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Effects of Water Soaking–drying Cycles on Thermally Modified Spruce Wood–plastic Composites.

Susanna Källbom, Kristiina Lillqvist, Steven Spoljaric, Jukka Seppälä, Kristoffer Segerholm, Lauri Rautkari, Mark Hughes, Magnus Wålinder

Abstract


The overall aim of this work was to gain more insight on the potential of modified wood (TMW) components for use in wood–thermoplastic composites (WPCs). Laboratory-scale TMWPCs were produced, and the effects of severe water soaking–drying cycles on the samples were studied. Water sorption behavior and resulting dimensional and micromorphological changes were also studied, and the results were compared with those of unmodified wood–plastic composites (UWPCs) used as control. The TMW was prepared by cutting a spruce board into half and subjecting one-half to an atmosphere of superheated steam at atmospheric pressure with a peak temperature of 210°C, with the other unmodified wood (UW) half as a control. The TMW and UW components were then prepared by a Wiley mill and thereafter sifted into smaller (mesh 0.20-0.40 mm) and larger (mesh 0.40-0.63 mm) size fractions. A portion of the wood components were also subjected to thermal extraction (HE). Composite samples with these different wood components, polypropylene (PP) matrix, and maleated PP (MAPP) as coupling agent (50/48/2 wood/PP/MAPP ratio by weight) were then prepared by using a Brabender mixer followed by hot pressing. The matching micromorphology of the composites before and after the soaking–drying cycles was analyzed using a surface preparation technique based on ultraviolet-laser ablation combined with scanning electron microscopy. The results of the water absorption tests showed, as hypothesized, a significantly reduced water absorption and resulting thickness swelling at the end of a soaking cycle for the TMWPCs compared with the controls (UWPCs). The water absorption was reduced with about 50-70% for TMWPC and 60-75% for HE-TMWPC. The thickness swelling for TMWPCs was reduced with about 40-70% compared with the controls. Similarly, the WPCs with HE-UW components absorbed about 20-45% less moisture and showed a reduced thickness swelling of about 25-40% compared with the controls. These observations also were in agreement with the micromorphology analysis of the composites before and after the moisture cycling which showed a more pronounced wood–plastic interfacial cracking (de-bonding) as well as other microstructure changes in the controls compared with those prepared with TMW and HE-UW components. Based on these observations, it is suggested that these potential bio-based building materials show increased potential durability for applications in harsh outdoor environments, in particular TMWPCs with a well-defined and comparably small size fractions of TMW components.

 


Keywords


Thermally modified wood (TMW), wood-plastic composite (WPC), water absorption, dimensional stability, micromorphology, scanning electron microscopy (SEM), UV-laser ablation

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References


Arwinfar F, Hosseinihashemi SK, Latibari AJ, Lashgari A, Ayrilmis N (2016) Mechanical properties and morphology of wood plastic composites produced with thermally modified beech wood. BioResources 11(1):1494-1504.

Askanian H, Verney V, Commereuc S, Guyonnet R,Massardier V (2015) Wood polypropylene composites prepared by thermally modified fibers at two extrusion speeds: Mechanical and viscoelastic properties. Holzforschung 69(3):313-319.

Ayrilmis N, Jarusombuti S, Fueangvivat V, Bauchongkol P (2011) Effect of thermal-treatment of wood fibres on properties of flat-pressed wood plastic composites. Polym Degrad Stabil 96:818-822.

Butylina S, Martikka O, Karki T (2010) Comparison of water absorption and mechanical properties of wood–plastic composites made from polypropylene and polylactic acid. Wood Mater Sci Eng 5(3-4):220-228.

Butylina S, Martikka O, Karki T (2011) Properties of wood fibre-polypropylene composites: Effect of wood fibre source. Appl Compos Mater 18(2):101-111.

Clemons C, Rowell RM, Plackett D, Segerholm BK (2013) Chapter 13. Wood/non wood thermoplastic composites. Pages 473-508 in RM Rowell, ed. Handbook of wood chemistry and wood composites, 2nd edition. CRC Press, Boca Raton, FL.

Esteves BM, Pereira HM (2009) Wood modification by heat treatment: A review. BioResources 4(1):370-404.

Hill CAS (2006) Wood modification: Chemical, thermal and other processes. John Wiley and Sons, Chichester, England.

Hosseinaei O, Wang S, Taylor AM, Kim J-W (2012) Effect of hemicellulose extraction on water absorption and mold susceptibility of wood-plastic composites. Int Biodeterior Biodegrad 71:29-35.

Hosseinihashemi SK, Arwinfar F, Najafi A, Nemli G, Ayrilmis N (2016) Long-term water absorption behavior of thermoplastic composites produced with thermally treated wood. Measurement 86:202-208.

Ibach R, Sun G, Gnatowski M, Glaeser J, Leung M, Haight J (2016) Exterior decay of wood–plastic composite boards: Characterization and magnetic resonance imaging. Forest Prod J 66(1):4-17.

Kuka E, Cirule D, Kajaks J, Andersone I, Andersons B (2016) Wood plastic composites made with thermally modified birch residues. Int Wood Prod J 7(4):225-230.

Lillqvist K, Kallbom S, Altgen M, Belt T, Rautkari L (2019) Water vapour sorption properties of thermally modified and pressurised hot-water-extracted wood powder. Holzforschung 73(12):1059-1068.

Lunawood (2017) www.lunawood.com/composite (26February 2018).

Ozdemir F, Ayrilmis N, Kaymakci A, Kwon JH (2014) Improving dimensional stability of injection molded wood plastic composites using cold and hot-water extraction methods. Maderas Cienc Tecnol 16(3):365-372.

Pelaez-Samaniago MR, Yadama V, Lowell E, Amidon TE, Chaffee TL (2013) Hot water extracted wood fiber for production of wood plastic composites (WPCs). Holzforschung 67(2):193-200.

Segerholm BK, Ibach RE, Westin M (2012a) Moisture sorption, biological durability, and mechanical performance of WPC containing modified wood and polylactates. BioResources 7(4):4575-4585.

Segerholm BK, Rowell RM, Larsson-Brelid P, Walinder MEP, Westin M, Alfredsen G (2007) Improved durability and moisture sorption characteristics of extruded wood-plastic composites made from chemically modified wood. Pages 253-258 in 9th International Conference on Wood and Biofiber Plastic Composites, May 21-23, 2007, Monona Terrace Community and Convention Center, Madison, WI.

Segerholm BK, Vellekoop S,Walinder ME (2012b) Process related mechanical degradation of the wood component in high-wood-content wood-plastic composites. Wood Fiber Sci 44(2):145-154.

Tufan M, Guleç T, Pesman E, Ayrilmis N (2016) Technological and thermal properties of thermoplastic composites filled with heat-treated alder wood. BioResources 11(2):3153-3164.

Walinder M, Omidvar A, Seltman J, Segerholm K (2009) Micromorphological studies of modified wood using a surface preparation technique based on ultraviolet laser ablation. Wood Mater Sci Eng 1-2:46-51.

Westin M, Larsson-Brelid P, Segerholm BK, van den Oever M (2008) Wood plastic composites from modified wood. Part 3. Durability of WPCs with bioderived matrix. In Proc. 39th Annual Meeting of the International Research Group on Wood Preservation (IRG), May 25-29, 2008, IRG/WP 08-40423, Istanbul, Turkey. 17 pp.


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