour and polymer of WPC with known formulation can be rapidly quantified using TGA, therefore, this method is a useful tool for production control.
Highlights
▸ We developed a special thermogravimetric analysis (TGA) method to quantify the mass percentage of wood flour and polypropylene copolymer in wood plastic composites (WPC). ▸ We fitted the heating rate to the thermal degradation of the single components by using dynamic and isothermal segments. ▸ We showed that WPC with known composition can be rapidly quantified with TGA measurements, therefore, TGA is a useful tool for WPC production control.
